Notice2023-24238
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Port of Alaska's North Extension Stabilization Step 1 (NES1) Project in Anchorage, Alaska
Primary source
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Published
November 6, 2023
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the Port of Alaska (POA) for authorization to take marine mammals incidental to the NES1 project at the existing port facility in Anchorage, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, 1-year renewal that could be issued under certain circumstances and if all requirements are met, as described in the Request for Public Comments section 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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[Federal Register Volume 88, Number 213 (Monday, November 6, 2023)]
[Notices]
[Pages 76576-76623]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-24238]
[[Page 76575]]
Vol. 88
Monday,
No. 213
November 6, 2023
Part V
Department of Commerce
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National Oceanic and Atmospheric Administration
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Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to the Port of Alaska's North Extension
Stabilization Step 1 (NES1) Project in Anchorage, Alaska; Notice
Federal Register / Vol. 88, No. 213 / Monday, November 6, 2023 /
Notices
[[Page 76576]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XD366]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Port of Alaska's North
Extension Stabilization Step 1 (NES1) Project in Anchorage, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the Port of Alaska (POA) for
authorization to take marine mammals incidental to the NES1 project at
the existing port facility in Anchorage, Alaska. Pursuant to the Marine
Mammal Protection Act (MMPA), NMFS is requesting comments on its
proposal to issue an incidental harassment authorization (IHA) to
incidentally take marine mammals during the specified activities. NMFS
is also requesting comments on a possible one-time, 1-year renewal that
could be issued under certain circumstances and if all requirements are
met, as described in the Request for Public Comments section 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 December
5, 2023.
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#f3baa7a3dd878a809c9ddd9e9c9c8196b39d9c9292dd949c85"><span class="__cf_email__" data-cfemail="8cc5d8dca2f8f5ffe3e2a2e1e3e3fee9cce2e3ededa2ebe3fa">[email protected]</span></a>. 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.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, 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="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> 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.
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 action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
Accordingly, NMFS has prepared an Environmental Assessment (EA) to
consider the environmental impacts associated with the issuance of the
proposed IHA. NMFS' EA is available 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>. 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 request.
Summary of Request
On July 19, 2022, NMFS received a request from the POA for an IHA
to take marine mammals incidental to construction activities related to
the NES1 project in Anchorage, Alaska. Following NMFS' review of the
application, the POA submitted revised versions on December 27, 2022,
July 28, 2023, and August 31, 2023. The application was deemed adequate
and complete on September 7, 2023. The POA submitted a final version
addressing additional minor corrections on September 21, 2023. The
POA's request is for take of seven species of marine mammals by Level B
harassment and, for a subset of these species (i.e., harbor seal (Phoca
vitulina) and harbor porpoise (Phocoena phocoena)), Level A harassment.
Neither the POA nor NMFS expect serious injury or mortality to result
from this activity and, therefore, an IHA is appropriate.
NMFS previously issued IHAs to the POA for similar work (85 FR
19294, April 6, 2020; 86 FR 50057, September 7, 2021). The POA complied
with all the requirements (e.g., mitigation, monitoring, and reporting)
of the previous IHAs, and information regarding their monitoring
results may be found in the Effects of the Specified Activity on Marine
Mammals and their Habitat and Estimated Take section of this notice and
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>.
This proposed IHA would cover 1 year of the ongoing Port of Alaska
Modernization Program (PAMP) for which the POA obtained prior IHAs and
intends to request additional take authorization for subsequent facets
of the program. The PAMP involves construction activities related to
the
[[Page 76577]]
modernization of the POAs marine terminals.
Description of Proposed Activity
Overview
The POA, located on Knik Arm in upper Cook Inlet, provides critical
infrastructure for the citizens of Anchorage and a majority of the
citizens of Alaska. The North Extension at the POA is a failed bulkhead
structure that was constructed between 2005 and 2011. Parts of the
North Extension bulkhead structure and the surrounding upland area are
unstable and collapsing, and some of the sheet piles are visibly
twisted and buckled. The structure presents safety hazards and
logistical impediments to ongoing Port operations, and much of the
upland area is currently unusable. The NES project would result in
removal of the failed sheet pile structure and reconfiguration and
realignment of the shoreline within the North Extension, including the
conversion of approximately 0.05 square kilometers (km\2\; 13 acres) of
developed land back to intertidal and subtidal habitat within Knik Arm.
The NES project would be completed in two distinct steps, NES1 and
NES2, separated by multiple years and separate permitting efforts. This
notice is applicable to a proposed IHA for the incidental take of
marine mammals during in-water construction associated with NES1.
The NES1 project would involve the removal of portions of the
failed sheet pile structure to stabilize the North Extension. The POA
anticipates this project would begin on April 1, 2024 and extend
through November 2024. They estimate that work would occur over
approximately 250 hours on 110 nonconsecutive days. The NES1 project
would remove approximately half of the North Extension structure
extending approximately 274 meters (m) north from the southern end of
the North Extension. This project would also stabilize the remaining
portion of the North Extension by creating an end-state embankment. In-
water construction associated with this project includes vibratory
installation and removal of 81 24-inch (61-centimeter (cm)) or 36-inch
(91-cm) temporary steel pipe stability template piles and vibratory
removal, pile splitting and pile cutting (and possible impact removal)
of approximately 4,216 sheet piles from the structure tailwalls, cell
faces (bulkhead), and closure walls. Sound produced by these
construction activities may result in the take of marine mammals, by
harassment only.
Dates and Duration
The POA anticipates that NES1 in-water construction activities
would begin on April 1, 2024 and extend through November 2024. In-water
pile installation and removal associated with the NES1 project is
anticipated to take place over approximately 246.5 hours on 110
nonconsecutive days between these dates (see table 1 for estimated
production rates and durations). While the exact sequence of demolition
and construction is uncertain, an estimated schedule of sheet pile
removal and temporary stability template pile installation and removal
is shown in Table 2.
Table 1--Pile Installation and Removal Methods and Estimated Durations
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Total
Total Estimated Maximum duration of Average
estimated number of Average vibratory and/ impact removal and production rate, Estimated
Pile type Pile size Structural feature number of piles in or splitter duration strikes per installation piles per day number of
piles the water day in water (range) days
(hours)
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PS 27.5 and PS 31 Sheets........... 19.69 inches (50 cm).. Tailwalls............. 3,536 2,267 2 hours/day........... 150 157 50 (10 to 100) 46
PS 27.5 and PS 31 Sheets........... 19.69 inches (50 cm).. Cell Faces (Bulkhead). 568 568 2 hours/day........... 150 41 30 (10 to 60) 19
PZC26 Sheets....................... 27.88 inches (70 cm).. Closure Walls......... 110 110 2 hours/day........... 150 8 50 (10 to 100) 3
Steel Pipe......................... 24- or 36-inch (61- or Temporary Stability 81 81 15 min/pile........... 0 20.25 4 (2 to 10) 21
91-cm) install. Templates.
Steel Pipe......................... 24- or 36-inch (61- or Temporary Stability 81 81 15 min/pile........... 0 20.25 4 (2 to 10) 21
91-cm) removal. Templates.
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Total.......................... ...................... ...................... ........... ........... ...................... ........... 246.5 ................. 110
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Note: cm = centimeter(s).
Table 2--Estimated Timing and Duration by Month of Pile Installation and Removal Activities
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Activity April May June July August September October November Total
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36-inch (91-cm) or 24-inch (61-cm)
stability template pile
installation:
Piles.......................... 27 14 14 10 10 3 3 0 81
Hours.......................... 6.75 3.50 3.50 2.5 2.5 0.75 0.75 0 20.25
36-inch (91-cm) or 24-inch (61.cm)
stability template pile removal:
Piles.......................... 0 27 13 13 13 10 4 1 81
Hours.......................... 0 6.75 3.25 3.25 3.25 2.5 1 0.25 20.25
Sheet pile vibratory hammer
removal:
Piles.......................... ........... ........... ........... ........... ........... ........... ........... ........... ...........
Hours.......................... 10 45 60 60 13 10 4 2 206
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Total hours................ 16.75 55.25 66.75 65.75 18.75 15.25 5.75 2.25 246.50
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[[Page 76578]]
The POA has presented this schedule using the best available
information derived from what is known of the North Extension Site and
the POA's experience with similar construction and demolition projects.
The POA plans to conduct as much work as possible prior to August
through October, when there is higher Cook Inlet beluga whale (CIBW;
Delphinapterus leucas) abundance. However, as described below, due to
the instability of the North Extension site, it is important that the
POA attempt to complete the NES1 in a single construction season, which
may necessitate work in August through October. Potential consequences
of pausing the construction season (i.e., stopping work from August
through October) include de-rating the structural capacity of existing
POA docks, a shutdown of dock operations due to deteriorated
conditions, or an actual collapse of one or more dock structures. The
potential for collapse increases with schedule delays, due to both
worsening deterioration and the higher probability of a significant
seismic event.
A typical construction season at the POA extends from approximately
mid-April to mid-October (6 months) and may include November. Exact
dates of ice-out in the spring and formation of new ice in the fall
vary from year to year and cannot be predicted with accuracy. In-water
pile installation and removal cannot occur during the winter months
when ice is present because of the hazards associated with moving ice
floes that change directions four times a day, preventing the use of
tugs, barges, workboats, and other vessels. Ice movement also prevents
accurate placement of piles.
Due to the design of the existing sheet pile wall, demolition must
occur in a sequential and uninterrupted manner to prevent structural
failure of the wall as demolition progresses. This safety requirement
limits the POA's ability to re-sequence in-water sheet pile extraction
and temporary pile installation, as the already compromised bulkhead
structure may become further destabilized. The POA therefore plans to
complete all work between April and November 2024, and requests an IHA
for the NES1 project for 1 year that is effective as of April 1, 2024.
All pile-driving would occur during daylight hours.
Specific Geographic Region
The Municipality of Anchorage is located in the lower reaches of
Knik Arm of upper Cook Inlet (see Figure 2-1 in the POA's application).
The POA sits on the industrial waterfront of Anchorage, just south of
Cairn Point and north of Ship Creek (lat. 61[deg]15' N, long.
149[deg]52' W; Seward Meridian). Knik Arm and Turnagain Arm are the two
branches of upper Cook Inlet, and Anchorage is located where the two
arms join.
Cook Inlet is a large tidal estuary that exchanges waters at its
mouth with the Gulf of Alaska. The inlet is roughly 20,000 km\2\ in
area, with approximately 1,350 linear kilometer (km) of coastline (Rugh
et al., 2000) and an average depth of approximately 100 m. Cook Inlet
is generally divided into upper and lower regions by the East and West
Forelands. Freshwater input to Cook Inlet comes from snowmelt and
rivers, many of which are glacially fed and carry high sediment loads.
Currents throughout Cook Inlet are strong and tidally periodic, with
average velocities ranging from 3 to 6 knots (Sharma and Burrell,
1970). Extensive tidal mudflats occur throughout Cook Inlet, especially
in the upper reaches, and are exposed at low tides.
Cook Inlet is a seismically active region susceptible to
earthquakes and has some of the highest tides in North America (NOAA,
2015) that drive surface circulation. Cook Inlet contains substantial
quantities of mineral resources, including coal, oil, and natural gas.
During winter, sea, beach, and river ice are dominant physical forces
within Cook Inlet. In upper Cook Inlet, sea ice generally forms in
October to November, and continues to develop through February or March
(Moore et al., 2000).
Northern Cook Inlet bifurcates into Knik Arm to the north and
Turnagain Arm to the east. Knik Arm is generally considered to begin at
Point Woronzof, 7.4 km southwest of the POA. From Point Woronzof, Knik
Arm extends about 48 km in a north-northeasterly direction to the
mouths of the Matanuska and Knik rivers. At Cairn Point, just northeast
of the POA, Knik Arm narrows to about 2.4 km before widening to as much
as 8 km at the tidal flats northwest of Eagle Bay at the mouth of Eagle
River.
Knik Arm comprises narrow channels flanked by large tidal flats
composed of sand, mud, or gravel, depending upon location.
Approximately 60 percent of Knik Arm is exposed at Mean Lower Low Water
(MLLW). The intertidal (tidally influenced) areas of Knik Arm are
mudflats, both vegetated and unvegetated, which consist primarily of
fine, silt-sized glacial flour. Freshwater sources often are glacially
born waters, which carry high suspended sediment loads, as well as a
variety of metals such as zinc, barium, mercury, and cadmium. Surface
waters in Cook Inlet typically carry high silt and sediment loads,
particularly during summer, making Knik Arm an extremely silty, turbid
waterbody with low visibility through the water column. The Matanuska
and Knik Rivers contribute the majority of fresh water and suspended
sediment into Knik Arm during summer. Smaller rivers and creeks also
enter along the sides of Knik Arm (U.S. Department of Transportation
and Port of Anchorage, 2008).
Tides in Cook Inlet are semidiurnal, with two unequal high and low
tides per tidal day (tidal day = 24 hours, 50 minutes). Due to Knik
Arm's predominantly shallow depths and narrow widths, tides near
Anchorage are greater than those in the main body of Cook Inlet. The
tides at the POA have a mean range of about 8 m, and the maximum water
level has been measured at more than 12.5 m at the Anchorage station
(NMFS, 2015). Maximum current speeds in Knik Arm, observed during
spring ebb tide, exceed 7 knots. These tides result in strong currents
in alternating directions through Knik Arm and a well-mixed water
column. The navigation harbor at the POA is a dredged basin in the
natural tidal flat. Sediment loads in upper Cook Inlet can be high;
spring thaws occur, and accompanying river discharges introduce
considerable amounts of sediment into the system (Ebersole and Raad,
2004). Natural sedimentation processes act to continuously infill the
dredged basin each spring and summer.
The POA's boundaries currently occupy an area of approximately 0.52
km\2\. Other commercial and industrial activities related to secured
maritime operations are located near the POA on Alaska Railroad
Corporation property immediately south of the POA, on approximately
0.45 km\2\ at a similar elevation. The POA is located north of Ship
Creek, an area that experiences concentrated marine mammal activity
during seasonal runs of several salmon species. Ship Creek serves as an
important recreational fishing resource and is stocked twice each
summer. Ship Creek flows into Knik Arm through the Municipality of
Anchorage industrial area. Joint Base Elmendorf-Richardson (JBER) is
located east of the POA, approximately 30.5 m higher in elevation. The
U.S. Army Defense Fuel Support Point-Anchorage site is located east of
the POA, south of JBER, and north of Alaska Railroad Corporation
property. The perpendicular distance to the west bank directly across
Knik Arm from the POA is approximately 4.2 km. The distance from the
POA (east side)
[[Page 76579]]
to nearby Port MacKenzie (west side) is approximately 4.9 km.
Detailed Description of the Specified Activity
The POA, located on Knik Arm in upper Cook Inlet (Figure 1),
provides critical infrastructure for the citizens of Anchorage and a
majority of the citizens of Alaska. Marine-side infrastructure and
facilities at the POA were constructed largely in the 1960s and are in
need of replacement because they are substantially past their design
life and in poor and deteriorating structural condition. Those
facilities include three general cargo terminals, two petroleum
terminals, a dry barge landing, and an upland sheet-pile-supported
storage and work area. To address deficiencies, the POA is modernizing
its marine terminals through the PAMP to enable safe, reliable, and
cost-effective Port operations. The PAMP will support infrastructure
resilience in the event of a catastrophic natural disaster over a 75-
year design life.
[[Page 76580]]
[GRAPHIC] [TIFF OMITTED] TN06NO23.054
The PAMP is critical to maintaining food and fuel security for the
state. At the completion of the PAMP, the POA will have modern, safe,
resilient, and efficient facilities through which more than 90 percent
of Alaskans will continue to obtain food, supplies, tools, vehicles,
and fuel. The PAMP is divided into five separate phases; these phases
are designed to include projects that have independent utility yet
streamline agency permitting. The projects associated with the PAMP
include:
<bullet> Phase 1: Petroleum and Cement Terminal (PCT Phase 1 and 2)
and South Floating Dock (SFD) replacement;
<bullet> Phase 2A: NES1;
<bullet> Phase 2B: General Cargo Terminals Replacement
(construction planned to begin in 2025);
<bullet> Phase 3: Petroleum, Oil and Lubricants Terminal 2
Replacement;
<bullet> Phase 4: NES2; and
<bullet> Phase 5: Demolition of Terminal 3.
[[Page 76581]]
Phase 1 of the PAMP was completed in 2022. IHAs were issued by NMFS
for both the PCT (Phase 1 and Phase 2; 85 FR 19294, April 6, 2020) and
SFD projects associated with this Phase (86 FR 50057, September 7,
2021). The NES Project would be completed in two distinct steps, NES1
and NES2, separated by multiple years and separate permitting efforts.
The project discussed herein, NES1, is Phase 2A of the PAMP. Ground
improvements work in preparation for NES1 began in 2023, and on-shore
and in-water work for NES1 is planned to commence in April 2024.
The North Extension (the area north of the existing general cargo
docks) was constructed in 2005-2011 under the Port Intermodal Expansion
Project (PIEP), the predecessor effort to the PAMP. The POA considers
the North Extension a failed structure. Parts of the North Extension
bulkhead structure and the surrounding upland area are unstable and
collapsing, and some of the sheet piles are visibly twisted and
buckled. The structure presents safety hazards and logistical
impediments to ongoing Port operations, and much of the upland area is
currently unusable. The currently proposed NES Project overall would
result in removal of the failed sheet pile structure and
reconfiguration and realignment of the shoreline within the North
Extension. NES1 would include the conversion of approximately 0.05
km\2\ (13 acres) of developed land back to intertidal and subtidal
habitat within Knik Arm. While the majority of the Project will be
demolition work, the term ``construction'' as used herein refers to
both construction and demolition work.
The purpose of the NES Project is to stabilize the previously
failed North Extension bulkhead structure and create a new shoreline
that is structurally and seismically stable and balances the
preservation of uplands created in the past while addressing the
formation of unwanted sedimentation within the U.S. Army Corps of
Engineers (USACE) Anchorage Harbor. The NES Project will also improve
safety for maneuvering vessels at the northern berths. Previous
establishment of the North Extension changed the hydrodynamics of the
area and resulted in more rapid accumulation of sediments at the
existing cargo dock faces, as well as a smaller turning area for
vessels. The Municipality of Anchorage and the POA have identified the
NES Project as a priority for the PAMP, due to the impact of the
existing structure's geometry upon the USACE Anchorage Harbor Project,
mariners' concerns regarding impacts to safe ship-berthing operations,
and engineering concerns regarding structural and geotechnical
stability of the system. The existing structure poses significant risk
for continued deterioration and could result in significant release of
impounded fill material into the Port's vessel operating and mooring
areas, and into the USACE Anchorage Harbor Project. Accordingly, a
significant portion of the NES work has been designated for inclusion
in NES1 as Phase 2A PAMP efforts, specifically those portions of the
existing structure that are closest to the north end of the existing
cargo terminals. Creation of a safe and stable uplands area will
support POA operations while also addressing concerns of adverse
impacts upon the Federal Navigation Channel and Dredging Program.
Existing North Extension Structure
The existing North Extension bulkhead structure is an OPEN CELL
SHEET PILE (OCSP) design. Demolition of the existing OCSP structure
will include removal and disposal of the southerly OCSP bulkhead walls
and associated backlands. The OCSP bulkhead is a retaining structure
filled with soil that is composed of 29 interconnected open cells, each
approximately 8 m wide, with 30 tailwalls that are up to 61 m long (see
Figure 1-3 in the POA's application). Each cell is about 20 sheets wide
across the face, which is along the water. Each tailwall consists of
approximately 118 sheet piles that extend landward into the filled
area, orthogonal to the sheet piles along the face (table 1). The sheet
piles interlock through a series of thumb-finger joints or interlocks
(where two sheet piles are connected along their length; see Figure 1-5
in the POA's application) along the cell faces and tailwalls. Wye
joints occur where three sheet piles are connected at the interface
between two neighboring sheet pile cell faces and the adjoining
tailwall (see Figure 1-6 in the POA's application). Two z-pile closure
walls close the gaps between structures, one on each end of the
bulkhead (see Figure 1-4 in the POA's application). The total number of
sheet piles in the existing structure that would be removed is
approximately 4,216, although the exact number of sheet piles in the
existing structure is not known with certainty.
Demolition of the failed sheet pile structure would be accomplished
through excavation and dredging of impounded soils (fill material), and
cutting and removal of the existing sheet piles, most likely through
use of a splitter and vibratory hammer. Demolition of the OCSP cell
components would not commence until ground improvements necessary to
protect the horizontal to vertical ratio (H:V) of 2H:1V embankment
slope have been completed. Ground improvements were scheduled for 2023
and are underway. The sequencing of in-water events, including how
construction would proceed while maintaining stability among the
structure's cells, is unknown. It is anticipated that the actual
methods, including types of equipment and numbers of hours and days of
each activity, would be determined based on the engineering
specifications for the NES1 project as determined by the Construction
Contractor and the Design Build Team designer of record (DOR). The NES1
DOR and Construction Contractor have been selected by the POA, but
their Construction Work Plan has not yet been completed and some actual
construction techniques are likely to be refined adaptively as
construction advances due to the stability risk of the existing
impounded materials. The following project description is based on the
best available information at this time considering the POA's knowledge
of the condition of the North Extension and their experience with
similar marine construction and demolition projects, which NMFS has
determined sufficient for the purposes of the IHA application.
NES1 Project Activities
The NES1 Project would result in a reconfiguration and realignment
of the shoreline through removal of portions of the failed sheet pile
structure to stabilize the North Extension. Before NES1 commences, the
upland area would be prepared with ground improvements to stabilize the
existing fill. Ground improvements will take place in the dry, landward
of the existing failed sheet pile structure and underneath the area
where filter rock and armor rock would later be placed to stabilize the
new shoreline. Ground improvement work began in 2023.
Construction of NES1 will include completion of the following
tasks:
<bullet> Dredging and offshore disposal of approximately 1.35
million cubic yards (CY) of material down to -12 m MLLW;
<bullet> Excavation of 115,000 CY of material;
<bullet> Demolition and removal of the failed existing sheet pile
structure; and
<bullet> Shoreline stabilization including placement of granular
fill, filter rock, and armor rock along the new face of the shoreline.
NES1 would remove approximately half of the North Extension
structure extending approximately 274 m north
[[Page 76582]]
from the southern end of the North Extension. NES1 would also stabilize
the remaining portion of the North Extension by creating an end-state
embankment with a top elevation of +12 m MLLW, sloping to a toe
elevation of approximately -12 m MLLW. The lower portion of the
embankment slope from -12 m MLLW to approximately 0 m MLLW would be
constructed with a 6H:1V slope and would be unarmored. A grade-break
would occur above these elevations as the slope will transition to a
2H:1V slope armored rock revetment.
At the cell faces, the depth of the face wall sections varies, with
most extending from a tip elevation of approximately -60 MLLW to a
cutoff elevation of approximately +9 m MLLW (27 m long). The mudline at
the face sheets varies but is thought to be at approximately -11 m
MLLW. This translates into a requirement to demolish sheet piles
approximately 25 m high from the -14-m MLLW elevation to the top of the
containment.
Demolition of the failed sheet pile structure would be accomplished
through excavation and dredging of impounded soils (fill material), and
cutting and removal of the existing sheet piles. Approximately
1,465,000 CY of material would be removed. The material removed from
excavation (115,000 CY) would be stockpiled in the North Extension area
for future use, while the dredged material (1,350,000 CY) would be
disposed of offshore into the Anchorage Harbor Open Water Disposal
Site, which is the authorized USACE offshore disposal area used by the
POA under USACE permit POA-2003-00503-M20.
The NES1 Project in-water work would begin with landside excavation
and in-water dredging along the south shoreline and south half of the
failed sheet pile structure. Any methodology considered for cutting and
removing the steel sheet piles would account for worker safety,
constructability, and minimization of potential acoustic impacts that
the operation may have on marine mammals. The first attempt would be to
extract the sheet piles with direct vertical pulling or with a
vibratory hammer; however, there may be complications with the sheet
pile interlocks, which could become seized, and other means of pile
removal may be required (i.e. shearing or torching). Demolition
activities would begin with the south half of the existing structure,
followed by the north half of NES1 (see Figure 1-8 in the POA's
application). The majority of the demolition work would occur from the
water side to eliminate safety hazards from unexpected movements of
fill material or the sheet piles themselves. The demolition plan also
includes stabilization of the face sheets through installation of
temporary piles and dredging back into the cell to relieve pressure on
the sheet piles and to eliminate any release of material into Cook
Inlet beyond natural tidal forces.
Safety is a top priority regarding planning and executing the work.
There are several risks at the project site to consider when planning
demolition activities, such as strong currents and large tidal swings.
Existing sheet piles and their interlocks are in poor condition. Many
of the sheets may be damaged and bound up, making removal difficult.
There are stability concerns with the failed OCSP structure, where the
POA would have to closely manage allowable fill differentials between
adjacent cells and loading on the face sheets. In-water NES1 activities
and quantities are summarized in Table 3 (NES1 activities to be
completed on land are summarized in table 1-2 in the POA's
application).
Table 3--Summary of In-Water NES1 Project Stages, Activities, and
Approximate Quantities
------------------------------------------------------------------------
Total anticipated
Type of activity Size and type amount or number
------------------------------------------------------------------------
Dredging of fill material....... Granular fill..... 1,350,000 CY.
At-sea transit and disposal of Granular fill..... 1,350,000 CY.
dredged fill.
Cutting piles with sheet 19.69-inch (50 cm) Unknown.\1\
splitter (vertical). sheet piles, cut
into vertical.
Cutting piles with shears or 19.69-inch (50 cm) Unknown.\1\
torch (horizontal) \2\. sheet piles.
Vibratory or direct pull removal 19.69-inch (50 cm) 4,216 sheet piles.
of sheet piles \3\. sheet piles,
removed in
vertical panels.
Installation and removal of 81 24- or 36-inch 81 installations,
temporary steel pipe piles. (61- or 91-cm) 81 removals.
piles.
Slope construction.............. Bedding, filter 60,500 CY.
rock, armor stone.
------------------------------------------------------------------------
\1\ The total number of sheet piles to be cut would be a subset of the
estimated 4,216 sheet piles needed to be removed.
\2\ Deploying divers or underwater shear equipment would be the last
resort for removing sheet piles.
\3\ Most of the waterside face and tailwall sheets would be cut in the
dry to improve operational safety.
Dredging and Disposal
Dredging would be performed with a derrick barge using a clamshell
bucket, and would likely take place for 24 hours per day for the
duration of the project. One barge would perform the dredging
associated with the sheet pile removal, working concurrently and in
support of the crane barge removing the sheets. Another barge would
perform dredging in the remaining proposed project area. This barge
would start with removing the existing armor rock on the south slope
and work its way north behind the OSCP bulkhead. Dredged material would
be placed on a dump barge and taken by tug boat for disposal at the
Anchorage Harbor Open Water Disposal Site.
Dredging for NES1 will take place in an area that has been part of
a working port for more than 50 years, where dredging activities are
common. Take of marine mammals by dredging is not anticipated or
proposed to be authorized due to the low intensity and stationary
nature of the sounds produced by dredging and its perennial presence
over many years in the same general location near the project site.
Further, the sounds produced by dredging are not meaningfully different
and are unlikely to exceed sounds produced by ongoing normal industrial
activities at the port. Lastly, mitigation measures described in the
Proposed Mitigation section would ensure that direct physical
interaction with marine mammals during dredging activities would be
avoided. Therefore, dredging will not be considered further in this
notice.
Excavation
Landside excavation would occur with loaders and excavators to
remove the top portion of fill material and open up work for initial
sheet pile cutting and removal. This excavation would begin to relieve
pressure along the sheet wall face and expose the tops of the sheet
piles to mitigate the risk of damaging sheets while dredging with a
clamshell
[[Page 76583]]
bucket. The sheet piles could be more easily extracted if undamaged.
The removal elevation would remain above +5 m MLLW in order for the
land equipment to reach the excavation depth with the groundwater and
tidal elevations and ensure that the removed material would be in good
condition. The material removed would be stockpiled at the POA for
future use. Excavation would occur out of water. Therefore, take of
marine mammals related to excavation activities is not anticipated or
proposed to be authorized, and it will not be considered further in
this notice.
Pile Installation and Removal
The sheet pile removal process would begin with the installation of
stability templates (steel pipe piles) along the face of the sheet pile
structure, following excavation and initial dredging work. Once
landside excavation has removed the top portion of fill along the face
of the wall, the POA would follow behind and begin dredging the
material within the cells while maintaining the allowable fill
differential between adjacent cells to maintain structural integrity.
Before dredging deeper than the allowable elevation determined by the
engineer, a crane barge would install temporary stability templates
along the face of the sheet pile structure. The addition of about 27
temporary stability templates would support about one-third of the
bulkhead sheet pile wall during removal of the impounded material.
These templates would reinforce the sheets as material is dredged and
hold them upright to prohibit any sheet deformation and improve the
efficiency and effectiveness of removal. The templates would also
minimize the need to perform horizontal cuts at multiple elevations,
including underwater. With strong currents and low visibility,
performing horizontal cuts underwater poses significant challenges.
After that area has been demolished, the temporary stability template
piles would be removed and re-installed along the next third of the
bulkhead. It is anticipated that three sets of 27 temporary piles would
be required for a total of 81 installations and 81 removals (table 1).
The POA anticipates that the temporary stability template piles would
be 24-inch (61-cm) steel pipe piles. However, it is possible that 36-
inch (91-cm) steel pipe piles would be used instead. Temporary piles
would be installed and removed with a vibratory hammer.
The POA would begin on the southern end of the sheet pile structure
and work their way north along the sheet wall face, installing
templates and dredging fill material while managing fill elevations
from cell to cell (see Figure 1-10 in the POA's application for an
example section for the proposed demolition work). Fill material would
slide down into the dredge area and would continue to be removed until
a cell has been dredged down to -12 m MLLW adjacent to the face sheets
and all pressure of the fill material on the face has been relieved. At
this point in time, the crane barge would begin removing the sheet
piles, starting with the face sheets.
Some sheet piles from the tailwalls would be removed in the dry,
potentially during excavation, depending on construction sequencing and
tide heights. To minimize potential impacts on marine mammals from in-
water sheet pile removal with a vibratory hammer, removal in the dry
would be maximized as feasible; however, until the Construction
Contractor and DOR are under contract, the exact number of sheet piles
that may be removed in the dry is unknown. It is estimated that
approximately 20-30 percent of sheet piles would be removed in the dry.
Additionally, it is possible that some sheet piles may be removed
by direct pulling. Removal of sheet piles by direct pulling where and
when possible would also be maximized as feasible. Once fill material
and impounded soils have been excavated or dredged from both sides of
the sheet piles, it may be adequate to dislodge the sheet piles out of
interlock by lifting or direct pulling.
Although some sheet piles and sheet pile sections would be removed
by direct pulling and/or in the dry, it is anticipated that some sheet
piles and sheet pile sections would need to be removed with a vibratory
hammer in water. Sheet piles may not be extracted easily if soil
adheres to the sheet piles along the embedded length. It is also
possible that competent portions of the interlocks would resist
movement, or that interlocks that are bent or damaged by shearing would
be difficult to separate and require shaking with a vibratory hammer.
During vibratory removal, a vibratory hammer would be suspended
from a crane and connected to a powerpack. The extractor jaw would be
hydraulically locked onto the web of the sheet pile. The pile would be
vibrated as upward vertical force is applied to extract the pile.
Ideally, the piles would slide within the interlock, separating from
the adjacent piles. This may not always be the case, as the pile may
bind, and multiple piles may be dislodged from the original installed
position. Another potential outcome of a pile that binds up is that the
pile web (the thin, flat part between the interlocks) may be
compromised from corrosion or other damage, resulting in the web steel
tearing and partially ripping the pile, necessitating the application
of vertical force to a neighboring pile.
Vertical cuts to split the sheet piles into panels may be made with
a sheet splitter if the interlocks do not release (see Figure 1-10 in
the POA's application). The specific tools that would be used for pile
splitting are not known, but it is anticipated that a splitter would be
used. A pile splitter is a stiffened steel H-beam with some of the
webbing removed. The edges of the H-beam webbing are hardened and form
a large wedge between the flanges. The wedge is set on top of the sheet
pile webbing where a cut is required. The splitter is then driven with
a hammer down the webbing of the sheet pile until the tip of the H-beam
passes the tip of the sheets, cutting the sheet pile all the way
through and separating it into two parts. Multiple cuts split the sheet
pile wall into tall vertical panels that can be removed in smaller
pieces. Cuts in the sheet piles may be spaced 4 to 6 sheets apart and
multiple sheets or pieces would be removed together. Splitters can be
used in the air, water, or in soils and can be driven with impact or
vibratory hammers. The splitter would be used in conjunction with a
vibratory hammer and the POA assumed splitting would produce the same
or similar sound levels to a vibratory hammer used without the splitter
attachment. Therefore, the POA combined use of a vibratory hammer to
remove sheet piles and use of a splitter into a single category (i.e.,
vibratory hammer removal) and treated them the same for time (i.e.,
table 1) and take estimation (see the Estimated Take section).
The POA estimates that an average of approximately 5 minutes of
vibratory hammer application would be required to remove sheet pile
sections. It is unknown how many sheet piles may be included in a
section; the POA anticipates that this number will vary widely. If
sheet piles remain seized in the sediments and cannot be loosened or
broken free with a vibratory hammer, they may be dislodged with an
impact hammer. Use of an impact hammer to dislodge is expected to be
uncommon, with up to 150 strikes (an estimated 50 strikes per pile for
up to three piles) on any individual day or approximately 5 percent of
active hammer duration for each sheet pile. The POA would not use two
vibratory hammers with or without splitters simultaneously.
[[Page 76584]]
Alternative means of pile removal include dredging or excavation to
reduce further pile embedment, and cutting sheet piles using hydraulic
shears or underwater ultrathermic cutting. When feasible, sheet piles
would be removed in one piece, without cutting. Similarly, use of
cutting methods to cut piles into sections that could be more easily
removed would take place out of water when feasible. The POA
anticipates that hydraulic shears may be used to cut sheet piles both
in and out of water. The POA anticipates that sounds produced by
hydraulic shears would be brief, low level, and intermittent, imparting
minimal sound energy into the water column. A single closure of the
shears on sheet pile is anticipated to successfully sever one or
multiple sheets depending on the model and jaw depth. The POA
anticipates that a single cut may require up to 2 minutes for the
shears to close, although the duration of a single cut is likely to be
less than 2 minutes. Therefore, take of marine mammals associated with
hydraulic shearing is not anticipated or proposed to be authorized.
Underwater ultrathermic cutting is performed by commercial divers
using hand-held equipment to cut or melt through ferrous and non-
ferrous metals, and could be used to cut the zinc-coated OCSP
structure. These systems operate through a torch-like process,
initiated by applying a melting amperage to a steel tube packed with
alloy steel rods, sometimes mixed with aluminum rods to increase the
heat output. In the hands of skilled commercial divers, underwater
ultrathermic cutting is reputed to be relatively fast and efficient,
cutting through approximately 2 to 4 inches (5 to 10 cm) per minute,
depending upon the number of divers deployed. This efficacy may be
constrained by the requirement to secure the severed piles from falling
into the inlet to prevent an extreme hazard to the diver cutting the
piles. Tidally driven currents in Cook Inlet may limit dive times to
approximately 2 to 3 hours per high- and low-tide event, depending upon
the tide cycle and the ability of divers to efficiently perform the
cutting task while holding position during high current periods. Take
of marine mammals associated with underwater ultrathermic cutting is
not anticipated or proposed to be authorized as this activity is not
considered to produce sound.
Once the face sheets have been removed, the crane barge would
remove the stability templates for use on other cells. At this point,
the tailwalls would become independent walls with only fill material
between them. The crane barge would work to extract as many tailwall
sheets as possible until additional relief dredging is required to
allow for vibratory removal. At this point, the crane barge would
continue ahead to the north while the dredge rig falls back to continue
dredging between the sheets. The POA would continue to remove the face
wall and tailwall sheets from south to north until the OCSP structure
has been removed.
A key consideration of the NES1 project is to avoid rapid release
of the impounded soils into the inlet. This is an important safety
issue presenting a risk to construction personnel working in or near
the cells in the immediate area of such an event. It is also an
important operational issue to the POA, as releasing large quantities
of materials into the inlet could quickly foul the adjoining cargo
terminal berths (see Figure 1-7 in the POA's application). To avoid
rapid release of the impounded soils, the demolition would need to be
managed to account for the soil pressure of the adjacent adjoining
cells. Failure to properly manage this process would likely result in
the earth pressure generated by adjacent adjoining cells exerting
lateral forces that would cause catastrophic tailwall failures. Also,
the sheets joined in interlock are susceptible to bending in the weak
axis, which could result in rotational forces that may overcome the
vertical interlocks, causing the interlocks to unzip, again resulting
in catastrophic tailwall failures and or face wall failures. Qualified
professional engineers on the Design Build Team would develop the
Construction Work Plan with the technical details to ameliorate these
risks.
The sheet pile interlocks would not prevent the flow of seawater
into soils impounded within the OCSP cells. The water infiltration
would be most prevalent at the face sheets; however, dynamic wave
forces, the variable sea level height of the inlet, and variations in
the impounded soils and associated permeability would make the
interface elevation between unsaturated and saturated soils dynamic.
Because saturated soils cannot resist shear, land-based excavation
could be safely accomplished at a height above the saturated soil depth
to be determined by the DOR, lest the equipment weight exceed the soil-
bearing capacity.
Shoreline Stabilization
After the existing sheet pile structure has been removed, the
sloped shoreline would be secured with armor stone placed on a layer of
filter rock and granular fill. Placement of armor rock requires good
visibility of the shore as each rock would be placed carefully to
interlock with surrounding armor rock. The POA therefore anticipates
that placement of armor rock would occur in the dry at low tide levels
when feasible; however, some placement of armor rock, filter rock, and
granular fill would occur in water. No impacts on marine mammals from
placement of armor rock, filter rock, and granular fill in the dry are
anticipated and therefore this activity will not be discussed further.
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
There are seven species of marine mammals that may be found in
upper Cook Inlet during the proposed construction and demolition
activities. Sections 3 and 4 of the IHA 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, instead of reprinting the
information. Additional information regarding population trends and
threats may be found in NMFS' Stock Assessment Reports (SARs; <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>) 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>).
Additional information on CIBWs may be found in NMFS' 2016 Recovery
Plan for the CIBW, available online at <a href="https://www.fisheries.noaa.gov/resource/document/recovery-plan-cook-inlet-beluga-whale-delphinapterus-leucas">https://www.fisheries.noaa.gov/resource/document/recovery-plan-cook-inlet-beluga-whale-delphinapterus-leucas</a>, and NMFS' 2023 report on the abundance and trend of CIBWs in
Cook Inlet in June 2021 and June 2022, available online at <a href="https://www.fisheries.noaa.gov/resource/document/abundance-and-trend-belugas-delphinapterus-leucas-cook-inlet-alaska-june-2021-and">https://www.fisheries.noaa.gov/resource/document/abundance-and-trend-belugas-delphinapterus-leucas-cook-inlet-alaska-june-2021-and</a>.
Table 4 lists all species or stocks for which take is expected and
proposed to be authorized for this activity, and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. PBR is defined by the MMPA as the maximum
number of
[[Page 76585]]
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 proposed to be authorized
here, PBR and annual serious injury and mortality from anthropogenic
sources are included here as gross indicators of the status of the
species or stocks 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. Alaska and Pacific SARs (e.g., Carretta, et al., 2023; Young
et al., 2023). Values presented in Table 4 are the most recent
available at the time of publication and are available 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>. The most recent abundance estimate for
CIBWs, however, is available from Goetz et al. (2023) and available
online at <a href="https://www.fisheries.noaa.gov/feature-story/new-abundance-estimate-endangered-cook-inlet-beluga-whales">https://www.fisheries.noaa.gov/feature-story/new-abundance-estimate-endangered-cook-inlet-beluga-whales</a>.
Table 4--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/MMPA status; Stock abundance Nbest,
Common name Scientific name MMPA stock strategic (Y/N) (CV, Nmin, most recent PBR Annual M/
\1\ abundance survey) \2\ SI \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray whale...................... Eschrichtius robustus.. Eastern N Pacific...... -/-; N 26,960 (0.05, 25,849, 801 131
2016).
Family Balaenopteridae (rorquals):
Humpback whale.................. Megaptera novaeangliae. Hawaii................. -, -, N 11,278 (0.56, 7,265, 127 27.09
2020).
Mexico-North Pacific... T, D, Y N/A (N/A, N/A, 2006).. \6\ UND 0.57
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Beluga whale.................... Delphinapterus leucas.. Cook Inlet............. E/D; Y \5\ 331 (0.076, 290, 0.53 0
2022).
Killer whale.................... Orcinus orca........... Eastern North Pacific -/-; N 1,920 (N/A, 1,920, 19 1.3
Alaska Resident. 2019).
Eastern North Pacific -/-; N 587 (N/A, 587, 2012).. 5.9 0.8
Gulf of Alaska,
Aleutian Islands and
Bering Sea Transient.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
Harbor porpoise................. Phocoena phocoena...... Gulf of Alaska......... -/-; Y 31,046 (0.214, N/A, \6\ UND 72
1998).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller sea lion................ Eumetopias jubatus..... Western................ E/D; Y 52,932 (N/A, 52,932 318 255
2019).
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... Cook Inlet/Shelikof -/-; N 28,411 (N/A, 26,907, 807 107
Strait. 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.
\4\ UNK means unknown.
\5\ This abundance estimate is from Goetz et al. (2023).
\6\ UND means undetermined.
On June 15, 2023, NMFS released an updated abundance estimate for
endangered CIBWs in Alaska (Goetz et al., 2023) that incorporates
aerial survey data from June 2021 and 2022, but which is not included
in the most recent SAR (Young et al., 2023). Data collected during NMFS
recent aerial survey effort suggest that the whale population is stable
or may be increasing slightly. Goetz et al. (2023) estimated that the
population size is currently between 290 and 386, with a median best
estimate of 331. In accordance with the MMPA, this population estimate
will be incorporated into the next draft CIBW SAR, which will be
reviewed by an independent panel of experts, the Alaska Scientific
Review Group. After this review, the SAR will be made available as a
draft for public review before being finalized. We have determined that
it is appropriate to consider the CIBW estimate of abundance reported
by Goetz et al. (2023) in our analysis rather than the older estimate
currently available from
[[Page 76586]]
the Alaska SAR (Young et al., 2023) because it is based on the most
recent and best available science.
As indicated above, all seven species (with nine managed stocks) in
Table 4 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur. Minke whales
(Balaenoptera acutorostrata) and Dall's porpoises (Phocoenoides dalli)
also occur in Cook Inlet; however, the spatial occurrence of these
species is such that take is not expected to occur, and they are not
discussed further beyond the explanation provided here. Data from the
Alaska Marine Mammal Stranding Network database (NMFS, unpublished
data) provide additional support for these determinations. From 2011 to
2020, only one minke whale and one Dall's porpoise were documented as
stranded in the portion of Cook Inlet north of Point Possession. Both
were dead upon discovery; it is unknown if they were alive upon their
entry into upper Cook Inlet or drifted into the area with the tides.
With very few exceptions, minke whales and Dall's porpoises do not
occur in upper Cook Inlet, and therefore take of these species is
considered unlikely.
In addition, sea otters (Enhydra lutris) may be found in Cook
Inlet. However, sea otters are managed by the U.S. Fish and Wildlife
Service (USFWS) and are not considered further in this document.
Gray Whale
The stock structure for gray whales in the Pacific has been studied
for a number of years and remains uncertain as of the most recent
(2022) Pacific SARs (Carretta et al., 2023). Gray whale population
structure is not determined by simple geography and may be in flux due
to evolving migratory dynamics (Carretta et al., 2023). Currently, the
SARs delineate a western North Pacific (WNP) gray whale stock and an
eastern North Pacific (ENP) stock based on genetic differentiation
(Carretta et al., 2023). WNP gray whales are not known to feed in or
travel to upper Cook Inlet (Conant and Lohe, 2023; Weller et al.,
2023). Therefore, we assume that gray whales near the project area are
members of the ENP stock.
An Unusual Mortality Event (UME) along the West Coast and in Alaska
was declared for gray whales in January 2019 (NMFS, 2022a). Since 2019,
143 gray whales have stranded off the coast of Alaska. Preliminary
findings for several of the whales indicate evidence of emaciation, but
the UME is still under investigation, and the cause of the mortalities
remains unknown (NMFS, 2022a; see <a href="https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and">https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2023-gray-whale-unusual-mortality-event-along-west-coast-and</a> for more information).
Gray whales are infrequent visitors to Cook Inlet, but can be
seasonally present during spring and fall in the lower inlet (Bureau of
Ocean Energy Management (BOEM), 2021). Migrating gray whales pass
through the lower inlet during their spring and fall migrations to and
from their primary summer feeding areas in the Bering, Chukchi, and
Beaufort seas (Swartz, 2018; Silber et al., 2021; BOEM, 2021).
Gray whales are rarely documented in upper Cook Inlet and in the
project area. Gray whales were not documented during POA construction
or scientific monitoring from 2005 to 2011 or during 2016 (Prevel-Ramos
et al., 2006; Markowitz and McGuire, 2007; Cornick and Saxon-Kendall,
2008, 2009; Cornick et al., 2010, 2011; Integrated Concepts and
Research Corporation (ICRC), 2009, 2010, 2011, 2012; Cornick and
Pinney, 2011; Cornick and Seagars, 2016); however, one gray whale was
observed near Port MacKenzie during 2020 PCT construction (61 North
(61N) Environmental, 2021) and a second whale was observed off of Ship
Creek during 2021 PCT construction monitoring (61N Environmental,
2022a, Easley-Appleyard and Leonard, 2022). The whale observed in 2020
is believed to be the same whale that later stranded in the Twentymile
River, at the eastern end of Turnagain Arm, approximately 80 km
southeast of Knik Arm. There was no indication that work at the PCT had
any effect on the animal (see <a href="https://www.fisheries.noaa.gov/feature-story/alaska-gray-whale-ume-update-twentymile-river-whale-likely-one-twelve-dead-gray-whales">https://www.fisheries.noaa.gov/feature-story/alaska-gray-whale-ume-update-twentymile-river-whale-likely-one-twelve-dead-gray-whales</a> for more information). No gray whales were
observed during POA's transitional dredging or SFD construction
monitoring from May to August, 2022 (61N Environmental, 2022b, 2022c).
Humpback Whale
On September 8, 2016, NMFS divided the humpback whales into 14
distinct population segments (DPS) under the ESA, removed the species-
level listing as endangered, and, in its place, listed four DPSs as
endangered and one DPS as threatened (81 FR 62259, September 8, 2016).
The remaining nine DPSs were not listed. There are four DPSs in the
North Pacific, including Western North Pacific and Central America,
which are listed as endangered, Mexico, which is listed as threatened,
and Hawaii, which is not listed.
The 2022 Alaska and Pacific SARs described a revised stock
structure for humpback whales which modifies the previous stocks
designated under the MMPA to align more closely with the ESA-designated
DPSs (Carretta et al., 2023; Young et al., 2023). Specifically, the
three previous North Pacific humpback whale stocks (Central and Western
North Pacific stocks and a CA/OR/WA stock) were replaced by five
stocks, largely corresponding with the ESA-designated DPSs. These
include Western North Pacific and Hawaii stocks and a Central America/
Southern Mexico-CA/OR/WA stock (which corresponds with the Central
America DPS). The remaining two stocks, corresponding with the Mexico
DPS, are the Mainland Mexico-CA/OR/WA and Mexico-North Pacific stocks
(Carretta et al., 2023; Young et al., 2023). The former stock is
expected to occur along the west coast from California to southern
British Columbia, while the latter stock may occur across the Pacific,
from northern British Columbia through the Gulf of Alaska and Aleutian
Islands/Bering Sea region to Russia.
The Hawaii stock consists of one demographically independent
population (DIP) (Hawaii--Southeast Alaska/Northern British Columbia
DIP) and the Hawaii--North Pacific unit, which may or may not be
composed of multiple DIPs (Wade et al., 2021). The DIP and unit are
managed as a single stock at this time, due to the lack of data
available to separately assess them and lack of compelling conservation
benefit to managing them separately (NMFS, 2019, 2022b, 2023). The DIP
is delineated based on two strong lines of evidence: genetics and
movement data (Wade et al., 2021). Whales in the Hawaii--Southeast
Alaska/Northern British Columbia DIP winter off Hawaii and largely
summer in Southeast Alaska and Northern British Columbia (Wade et al.,
2021). The group of whales that migrate from Russia, western Alaska
(Bering Sea and Aleutian Islands), and central Alaska (Gulf of Alaska
excluding Southeast Alaska) to Hawaii have been delineated as the
Hawaii-North Pacific unit (Wade et al., 2021). There are a small number
of whales that migrate between Hawaii and southern British Columbia/
Washington, but current data and analyses do not provide a clear
understanding of which unit these whales belong to (Wade et al., 2021;
Carretta et al., 2023; Young et al., 2023).
The Mexico-North Pacific stock is likely composed of multiple DIPs,
based on movement data (Martien et al., 2021; Wade, 2021; Wade et al.,
2021). However, because currently available data and analyses are not
sufficient to delineate or assess DIPs within the unit, it was
designated as a single stock (NMFS, 2019, 2022c, 2023). Whales in
[[Page 76587]]
this stock winter off Mexico and the Revillagigedo Archipelago and
summer primarily in Alaska waters (Martien et al., 2021; Carretta et
al., 2023; Young et al., 2023).
The most comprehensive photo-identification data available suggest
that approximately 89 percent of all humpback whales in the Gulf of
Alaska are members of the Hawaii stock, 11 percent are from the Mexico
stock, and less than 1 percent are from the Western North Pacific stock
(Wade, 2021). Members of different stocks are known to intermix in
feeding grounds.
On October 9, 2019, NMFS proposed to designate critical habitat for
the Western North Pacific, Mexico, and Central America DPSs of humpback
whales (84 FR 54354). NMFS issued a final rule on April 21, 2021 to
designate critical habitat for ESA-listed humpback whales pursuant to
Section 4 of the ESA (86 FR 21082). There is no designated critical
habitat for humpback whales in or near the Project area (86 FR 21082,
April 21, 2021).
Humpback whales are encountered regularly in lower Cook Inlet and
occasionally in mid-Cook Inlet; however, sightings are rare in upper
Cook Inlet (e.g., Witteveen et al., 2011). During aerial surveys
conducted in summers between 2005 and 2012, Shelden et al. (2013)
reported dozens of sightings in lower Cook Inlet, a handful of
sightings in the vicinity of Anchor Point and in lower Cook Inlet, and
no sightings north of 60[deg] N latitude. NMFS changed to a biennial
survey schedule starting in 2014 after analysis showed there would be
little reduction in the ability to detect a trend given the current
growth rate of the population (Hobbs, 2013). No survey took place in
2020. Instead, consecutive surveys took place in 2021 and 2022 (Shelden
et al., 2022). During the 2014-2022 aerial surveys, sightings of
humpback whales were recorded in lower Cook Inlet and mid-Cook Inlet,
but none were observed in upper Cook Inlet (Shelden et al., 2015b,
2017, 2019, 2022). Vessel-based observers participating in the Apache
Corporation's 2014 survey operations recorded three humpback whale
sightings near Moose Point in upper Cook Inlet and two sightings near
Anchor Point, while aerial and land-based observers recorded no
humpback whale sightings, including in the upper inlet (Lomac-MacNair
et al., 2014). Observers monitoring waters between Point Campbell and
Fire Island during summer and fall 2011 and spring and summer 2012
recorded no humpback whale sightings (Brueggeman et al., 2013).
Monitoring of Turnagain Arm during ice-free months between 2006 and
2014 yielded one humpback whale sighting (McGuire, unpublished data,
cited in LGL Alaska Research Associates, Inc., and DOWL, 2015).
There have been few sightings of humpback whales in the vicinity of
the proposed project area. Humpback whales were not documented during
POA construction or scientific monitoring from 2005 to 2011, in 2016,
or during 2020 (Prevel-Ramos et al., 2006; Markowitz and McGuire, 2007;
Cornick and Saxon-Kendall, 2008, 2009; Cornick et al., 2010, 2011;
ICRC, 2009, 2010, 2011, 2012; Cornick and Pinney, 2011; Cornick and
Seagars, 2016; 61N Environmental, 2021). Observers monitoring the Ship
Creek Small Boat Launch from August 23 to September 11, 2017 recorded
two sightings, each of a single humpback whale, which was presumed to
be the same individual (POA, 2017). One other humpback whale sighting
has been recorded for the immediate vicinity of the project area. This
event involved a stranded whale that was sighted near a number of
locations in upper Cook Inlet before washing ashore at Kincaid Park in
2017; it is unclear as to whether the humpback whale was alive or
deceased upon entering Cook Inlet waters. Another juvenile humpback
stranded in Turnagain Arm in April 2019 near mile 86 of the Seward
Highway. One additional humpback whale was observed in July during 2022
transitional dredging monitoring (61N Environmental, 2022c). No
humpback whales were observed during the 2020 to 2021 PCT construction
monitoring, the NMFS marine mammal monitoring, or the 2022 SFD
construction monitoring from April to June (61N Environmental, 2021,
2022a, 2022b, 2022c; Easley-Appleyard and Leonard, 2022).
Beluga Whale
Five stocks of beluga whales are recognized in Alaska: the Beaufort
Sea stock, eastern Chukchi Sea stock, eastern Bering Sea stock, Bristol
Bay stock, and Cook Inlet stock (Young et al., 2023). The Cook Inlet
stock is geographically and genetically isolated from the other stocks
(O'Corry-Crowe et al., 1997; Laidre et al., 2000) and resides year-
round in Cook Inlet (Laidre et al., 2000; Castellote et al., 2020).
Only the Cook Inlet stock (CIBWs) inhabits the proposed project area.
CIBWs were designated as a DPS and listed as endangered under the ESA
in October 2008 (73 FR 62919, October 10, 2008).
Shelden and Wade (2019) analyzed time-series CIBW abundance data
from 2008 to 2018 and reported that the CIBW population was declining
at an annual rate of 2.3 percent during this time. Goetz et al., (2023)
suggest that this decline could have been part of a natural oscillation
in the population or possibly due to impacts of the unprecedented
heatwave in the Gulf of Alaska during the same time period. The CIBW
time-series abundance data were analyzed using a Bayesian statistical
method to estimate group size for calculating CIBW abundance. This
method produced an abundance estimate of 279 CIBWs, with a 95 percent
probability range of 250 to 317 whales (Shelden and Wade, 2019).
In June 2023, NMFS released an updated abundance estimate for CIBWs
in Alaska that incorporates aerial survey data from June 2021 and 2022
and accounted for visibility bias (i.e., availability bias due to
diving behavior; proximity bias due to individuals concealed by another
individual in the video data; perception bias due to individuals not
detected because of small image size in the video data; and individual
observer bias in visual observer data) (Goetz et al., 2023). This
report estimated that CIBW abundance is between 290 and 386, with a
median best estimate of 331. Goetz et al. (2023) also present an
analysis of population trends for the most recent 10-year period (2012-
2022). The addition of data from the 2021 and 2022 survey years in the
analysis resulted in a 65.1 percent probability that the CIBW
population is now increasing at 0.9 percent per year (95 percent
prediction interval of -3 to 5.7 percent). This increase drops slightly
to 0.2 percent per year (95 percent prediction interval of -1.8 to 2.6
percent) with a 60 percent probability that the CIBW population is
increasing more than 1 percent per year when data from 2021, which had
limited survey coverage due to poor weather, are excluded from the
analysis. Median group size estimates in 2021 and 2022 were 34 and 15,
respectively (Goetz et al., 2023). For management purposes, NMFS has
determined that the carrying capacity of Cook Inlet is 1,300 CIBWs (65
FR 34590, May 31, 2000) based on historical CIBW abundance estimated by
Calkins (1989).
Live stranding events of CIBWs have been regularly observed in
upper Cook Inlet. This can occur when an individual or group of
individuals strands as the tide recedes. Most live strandings have
occurred in Knik Arm and Turnagain Arm, which are shallow and have
large tidal ranges, strong currents, and extensive mudflats. Most
whales involved in a live stranding event survive, although some
associated deaths may not be observed if the whales die later from
live-stranding-
[[Page 76588]]
related injuries (Vos and Shelden, 2005; Burek-Huntington et al.,
2015). Between 2014 and 2018, there were reports of approximately 79
CIBWs involved in three known live stranding events, plus one suspected
live stranding event with two associated deaths reported (NMFS, 2016b;
NMFS, unpublished data; Muto et al., 2020). In 2014, necropsy results
from two whales found in Turnagain Arm suggested that a live stranding
event contributed to their deaths as both had aspirated mud and water.
No live stranding events were reported prior to the discovery of these
dead whales, suggesting that not all live stranding events are
observed.
Another source of CIBW mortality in Cook Inlet is predation by
transient-type (mammal-eating) killer whales (NMFS, 2016b; Shelden et
al., 2003). No human-caused mortality or serious injury of CIBWs
through interactions with commercial, recreational, and subsistence
fisheries, takes by subsistence hunters, and or human-caused events
(e.g., entanglement in marine debris, ship strikes) has been recently
documented and harvesting of CIBWs has not occurred since 2008 (NMFS,
2008b).
Recovery Plan. In 2010, a Recovery Team, consisting of a Science
Panel and Stakeholder Panel, began meeting to develop a Recovery Plan
for the CIBW. The Final Recovery Plan was published in the Federal
Register on January 5, 2017 (82 FR 1325). In September 2022, NMFS
completed the ESA 5-year review for the CIBW DPS and determined that
the CIBW DPS should remain listed as endangered (NMFS, 2022d).
In its Recovery Plan (82 FR 1325, January 5, 2017), NMFS identified
several potential threats to CIBWs, including: (1) high concern:
catastrophic events (e.g., natural disasters, spills, mass strandings),
cumulative effects of multiple stressors, and noise; (2) medium
concern: disease agents (e.g., pathogens, parasites, and harmful algal
blooms), habitat loss or degradation, reduction in prey, and
unauthorized take; and (3) low concern: pollution, predation, and
subsistence harvest. The recovery plan did not treat climate change as
a distinct threat but rather as a consideration in the threats of high
and medium concern. Other potential threats most likely to result in
direct human-caused mortality or serious injury of this stock include
vessel strikes.
Critical Habitat. On April 11, 2011, NMFS designated two areas of
critical habitat for CIBW (76 FR 20179). The designation includes 7,800
km\2\ of marine and estuarine habitat within Cook Inlet, encompassing
approximately 1,909 km\2\ in Area 1 and 5,891 km\2\ in Area 2 (see
Figure 1 in 76 FR 20179). Area 1 of the CIBW critical habitat
encompasses all marine waters of Cook Inlet north of a line connecting
Point Possession (lat. 61.04[deg] N, long. 150.37[deg] W) and the mouth
of Three Mile Creek (lat. 61.08.55[deg] N, long. 151.04.40[deg] W),
including waters of the Susitna, Little Susitna, and Chickaloon Rivers
below mean higher high water. From spring through fall, Area 1 critical
habitat has the highest concentration of CIBWs due to its important
foraging and calving habitat. Area 2 critical habitat has a lower
concentration of CIBWs in spring and summer but is used by CIBWs in
fall and winter. Critical habitat does not include two areas of
military usage: the Eagle River Flats Range on Fort Richardson and
military lands of JBER between Mean Higher High Water and MHW.
Additionally, the POA, adjacent navigation channel, and turning basin
were excluded from critical habitat designation due to national
security reasons (76 FR 20180, April 11, 2011). The POA exclusion area
is within Area 1, however, marine mammal monitoring results from the
POA suggest that this exclusion area is not a particularly important
feeding or calving area. CIBWs have been occasionally documented to
forage around Ship Creek (south of the POA) but are typically
transiting through the area to other, potentially richer, foraging
areas to the north (e.g., Six Mile Creek, Eagle River, Eklutna River)
(e.g., 61N Environmental, 2021, 2022a, 2022b, 2022c, Easley-Appleyard
and Leonard, 2022). These locations contain predictable salmon runs, an
important food source for CIBWs, and the timing of these runs has been
correlated with CIBW movements into the upper reaches of Knik Arm (Ezer
et al., 2013). More information on CIBW critical habitat can be found
at <a href="https://www.fisheries.noaa.gov/action/critical-habitat-cook-inlet-beluga-whale">https://www.fisheries.noaa.gov/action/critical-habitat-cook-inlet-beluga-whale</a>.
The designation identified the following Primary Constituent
Elements, essential features important to the conservation of the CIBW:
(1) Intertidal and subtidal waters of Cook Inlet with depths of
less than 9 m (MLLW) and within 8 km of high- and medium-flow
anadromous fish streams;
(2) Primary prey species, including four of the five species of
Pacific salmon (chum (Oncorhynchus keta), sockeye (Oncorhynchus nerka),
Chinook (Oncorhynchus tshawytscha), and coho (Oncorhynchus kisutch)),
Pacific eulachon (Thaleichthys pacificus), Pacific cod (Gadus
macrocephalus), walleye Pollock (Gadus chalcogrammus), saffron cod
(Eleginus gracilis), and yellowfin sole (Limanda aspera);
(3) The absence of toxins or other agents of a type or amount
harmful to CIBWs;
(4) Unrestricted passage within or between the critical habitat
areas; and
(5) The absence of in-water noise at levels resulting in the
abandonment of habitat by CIBWs.
Biologically Important Areas. Wild et al. (2023) delineated
portions of Cook Inlet, including near the proposed project area, as a
Biologically Important Area (BIA) for the small and resident population
of CIBWs based on scoring methods outlined by Harrison et al. (2023)
(see <a href="https://oceannoise.noaa.gov/biologically-important-areas">https://oceannoise.noaa.gov/biologically-important-areas</a> for more
information). The BIA is used year-round by CIBWs for feeding and
breeding, and there are limits on food supply such as salmon runs and
seasonal movement of other fish species (Wild et al., 2023). The
boundary of the CIBW BIA is consistent with NMFS' critical habitat
designation, and does not include the aforementioned exclusion areas
(e.g., the POA and surrounding waters) (Wild et al., 2023).
Foraging Ecology. CIBWs feed on a wide variety of prey species,
particularly those that are seasonally abundant. From late spring
through summer, most CIBW stomachs sampled contained salmon, which
corresponded to the timing of fish runs in the area. Anadromous smolt
and adult fish aggregate at river mouths and adjacent intertidal
mudflats (Calkins, 1989). All five Pacific salmon species (i.e.,
Chinook, pink (Oncorhynchus gorbuscha), coho, sockeye, and chum) spawn
in rivers throughout Cook Inlet (Moulton, 1997; Moore et al., 2000).
Overall, Pacific salmon represent the highest percent frequency of
occurrence of prey species in CIBW stomachs. This suggests that their
spring feeding in upper Cook Inlet, principally on fat-rich fish such
as salmon and eulachon, is important to the energetics of these animals
(NMFS, 2016b).
The nutritional quality of Chinook salmon in particular is
unparalleled, with an energy content four times greater than that of a
Coho salmon. It is suggested the decline of the Chinook salmon
population has left a nutritional void in the diet of the CIBWs that no
other prey species can fill in terms of quality or quantity (Norman et
al., 2020, 2022).
In fall, as anadromous fish runs begin to decline, CIBWs return to
consume fish species (cod and bottom fish) found in nearshore bays and
estuaries. Stomach samples from CIBWs are not available for winter
(December through
[[Page 76589]]
March), although dive data from CIBWs tagged with satellite
transmitters suggest that they feed in deeper waters during winter
(Hobbs et al., 2005), possibly on such prey species as flatfish, cod,
sculpin, and pollock.
Distribution in Cook Inlet. The CIBW stock remains within Cook
Inlet throughout the year, showing only small seasonal shifts in
distribution (Goetz et al., 2012a; Lammers et al., 2013; Castallotte et
al., 2015; Shelden et al., 2015a, 2018; Lowery et al., 2019). During
spring and summer, CIBWs generally aggregate near the warmer waters of
river mouths where prey availability is high and predator occurrence is
low (Moore et al., 2000; Shelden and Wade, 2019; McGuire et al., 2020).
In particular, CIBW groups are seen in the Susitna River Delta, the
Beluga River and along the shore to the Little Susitna River, Knik Arm,
and along the shores of Chickaloon Bay. Small groups were recorded
farther south in Kachemak Bay, Redoubt Bay (Big River), and Trading Bay
(McArthur River) prior to 1996, but rarely thereafter. Since the mid-
1990s, most CIBWs (96 to 100 percent) aggregate in shallow areas near
river mouths in upper Cook Inlet, and they are only occasionally
sighted in the central or southern portions of Cook Inlet during summer
(Hobbs et al., 2008). Almost the entire population can be found in
northern Cook Inlet from late spring through the summer and into the
fall (Muto et al., 2020).
Data from tagged whales (14 tags deployed July 2000 through March
2003) show that CIBWs use upper Cook Inlet intensively between summer
and late autumn (Hobbs et al., 2005). CIBWs tagged with satellite
transmitters continue to use Knik Arm, Turnagain Arm, and Chickaloon
Bay as late as October, but some range into lower Cook Inlet to
Chinitna Bay, Tuxedni Bay, and Trading Bay (McArthur River) in fall
(Hobbs et al., 2005, 2012). From September through November, CIBWs move
between Knik Arm, Turnagain Arm, and Chickaloon Bay (Hobbs et al.,
2005; Goetz et al., 2012b). By December, CIBWs are distributed
throughout the upper to mid-inlet. From January into March, they move
as far south as Kalgin Island and slightly beyond in central offshore
waters. CIBWs make occasional excursions into Knik Arm and Turnagain
Arm in February and March in spite of ice cover (Hobbs et al., 2005).
Although tagged CIBWs move widely around Cook Inlet throughout the
year, there is no indication of seasonal migration in and out of Cook
Inlet (Hobbs et al., 2005). Data from NMFS aerial surveys,
opportunistic sighting reports, and corrected satellite-tagged CIBWs
confirm that they are more widely dispersed throughout Cook Inlet
during winter (November-April), with animals found between Kalgin
Island and Point Possession. Generally fewer observations of CIBWs are
reported from the Anchorage and Knik Arm area from November through
April (76 FR 20179, April 11, 2011; Rugh et al., 2000, 2004).
The NMFS Marine Mammal Lab has conducted long-term passive acoustic
monitoring demonstrating seasonal shifts in CIBW concentrations
throughout Cook Inlet. Castellote et al. (2015) conducted long-term
acoustic monitoring at 13 locations throughout Cook Inlet between 2008
and 2015: North Eagle Bay, Eagle River Mouth, South Eagle Bay, Six
Mile, Point MacKenzie, Cairn Point, Fire Island, Little Susitna, Beluga
River, Trading Bay, Kenai River, Tuxedni Bay, and Homer Spit; the
former six stations being located within Knik Arm. In general, the
observed seasonal distribution is in accordance with descriptions based
on aerial surveys and satellite telemetry: CIBW detections are higher
in the upper inlet during summer, peaking at Little Susitna, Beluga
River, and Eagle Bay, followed by fewer detections at those locations
during winter. Higher detections in winter at Trading Bay, Kenai River,
and Tuxedni Bay suggest a broader CIBW distribution in the lower inlet
during winter.
Goetz et al. (2012b) modeled habitat preferences using NMFS' 1994-
2008 June abundance survey data. In large areas, such as the Susitna
Delta (Beluga to Little Susitna Rivers) and Knik Arm, there was a high
probability that CIBWs were in larger groups. CIBW presence and
acoustic foraging behavior also increased closer to rivers with Chinook
salmon runs, such as the Susitna River (e.g., Castellote et al., 2021).
Movement has been correlated with the peak discharge of seven major
rivers emptying into Cook Inlet. Boat-based surveys from 2005 to the
present (McGuire and Stephens, 2017) and results from passive acoustic
monitoring across the entire inlet (Castellote et al., 2015) also
support seasonal patterns observed with other methods. Based on long-
term passive acoustic monitoring, seasonally, foraging behavior was
more prevalent during summer, particularly at upper inlet rivers, than
during winter. Foraging index was highest at Little Susitna, with a
peak in July[hyphen]August and a secondary peak in May, followed by
Beluga River and then Eagle Bay; monthly variation in the foraging
index indicates CIBWs shift their foraging behavior among these three
locations from April through September.
CIBWs are believed to mostly calve in the summer, and concurrently
breed between late spring and early summer (NMFS, 2016b), primarily in
upper Cook Inlet. The only known observed occurrence of calving
occurred on July 20, 2015, in the Susitna Delta area (T. McGuire,
personal communication, March 27, 2017). The first neonates encountered
during each field season from 2005 through 2015 were always seen in the
Susitna River Delta in July. The photographic identification team's
documentation of the dates of the first neonate of each year indicate
that calving begins in mid-late July/early August, generally coinciding
with the observed timing of annual maximum group size. Probable mating
behavior of CIBWs was observed in April and May of 2014, in Trading
Bay. Young CIBWs are nursed for 2 years and may continue to associate
with their mothers for a considerable time thereafter (Colbeck et al.,
2013). Important calving grounds are thought to be located near the
river mouths of upper Cook Inlet.
Presence in Project Area. Knik Arm is one of three areas in upper
Cook Inlet where CIBWs are concentrated during spring, summer, and
early fall. Most CIBWs observed in or near the POA are transiting
between upper Knik Arm and other portions of Cook Inlet, and the POA
itself is not considered high-quality foraging habitat. CIBWs tend to
follow their anadromous prey and travel in and out of Knik Arm with the
tides. The predictive habitat model derived by Goetz et al. (2012a)
indicated that CIBW density ranges from 0 to 1.12 whales per km\2\ in
Cook Inlet. The highest predicted densities of CIBWs are in Knik Arm,
near the mouth of the Susitna River, and in Chickaloon Bay. The model
suggests that the density of CIBWs at the mouth of Knik Arm, near the
POA, ranges between approximately 0.013 and 0.062 whales per km\2\. The
distribution presented by Goetz et al. (2012a) is generally consistent
with CIBW distribution documented in upper Cook Inlet throughout ice-
free months (NMFS, 2016b).
Several marine mammal monitoring programs and studies have been
conducted at or near the POA during the last 17 years. These studies
offer some of the best available information on the presence of CIBWs
in the proposed project area. Studies that occurred prior to 2020 are
summarized in Section 4.5.5 of the POA's application. More recent
programs, which most accurately portray current information regarding
CIBW presence in the proposed project area, are summarized here.
[[Page 76590]]
PCT Construction Monitoring (2020-2021). A marine mammal monitoring
program was implemented during construction of the PCT in 2020 (Phase
1) and 2021 (Phase 2), as required by the NMFS IHAs (85 FR 19294, April
6, 2020). PCT Phase 1 construction included impact installation of 48-
inch (122-cm) attenuated piles; impact installation of 36-inch (91-cm)
and 48-inch (122-cm) unattenuated piles; vibratory installation of 24-
inch (61-cm), 36-inch (91-cm), and 48-inch (122 cm) attenuated and
unattenuated piles; and vibratory installation of an unattenuated 72-
inch (183-cm) bubble curtain across 95 days. PCT Phase 2 construction
included vibratory installation of 36-inch (91-cm) attenuated piles and
impact and vibratory installation of 144-inch (366-cm) attenuated
breasting and mooring dolphins across 38 days. Marine mammal monitoring
in 2020 occurred during 128 non-consecutive days, with a total of
1,238.7 hours of monitoring from April 27 to November 24, 2020 (61N
Environmental, 2021). Marine mammal monitoring in 2021 occurred during
74 non-consecutive days, with a total of 734.9 hours of monitoring from
April 26 to June 24 and September 7 to 29, 2021 (61N Environmental,
2022a). A total of 1,504 individual CIBWs across 377 groups were
sighted during PCT construction monitoring. Sixty-five and sixty-seven
percent of CIBW observations occurred on non-pile driving days or
before pile driving occurred on a given day during PCT Phase 1 and PCT
Phase 2 construction, respectively.
The monitoring effort and data collection were conducted before,
during, and after pile driving activities from four locations as
stipulated by the PCT IHAs (85 FR 19294, April 6, 2020): (1) the
Anchorage Public Boat Dock by Ship Creek, (2) the Anchorage Downtown
Viewpoint near Point Woronzof, (3) the PCT construction site, and (4)
the North End (North Extension) at the north end of the POA, near Cairn
Point. Marine mammal sighting data from April to September both before,
during, and after pile driving indicate that CIBWs swam near the POA
and lingered there for periods of time ranging from a few minutes to a
few hours. CIBWs were most often seen traveling at a slow or moderate
pace, either from the north near Cairn Point or from the south or
milling at the mouth of Ship Creek. Groups of CIBWs were also observed
swimming north and south in front of the PCT construction, and did not
appear to exhibit avoidance behaviors either before, during, or after
pile driving activities (61N Environmental, 2021, 2022a). CIBW
sightings in June were concentrated on the west side of Knik Arm from
the Little Susitna River Delta to Port MacKenzie. From July through
September, CIBWs were most often seen milling and traveling on the east
side of Knik Arm from Point Woronzof to Cairn Point (61N Environmental,
2021, 2022a).
SFD Construction Monitoring and Transitional Dredging (2022). In
2022, a marine mammal monitoring program almost identical to that used
during PCT construction was implemented during construction of the SFD,
as required by the NMFS IHA (86 FR 50057, September 7, 2021). SFD
construction included the vibratory installation of ten 36-inch (91-cm)
attenuated plumb piles and two unattenuated battered piles (61N
Environmental, 2022b). Marine mammal monitoring was conducted during 13
non-consecutive days, with a total of 108.2 hours of monitoring
observation from May 20 through June 11, 2022 (61N Environmental,
2022b). Forty-one individual CIBWs across 9 groups were sighted (61N
Environmental, 2022b). One group was observed on a day with no pile-
driving, three groups were seen on days before pile driving activities
started, and five groups were seen during vibratory pile driving
activities (61N Environmental, 2022b).
During SFD construction, the position of the Ship Creek monitoring
station was adjusted to allow monitoring of a portion of the shoreline
north of Cairn Point that could not be seen by the station at the
northern end of the POA (61N Environmental, 2022b). Eleven protected
species observers (PSOs) worked from four monitoring stations located
along a 9-km (6-mi) stretch of coastline surrounding the POA. The
monitoring effort and data collection were conducted at the following
four locations: (1) Point Woronzof approximately 6.5 km (4 mi)
southwest of the SFD, (2) the promontory near the boat launch at Ship
Creek, (3) the SFD project site, and (4) the northern end of the POA
(61N Environmental, 2022b).
Ninety groups comprised of 529 CIBWs were also sighted during the
transitional dredging monitoring that occurred from May 3 to 15, 2022
and June 27 to August 24, 2022 (61N Environmental, 2022b). Of the nine
groups of CIBWs sighted during SFD construction, traveling was recorded
as the primary behavior for each group (61N Environmental, 2022b).
CIBWs traveled and milled between the SFD construction area, Ship
Creek, and areas to the south of the POA for more than an hour at a
time, delaying some construction activities.
Killer Whale
Along the west coast of North America, seasonal and year-round
occurrence of killer whales has been noted along the entire Alaska
coast (Braham and Dahlheim, 1982), in British Columbia and Washington
inland waterways (Bigg et al., 1990), and along the outer coasts of
Washington, Oregon, and California (Green et al., 1992; Barlow 1995,
1997; Forney et al., 1995). Killer whales from these areas have been
labeled as ``resident,'' ``transient,'' and ``offshore'' type killer
whales (Bigg et al., 1990; Ford et al., 2000; Dahlheim et al., 2008)
based on aspects of morphology, ecology, genetics, and behavior (Ford
and Fisher, 1982; Baird and Stacey, 1988; Baird et al., 1992; Hoelzel
et al., 1998, 2002; Barrett Lennard, 2000; Dahlheim et al., 2008).
Based on data regarding association patterns, acoustics, movements, and
genetic differences, eight killer whale stocks are now recognized
within the U.S. Pacific, two of which have the potential to be found in
the proposed project area: the Eastern North Pacific Alaska Resident
stock and the Gulf of Alaska, Aleutian Islands, and the Bering Sea
Transient stock. Both stocks overlap the same geographic area; however,
they maintain social and reproductive isolation and feed on different
prey species. Resident killer whales are primarily fish-eaters, while
transients primarily hunt and consume marine mammals, such as harbor
seals, Dall's porpoises, harbor porpoises, beluga whales and sea lions.
Killer whales are not harvested for subsistence in Alaska. Potential
threats most likely to result in direct human-caused mortality or
serious injury of killer whales in this region include oil spills,
vessel strikes, and interactions with fisheries.
Killer whales are rare in Cook Inlet, and most individuals are
observed in lower Cook Inlet (Shelden et al., 2013). The infrequent
sightings of killer whales that are reported in upper Cook Inlet tend
to occur when their primary prey (anadromous fish for resident killer
whales and beluga whales for transient killer whales) are also in the
area (Shelden et al., 2003). During CIBW aerial surveys between 1993
and 2012, killer whales were sighted in lower Cook Inlet 17 times, with
a total of 70 animals (Shelden et al., 2013); no killer whales were
observed in upper Cook Inlet during this time. Surveys over 20 years by
Shelden et al. (2003) documented an increase in CIBW sightings and
strandings in upper Cook Inlet beginning in the early 1990s. Several of
these sightings and strandings reported evidence of killer whale
[[Page 76591]]
predation on CIBWs. The pod sizes of killer whales preying on CIBWs
ranged from one to six individuals (Shelden et al., 2003). Passive
acoustic monitoring efforts throughout Cook Inlet documented killer
whales at the Beluga River, Kenai River, and Homer Spit, although they
were not encountered within Knik Arm (Castellote et al., 2016). These
detections were likely resident killer whales. Transient killer whales
likely have not been acoustically detected due to their propensity to
move quietly through waters to track prey (Small, 2010; Lammers et al.,
2013).
Few killer whales, if any, are expected to approach or be in the
vicinity of the proposed project area. No killer whales were spotted in
the vicinity of the POA during surveys by Funk et al. (2005), Ireland
et al. (2005), or Brueggeman et al. (2007, 2008a, 2008b). Killer whales
have also not been documented during any POA construction or scientific
monitoring from 2005 to 2011, in 2016, or in 2020 (Prevel-Ramos et al.,
2006; Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 2008;
ICRC, 2009, 2010, 2011, 2012; Cornick et al., 2010, 2011; Cornick and
Pinney, 2011; Cornick and Seagars, 2016; 61N Environmental, 2021). Two
killer whales, one male and one juvenile of unknown sex, were sighted
offshore of Point Woronzof in September 2021 during PCT Phase 2
construction monitoring (61N Environmental, 2022a). The pair of killer
whales moved up Knik Arm, reversed direction near Cairn Point, and
moved southwest out of Knik Arm toward the open water of Upper Cook
Inlet. No killer whales were sighted during the 2021 NMFS marine mammal
monitoring or the 2022 transitional dredging and SFD construction
monitoring that occurred between May and June 2022 (61N Environmental,
2022b, 2022c; Easley-Appleyard and Leonard, 2022).
Harbor Porpoise
In the eastern North Pacific Ocean, harbor porpoise range from
Point Barrow, along the Alaska coast, and down the west coast of North
America to Point Conception, California. The 2022 Alaska SARs describe
a revised stock structure for harbor porpoises (Young et al., 2023).
Previously, NMFS had designated three stocks of harbor porpoises: the
Bering Sea stock, the Gulf of Alaska stock, and the Southeast Alaska
stock (Muto et al., 2022; Zerbini et al., 2022). The 2022 Alaska SARs
splits the Southeast Alaska stock into three separate stocks, resulting
in five separate stocks in Alaskan waters for this species. This update
better aligns harbor porpoise stock structure with genetics, trends in
abundance, and information regarding discontinuous distribution trends
(Young et al., 2023). Harbor porpoises found in Cook Inlet are assumed
to be members of the Gulf of Alaska stock (Young et al., 2023).
Harbor porpoises occur most frequently in waters less than 100 m
deep (Hobbs and Waite, 2010). They can be opportunistic foragers but
consume primarily schooling forage fish (Bowen and Siniff, 1999). Given
their shallow water distribution, harbor porpoise are vulnerable to
physical modifications of nearshore habitats resulting from urban and
industrial development (including waste management and nonpoint source
runoff) and activities such as construction of docks and other over-
water structures, filling of shallow areas, dredging, and noise
(Linnenschmidt et al., 2013). Subsistence users have not reported any
harvest from the Gulf of Alaska harbor porpoise stock since the early
1900s (Shelden et al., 2014). Calving occurs from May to August;
however, this can vary by region. Harbor porpoises are often found
traveling alone, or in small groups of less than 10 individuals
(Schmale, 2008).
Harbor porpoises occur throughout Cook Inlet, with passive acoustic
detections being more prevalent in lower Cook Inlet. Although harbor
porpoises have been frequently observed during aerial surveys in Cook
Inlet (Shelden et al., 2014), most sightings are of single animals and
are concentrated at Chinitna and Tuxedni bays on the west side of lower
Cook Inlet (Rugh et al., 2005). The occurrence of larger numbers of
porpoise in the lower Cook Inlet may be driven by greater availability
of preferred prey and possibly less competition with CIBWs, as CIBWs
move into upper inlet waters to forage on Pacific salmon during the
summer months (Shelden et al., 2014).
An increase in harbor porpoise sightings in upper Cook Inlet was
observed over recent decades (e.g., 61N Environmental, 2021, 2022a;
Shelden et al., 2014). Small numbers of harbor porpoises have been
consistently reported in upper Cook Inlet between April and October
(Prevel-Ramos et al., 2008). The overall increase in the number of
harbor porpoise sightings in upper Cook Inlet is unknown, although it
may be an artifact from increased studies and marine mammal monitoring
programs in upper Cook Inlet. It is also possible that the contraction
in the CIBW's range has opened up previously occupied CIBW range to
harbor porpoises (Shelden et al., 2014).
Harbor porpoises have been observed within Knik Arm during
monitoring efforts from 2005 to 2016. Between April 27 and November 24,
2020, 18 harbor porpoises were observed near the POA during the PCT
Phase 1 construction monitoring (61N Environmental, 2021). Twenty-seven
harbor porpoises were observed near the POA during the PCT Phase 2
construction monitoring conducted between April 26 and September 29,
2021 (61N Environmental, 2022a). During NMFS marine mammal monitoring
conducted in 2021, one harbor porpoise was observed in August and six
harbor porpoises were observed in October (Easley-Appleyard and
Leonard, 2022). During 2022, five harbor porpoises were sighted during
transitional dredging monitoring (61N Environmental, 2022c). No harbor
porpoises were sighted at the POA during the 2022 SFD construction
monitoring that occurred between May and June 2022 (61N Environmental,
2022b).
Steller Sea Lion
Two Distinct Population Segments (DPSs) of Steller sea lion occur
in Alaska: the western DPS and the eastern DPS. The western DPS
includes animals that occur west of Cape Suckling, Alaska, and
therefore includes individuals within the Project area. The western DPS
was listed under the ESA as threatened in 1990 (55 FR 49204, November
26, 1990), and its continued population decline resulted in a change in
listing status to endangered in 1997 (62 FR 24345, May 5, 1997). Since
2000, studies indicate that the population east of Samalga Pass (i.e.,
east of the Aleutian Islands) has increased and is potentially stable
(Young et al., 2023).
There is uncertainty regarding threats currently impeding the
recovery of Steller sea lions, particularly in the Aleutian Islands.
Many factors have been suggested as causes of the steep decline in
abundance of western Steller sea lions observed in the 1980s, including
competitive effects of fishing, environmental change, disease,
contaminants, killer whale predation, incidental take, and illegal and
legal shooting (Atkinson et al., 2008; NMFS, 2008a). A number of
management actions have been implemented since 1990 to promote the
recovery of the Western U.S. stock of Steller sea lions, including 5.6-
km (3-nautical mile) no-entry zones around rookeries, prohibition of
shooting at or near sea lions, and regulation of fisheries for sea lion
prey species (e.g., walleye pollock, Pacific cod, and Atka mackerel
(Pleurogrammus monopterygius)) (Sinclair et al., 2013; Tollit et al.,
2017). Additionally, potentially deleterious events, such as harmful
algal blooms
[[Page 76592]]
(Lefebvre et al., 2016) and disease transmission across the Arctic
(VanWormer et al., 2019) that have been associated with warming waters,
could lead to potentially negative population-level impacts on Steller
sea lions.
NMFS designated critical habitat for Steller sea lions on August
27, 1993 (58 FR 45269). The critical habitat designation for the
Western DPS of was determined to include a 37-km (20-nautical mile)
buffer around all major haul-outs and rookeries, and associated
terrestrial, atmospheric, and aquatic zones, plus three large offshore
foraging areas, none of which occurs in the project area.
Steller sea lions are opportunistic predators, feeding primarily on
a wide variety of seasonally abundant fishes and cephalopods, including
Pacific herring (Clupea pallasi), walleye pollock, capelin (Mallotus
villosus), Pacific sand lance (Ammodytes hexapterus), Pacific cod,
salmon (Oncorhynchus spp.), and squid (Teuthida spp.); (Jefferson et
al., 2008; Wynne et al., 2011). Steller sea lions do not generally eat
every day, but tend to forage every 1-2 days and return to haulouts to
rest between foraging trips (Merrick and Loughlin, 1997; Rehberg et
al., 2009). Steller sea lions feed largely on walleye pollock, salmon,
and arrowtooth flounder during the summer, and walleye pollock and
Pacific cod during the winter (Sinclair and Zeppelin, 2002). Except for
salmon, none of these are found in abundance in upper Cook Inlet
(Nemeth et al., 2007).
Within Cook Inlet, Steller sea lions primarily inhabit lower Cook
Inlet. However, they occasionally venture to upper Cook Inlet and Knik
Arm and may be attracted to salmon runs in the region. Steller sea
lions have not been documented in upper Cook Inlet during CIBW aerial
surveys conducted annually in June from 1994 through 2012 and in 2014
(Shelden et al., 2013, 2015b, 2017; Shelden and Wade, 2019); however,
there has been an increase in individual Steller sea lion sightings
near the POA in recent years.
Steller sea lions were observed near the POA in 2009, 2016, and
2019 through 2022 (ICRC, 2009; Cornick and Seagars, 2016; POA, 2019;
61N Environmental, 2021, 2022a, 2022b, 2022c). In 2009, there were
three Steller sea lion sightings that were believed to be the same
individual (ICRC, 2009). In 2016, Steller sea lions were observed on 2
separate days. On May 2, 2016, one individual was sighted, while on May
25, 2016, there were five Steller Sea lion sightings within a 50-minute
period, and these sightings occurred in areas relatively close to one
another (Cornick and Seagars, 2016). Given the proximity in time and
space, it is believed these five sightings were of the same individual
sea lion. In 2019, one Steller sea lion was observed in June at the POA
during transitional dredging (POA, 2019). There were six sightings of
individual Steller sea lions near the POA during PCT Phase 1
construction monitoring (61N Environmental, 2021). At least two of
these sightings may have been re-sights on the same individual. An
additional seven unidentified pinnipeds were observed that could have
been Steller sea lions or harbor seals (61N Environmental, 2021). In
2021, there were a total of eight sightings of individual Steller sea
lions observed near the POA during PCT Phase 2 construction monitoring
(61N Environmental, 2022a). During NMFS marine mammal monitoring, one
Steller sea lion was observed in August 2021 in the middle of the inlet
(Easley-Appleyard and Leonard, 2022). In 2022, there were three Steller
sea lion sightings during the transitional dredging monitoring and
three during SFD construction monitoring (61N Environmental, 2022b,
2022c). All sightings occurred during summer, when the sea lions were
likely attracted to ongoing salmon runs. Sea lion observations near the
POA may be increasing due to more consistent observation effort or due
to increased presence; observations continue to be occasional.
Harbor Seal
Harbor seals inhabit waters all along the western coast of the
United States, British Columbia, and north through Alaska waters to the
Pribilof Islands and Cape Newenham. NMFS currently identifies 12 stocks
of harbor seals in Alaska based largely on genetic structure (Young et
al., 2023). Harbor seals in the proposed project area are members of
the Cook Inlet/Shelikof stock, which ranges from the southwest tip of
Unimak Island east along the southern coast of the Alaska Peninsula to
Elizabeth Island off the southwest tip of the Kenai Peninsula,
including Cook Inlet, Knik Arm, and Turnagain Arm. Distribution of the
Cook Inlet/Shelikof stock extends from Unimak Island, in the Aleutian
Islands archipelago, north through all of upper and lower Cook Inlet
(Young et al., 2023).
Harbor seals forage in marine, estuarine, and occasionally
freshwater habitat. They are opportunistic feeders that adjust their
local distribution to take advantage of locally and seasonally abundant
prey (Baird, 2001; Bj[oslash]rge, 2002). In Cook Inlet, harbor seals
have been documented in higher concentrations near steelhead
(Oncorhynchus mykiss), Chinook, and salmon spawning streams during
summer and may target more offshore prey species during winter (Boveng
et al., 2012).
Harbor seals haul out on rocks, reefs, beaches, and drifting
glacial ice (Young et al., 2023). Their movements are influenced by
tides, weather, season, food availability, and reproduction, as well as
individual sex and age class (Lowry et al., 2001; Small et al., 2003;
Boveng et al., 2012). The results of past and recent satellite tagging
studies in Southeast Alaska, Prince William Sound, Kodiak Island, and
Cook Inlet are also consistent with the conclusion that harbor seals
are non-migratory (Lowry et al., 2001; Small et al., 2003; Boveng et
al., 2012). However, some long-distance movements of tagged animals in
Alaska have been recorded (Pitcher and McAllister, 1981; Lowry et al.,
2001; Small et al., 2003; Womble, 2012; Womble and Gende, 2013). Strong
fidelity of individuals for haul-out sites during the breeding season
has been documented in several populations (H[auml]rk[ouml]nen and
Harding, 2001), including some regions in Alaska such as Kodiak Island,
Prince William Sound, Glacier Bay/Icy Strait, and Cook Inlet (Pitcher
and McAllister, 1981; Small et al., 2005; Boveng et al., 2012; Womble,
2012; Womble and Gende, 2013). Harbor seals usually give birth to a
single pup between May and mid-July; birthing locations are dispersed
over several haulout sites and not confined to major rookeries
(Klinkhart et al., 2008).
Harbor seals inhabit the coastal and estuarine waters of Cook Inlet
and are observed in both upper and lower Cook Inlet throughout most of
the year (Boveng et al., 2012; Shelden et al., 2013). Recent research
on satellite-tagged harbor seals observed several movement patterns
within Cook Inlet (Boveng et al., 2012), including a strong seasonal
pattern of more coastal and restricted spatial use during the spring
and summer (breeding, pupping, molting) and more wide-ranging movements
within and outside of Cook Inlet during the winter months, with some
seals ranging as far as Shumagin Islands. During summer months,
movements and distribution were mostly confined to the west side of
Cook Inlet and Kachemak Bay, and seals captured in lower Cook Inlet
generally exhibited site fidelity by remaining south of the Forelands
in lower Cook Inlet after release (Boveng et al., 2012). In the fall, a
portion of the harbor seals appeared to move out of Cook Inlet and into
Shelikof Strait, northern Kodiak Island, and coastal habitats of the
[[Page 76593]]
Alaska Peninsula. The western coast of Cook Inlet had higher usage by
harbor seals than eastern coast habitats, and seals captured in lower
Cook Inlet generally exhibited site fidelity by remaining south of the
Forelands in lower Cook Inlet after release (south of Nikiski; Boveng
et al., 2012).
The presence of harbor seals in upper Cook Inlet is seasonal.
Harbor seals are commonly observed along the Susitna River and other
tributaries within upper Cook Inlet during eulachon and salmon
migrations (NMFS, 2003). The major haulout sites for harbor seals are
in lower Cook Inlet; however, there are a few haulout sites in upper
Cook Inlet, including near the Little and Big Susitna rivers, Beluga
River, Theodore River, and Ivan River (Barbara Mahoney, personal
communication, November 16, 2020; Montgomery et al., 2007). During CIBW
aerial surveys of upper Cook Inlet from 1993 to 2012, harbor seals were
observed 24 to 96 km south-southwest of Anchorage at the Chickaloon,
Little Susitna, Susitna, Ivan, McArthur, and Beluga rivers (Shelden et
al., 2013). Harbor seals have been observed in Knik Arm and in the
vicinity of the POA (Shelden et al., 2013), but they are not known to
haul out within the proposed project area.
Harbor seals were observed during construction monitoring at the
POA from 2005 through 2011 and in 2016 (Prevel-Ramos et al., 2006;
Markowitz and McGuire, 2007; Cornick and Saxon-Kendall, 2008, 2009;
Cornick et al., 2010, 2011). Harbor seals were observed in groups of
one to seven individuals (Cornick et al., 2011; Cornick and Seagars,
2016). Harbor seals were also observed near the POA during construction
monitoring for PCT Phase 1 in 2020 and PCT Phase 2 in 2021, NMFS marine
mammal monitoring in 2021, and transitional dredging monitoring and SFD
construction monitoring in 2022 (61N Environmental, 2021, 2022a, 2022b,
2022c, Easley-Appleyard and Leonard, 2022). During the 2020 PCT Phase 1
and 2021 PCT Phase 2 construction monitoring, harbor seals were
regularly observed in the vicinity of the POA with frequent
observations near the mouth of Ship Creek, located approximately 2,500
m southeast of the NES1 location. Harbor seals were observed almost
daily during 2020 PCT Phase 1 construction, with 54 individuals
documented in July, 66 documented in August, and 44 sighted in
September (61N Environmental, 2021). During the 2021 PCT Phase 2
construction, harbor seals were observed with the highest numbers of
sightings in June (87 individuals) and in September (124 individuals)
(61 N Environmental, 2022a). Over the 13 days of SFD construction
monitoring in May and June 2022, 27 harbor seals were observed (61N
Environmental, 2022b). Seventy-two groups of 75 total harbor seals (3
groups of 2 individuals) were observed during transitional dredging
monitoring in 2022 (61N Environmental, 2022c). Sighting rates of harbor
seals have been highly variable and may have increased since 2005. It
is unknown whether any potential increase was due to local population
increases or habituation to ongoing construction activities. It is
possible that increased sighting rates are correlated with more
intensive monitoring efforts in 2020 and 2021, when the POA used 11
PSOs spread among four monitoring stations.
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 5.
Specific to this action, gray whales and humpback whales are considered
low-frequency (LF) cetaceans, beluga whales and killer whales are
considered mid-frequency (MF) cetaceans, harbor porpoises are
considered high-frequency (HF) cetaceans, Steller sea lions are otariid
pinnipeds, and harbor seals are phocid pinnipeds.
Table 5--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). This division between phocid and otariid pinnipeds is now
reflected in the updated hearing groups proposed in Southall et al.
(2019).
For more detail concerning these groups and associated frequency
ranges,
[[Page 76594]]
please see NMFS (2018) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals 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
are expected to potentially occur from vibratory pile installation and
removal, and impact pile removal. The effects of underwater noise from
the POA's proposed activities have the potential to result in Level B
harassment of marine mammals in the action area and, for some species
as a result of certain activities, Level A harassment.
Background on Sound
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used 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: Erbe and Thomas (2022); Au and Hastings
(2008); Richardson et al. (1995); Urick (1983); as well as the
Discovery of Sound in the Sea website at <a href="https://dosits.org/">https://dosits.org/</a>.
Sound is a vibration that travels as an acoustic wave through a
medium such as a gas, liquid or solid. Sound waves alternately compress
and decompress the medium as the wave travels. In water, sound waves
radiate in a manner similar to ripples on the surface of a pond and may
be either directed in a beam (narrow beam or directional sources) or
sound may radiate in all directions (omnidirectional sources), as is
the case for sound produced by the construction activities considered
here. The compressions and decompressions associated with sound waves
are detected as changes in pressure by marine mammals and human-made
sound receptors such as hydrophones.
Sound travels more efficiently in water than almost any other form
of energy, making the use of sound as a primary sensory modality ideal
for inhabitants of the aquatic environment. In seawater, sound travels
at roughly 1,500 meters per second (m/s). In air, sound waves travel
much more slowly at about 340 m/s. However, the speed of sound in water
can vary by a small amount based on characteristics of the transmission
medium such as temperature and salinity.
The basic characteristics of a sound wave 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 with
distance, except in certain cases in shallower water. The amplitude of
a sound pressure wave is related to the subjective ``loudness'' of a
sound and is typically expressed in decibels (dB), which are a relative
unit of measurement that is used to express the ratio of one value of a
power or pressure to another. A sound pressure level (SPL) in dB is
described as the ratio between a measured pressure and a reference
pressure, 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. For example, a 10-dB increase is a
ten-fold increase in acoustic power. A 20-dB increase is then a 100-
fold increase in power and a 30-dB increase is a 1000-fold increase in
power. However, a ten-fold increase in acoustic power does not mean
that the sound is perceived as being 10 times louder. The dB is a
relative unit comparing two pressures; therefore, a reference pressure
must always be indicated. For underwater sound, this is 1 microPascal
([mu]Pa). For in-air sound, the reference pressure is 20 microPascal
([mu]Pa). The amplitude of a sound can be presented in various ways;
however, NMFS typically considers three metrics: sound exposure level
(SEL), root-mean-square (RMS) SPL, and peak SPL (defined below). The
source level represents the SPL referenced at a standard distance from
the source, typically 1 m (Richardson et al., 1995; American National
Standards Institute (ANSI, 2013), while the received level is the SPL
at the receiver's position. For pile driving activities, the SPL is
typically referenced at 10 m.
SEL (represented as dB referenced to 1 micropascal squared 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 (e.g., single strike or
single shot SEL) is calculated over the time window containing the
entire pulse (i.e., 100 percent of the acoustic energy). SEL can also
be a cumulative metric; it can be accumulated over a single pulse (for
pile driving this is the same as single-strike SEL, above;
SEL<INF>ss</INF>), or calculated over periods containing multiple
pulses (SEL<INF>cum</INF>). Cumulative SEL (SEL<INF>cum</INF>)
represents the total energy accumulated by a receiver over a defined
time window or during an event. The SEL metric is useful because it
allows sound exposures of different durations to be related to one
another in terms of total acoustic energy. The duration of a sound
event and the number of pulses, however, should be specified as there
is no accepted standard duration over which the summation of energy is
measured.
RMS SPL is equal to 10 times the logarithm (base 10) of the ratio
of the mean-square sound pressure to the specified reference value, and
given in units of dB (International Organization for Standardization
(ISO), 2017). 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 SPL. For impulsive sounds, RMS is
calculated by the portion of the waveform containing 90 percent of the
sound energy from the impulsive event (Madsen, 2005).
Peak SPL (also referred to as zero-to-peak sound pressure or 0-pk)
is the maximum instantaneous sound pressure measurable in the water,
which can arise from a positive or negative sound pressure, during a
specified time, for a specific frequency range at a specified distance
from the source, and is represented in the same units as the RMS sound
pressure (ISO, 2017). Along with SEL, this metric is used in evaluating
the potential for permanent
[[Page 76595]]
threshold shift (PTS) and temporary threshold shift (TTS) associated
with impulsive sound sources.
Sounds are also characterized by their temporal components.
Continuous sounds are those whose sound pressure level remains above
that of the ambient or background sound with negligibly small
fluctuations in level (ANSI, 2005) while intermittent sounds are
defined as sounds with interrupted levels of low or no sound (National
Institute for Occupational Safety and Health (NIOSH), 1998). A key
distinction between continuous and intermittent sound sources is that
intermittent sounds have a more regular (predictable) pattern of bursts
of sounds and silent periods (i.e., duty cycle), which continuous
sounds do not.
Sounds may be either impulsive or non-impulsive (defined below).
The distinction between these two sound types is important because they
have differing potential to cause physical effects, particularly with
regard to noise-induced hearing loss (e.g., Ward, 1997 in Southall et
al., 2007). Please see NMFS (2018) and Southall et al. (2007, 2019) for
an in-depth discussion of these concepts.
Impulsive sound sources (e.g., explosions, gunshots, sonic booms,
seismic airgun shots, impact pile driving) produce signals that are
brief (typically considered to be less than 1 second), broadband,
atonal transients (ANSI, 1986, 2005; NIOSH, 1998) and occur either as
isolated events or repeated in some succession. Impulsive sounds are
all characterized by a relatively rapid rise from ambient pressure to a
maximal pressure value followed by a rapid decay period that may
include a period of diminishing, oscillating maximal and minimal
pressures, and generally have an increased capacity to induce physical
injury as compared with sounds that lack these features. Impulsive
sounds are intermittent in nature. The duration of such sounds, as
received at a distance, can be greatly extended in a highly reverberant
environment.
Non-impulsive sounds can be tonal, narrowband, or broadband, brief
or prolonged, and may be either continuous or non-continuous (ANSI,
1995; NIOSH, 1998). Some of these non-impulsive sounds can be transient
signals of short duration but without the essential properties of
impulses (e.g., rapid rise time). Examples of non-impulsive sounds
include those produced by vessels, aircraft, machinery operations such
as drilling or dredging, vibratory pile driving, and active sonar
systems.
Even in the absence of sound from the specified activity, the
underwater environment is characterized by sounds from both natural and
anthropogenic sound sources. Ambient sound is defined as a composite of
naturally-occurring (i.e., non-anthropogenic) sound from many sources
both near and far (ANSI, 1995). Background sound is similar, but
includes all sounds, including anthropogenic sounds, minus the sound
produced by the proposed activities (NMFS, 2012, 2016a). 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 background and
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, background and 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 background and
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 background 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 background sound
for frequencies between 20 and 300 Hz. In general, the frequencies of
many anthropogenic sounds, particularly those produced by construction
activities, are below 1 kHz (Richardson et al., 1995). When sounds at
frequencies greater than 1 kHz are produced, they generally attenuate
relatively rapidly (Richardson et al., 1995), particularly above 20 kHz
due to propagation losses and absorption (Urick, 1983).
Transmission loss (TL) defines the degree to which underwater sound
has spread in space and lost energy after having moved through the
environment and reached a receiver. It is defined by the ISO as the
reduction in a specified level between two specified points that are
within an underwater acoustic field (ISO, 2017). Careful consideration
of transmission loss and appropriate propagation modeling is a crucial
step in determining the impacts of underwater sound, as it helps to
define the ranges (isopleths) to which impacts are expected and depends
significantly on local environmental parameters such as seabed type,
water depth (bathymetry), and the local speed of sound. Geometric
spreading laws are powerful tools which provide a simple means of
estimating TL, based on the shape of the sound wave front in the water
column. For a sound source that is equally loud in all directions and
in deep water, the sound field takes the form of a sphere, as the sound
extends in every direction uniformly. In this case, the intensity of
the sound is spread across the surface of the sphere, and thus we can
relate intensity loss to the square of the range (as area = 4*pi*r\2\).
When expressing logarithmically in dB as TL, we find that TL =
20*Log<INF>10</INF>(range), this situation is known as spherical
spreading. In shallow water, the sea surface and seafloor will bound
the shape of the sound, leading to a more cylindrical shape, as the top
and bottom of the sphere is truncated by the largely reflective
boundaries. This situation is termed cylindrical spreading, and is
given by TL = 10*Log<INF>10</INF>(range) (Urick, 1983). An intermediate
scenario may be defined by the equation TL =
15*Log<INF>10</INF>(range), and is referred to as practical spreading.
Though these geometric spreading laws do not capture many often
important details (scattering, absorption, etc.), they offer a
reasonable and simple approximation of how sound decreases in intensity
as it is transmitted. In the absence of measured data indicating the
level of transmission loss at a given site for a specific activity,
NMFS recommends practical spreading (i.e., 15*Log<INF>10</INF>(range))
to model acoustic propagation for construction activities in most
nearshore environments.
The sum of the various natural and anthropogenic sound sources at
any given location and time depends not only on the source levels, but
also on the propagation of sound through the environment. 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, background and 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
[[Page 76596]]
can vary by 10 to 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.
Background underwater noise levels in the NES1 Project area are
both variable and relatively high, primarily because of extreme tidal
activity, elevated sediment loads in the water column, periodic high
winds, the seasonal presence of ice, and anthropogenic activities.
Sources of anthropogenic noise in the NES1 Project area consist of
dredging operations, boats, ships, oil and gas operations, construction
noise, and aircraft overflights from JBER and Ted Stevens International
Airport, all of which contribute to high underwater noise levels in
upper Cook Inlet (e.g., Blackwell and Greene, 2002; (Knik Arm Bridge
and Toll Authority (KABATA), 2011). The lower range of broadband (10 to
10,000 Hz) background sound levels obtained during underwater
measurements at Port MacKenzie, located across Knik Arm from the POA,
ranged from 115 to 133 dB re 1 [mu]Pa RMS (Blackwell, 2005). Background
sound levels measured during the 2007 test pile study for the POA's
Marine Terminal Redevelopment Project (MTRP) site ranged from 105 to
135 dB (URS Corporation, 2007). The background SPLs obtained in that
study were highly variable, with most SPL recordings exceeding 120 dB
RMS. Background sound levels measured in 2008 at the MTRP site ranged
from 120 to 150 dB RMS (Scientific Fishery Systems, Inc., 2009). These
measurements included industrial sounds from maritime operations, but
ongoing USACE maintenance dredging and pile driving from construction
were not underway at the time of the study.
Background sound levels were measured at the POA during the PAMP
2016 Test Pile Program (TPP) in the absence of pile driving at two
locations during a 3[hyphen]day break in pile installation. Median
background noise levels, measured at a location just offshore of the
POA SFD and at a second location about 1 km offshore, were 117 and
122.2 dB RMS, respectively (Austin et al., 2016). NMFS considers the
median sound levels to be most appropriate when considering background
noise levels for purposes of evaluating the potential impacts of the
proposed project on marine mammals (NMFS, 2012). By using the median
value, which is the 50th percentile of the measurements, for background
noise levels, one will be able to eliminate the few transient loud
identifiable events that do not represent the true ambient condition of
the area. This is relevant because during 2 of the 4 days (50 percent)
when background measurement data were being collected, the USACE was
dredging Terminal 3 (located just north of the Ambient-Offshore
hydrophone) for 24 hours per day with two 1-hour breaks for crew
change. On the last 2 days of data collection, no dredging was
occurring. Therefore, the median provides a better representation of
background noise levels when the NES1 project would be occurring.
During the measurements, some typical sound signals were noted, such as
noise from current flow and the passage of vessels.
With regard to spatial considerations of the measurements, the
offshore location is most applicable to assessing background sound
during the NES1 Project (NMFS, 2012). The median background noise level
measured at the offshore hydrophone was 122.2 dB RMS. The measurement
location closer to the POA was quieter, with a median of 117 dB;
however, that hydrophone was placed very close to a dock. During PCT
acoustic monitoring, noise levels in Knik Arm absent pile driving were
also collected (Illingworth & Rodkin (I&R), 2021a, 2022b)); however,
the PCT IHAs did not require background noise measurements to be
collected. These measurements were not collected in accordance to NMFS
(2012) guidance for measuring background noise and thus cannot be used
here for that purpose. Despite this, the noise levels measured during
the PCT project were not significantly different from 122.2 dB (I&R,
2021a, 2022b). If additional background data are collected in the
future in this region, NMFS may re-evaluate the data to appropriately
characterize background sound levels in Knik Arm.
Description of Sound Sources for the Specified Activities
In-water construction activities associated with the project that
have the potential to incidentally take marine mammals through exposure
to sound would include impact sheet pile removal, vibratory pile
installation and removal, and pile splitting (assumed to be similar to
vibratory pile installation and removal). Impact hammers typically
operate by repeatedly dropping and/or pushing a heavy piston onto a
pile to drive the pile into the substrate. For the NES1 project, a
small number of strikes from an impact hammer may be used to loosen
sheet piles for removal. Sound generated by impact hammers is
impulsive, 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
typically produce less sound (i.e., lower levels) 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; California Department of Transportation
(CALTRANS), 2015, 2020). Sounds produced by vibratory hammers are non-
impulsive; the rise time is slower, reducing the probability and
severity of injury, and the 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 POA's 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 NES1 project site,
visual and other non-acoustic stressors would be limited, and any
impacts to marine mammals are expected to primarily be acoustic in
nature.
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic
environment from pile driving is the primary means by which marine
mammals may be harassed from the POA's specified activity. In general,
animals exposed to natural or anthropogenic sound may experience
physical and psychological effects, ranging in magnitude from none to
severe (Southall et al., 2007, 2019). 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 as 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
[[Page 76597]]
exposure, the distance between the pile and the animal, received
levels, behavior at time of exposure, and previous history with
exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss
physical auditory effects (threshold shifts) followed by behavioral
effects and potential impacts on habitat.
NMFS defines a noise-induced threshold shift (TS) as a change,
usually an increase, in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS, 2018). The amount of
threshold shift is customarily expressed in dB. A TS can be permanent
or temporary. As described in NMFS (2018) there are numerous factors to
consider when examining the consequence of TS, including, but not
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough
duration or to a high enough level to induce a TS, the magnitude of the
TS, time to recovery (seconds to minutes or hours to days), the
frequency range of the exposure (i.e., spectral content), the hearing
frequency range of the exposed species relative to the signal's
frequency spectrum (i.e., how animal uses sound within the frequency
band of the signal; e.g., Kastelein et al., 2014), and the overlap
between the animal and the source (e.g., spatial, temporal, and
spectral).
Permanent Threshold Shift (PTS). NMFS defines PTS as a permanent,
irreversible increase in the threshold of audibility at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS, 2018). PTS does not
generally affect more than a limited frequency range, and an animal
that has incurred PTS has incurred some level of hearing loss at the
relevant frequencies; typically animals with PTS are not functionally
deaf (Au and Hastings, 2008; Finneran, 2016). Available data from
humans and other terrestrial mammals indicate that a 40-dB threshold
shift approximates PTS onset (see Ward et al., 1958, 1959, 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 marine mammal TTS measurements
(see Southall et al., 2007, 2019), 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 (Finneran et
al., 2000, 2002; Schlundt et al., 2000). As described in Finneran
(2015), marine mammal studies have shown the amount of TTS increases
with SEL<INF>cum</INF> in an accelerating fashion: at low exposures
with lower SEL<INF>cum</INF>, the amount of TTS is typically small and
the growth curves have shallow slopes. At exposures with higher
SEL<INF>cum</INF>, 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.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). 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. For
cetaceans, published data on the onset of TTS are limited to captive
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise,
and Yangtze finless porpoise (Neophocoena asiaeorientalis) (Southall et
al., 2019). For pinnipeds in water, measurements of TTS are limited to
harbor seals, elephant seals (Mirounga angustirostris), bearded seals
(Erignathus barbatus) and California sea lions (Zalophus californianus)
(Kastak et al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021,
2022a, 2022b; Reichmuth et al., 2019; Sills et al., 2020). TTS was not
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals
exposed to single airgun impulse sounds at levels matching previous
predictions of TTS onset (Reichmuth et al., 2016). These studies
examine hearing thresholds measured in marine mammals before and after
exposure to intense or long-duration sound exposures. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor
seals and harbor porpoises have a lower TTS onset than other measured
pinniped or cetacean species (Finneran, 2015). In addition, TTS can
accumulate across multiple exposures, but the resulting TTS will be
less than the TTS from a single, continuous exposure with the same SEL
(Mooney et al., 2009; Finneran et al., 2010; Kastelein et al., 2014,
2015). This means that TTS predictions based on the total, cumulative
SEL will overestimate the amount of TTS from intermittent exposures,
such as sonars and impulsive sources. Nachtigall et al. (2018) describe
measurements of hearing sensitivity of multiple odontocete species
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale
(Pseudorca crassidens)) when a relatively loud sound was preceded by
[[Page 76598]]
a warning sound. These captive animals were shown to reduce hearing
sensitivity when warned of an impending intense sound. Based on these
experimental observations of captive animals, the authors suggest that
wild animals may dampen their hearing during prolonged exposures or if
conditioned to anticipate intense sounds. Another study showed that
echolocating animals (including odontocetes) might have anatomical
specializations that might allow for conditioned hearing reduction and
filtering of low-frequency ambient noise, including increased stiffness
and control of middle ear structures and placement of inner ear
structures (Ketten et al., 2021). Data available on noise-induced
hearing loss for mysticetes are currently lacking (NMFS, 2018).
Additionally, the existing marine mammal TTS data come from a limited
number of individuals within these species.
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 that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulsive 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, 2019). 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.
Behavioral Harassment. Exposure to noise also has the potential to
behaviorally disturb marine mammals to a level that rises to the
definition of harassment under the MMPA. Generally speaking, NMFS
considers a behavioral disturbance that rises to the level of
harassment under the MMPA a non-minor response--in other words, not
every response qualifies as behavioral disturbance, and for responses
that do, those of a higher level, or accrued across a longer duration,
have the potential to affect foraging, reproduction, or survival.
Behavioral disturbance may include a variety of effects, including
subtle changes in behavior (e.g., minor or brief avoidance 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. Behavioral responses may include 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., 2004; Southall et al.,
2007, 2019; 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., 2004). 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; Wartzok et al., 2004; National Research Council (NRC), 2005).
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 (e.g.,
seismic airguns) have been varied but often consist of avoidance
behavior or other behavioral changes (Richardson et al., 1995; Morton
and Symonds, 2002; 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, 2013b). 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.
[[Page 76599]]
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). For example, harbor porpoise' respiration rate increased in
response to pile driving sounds at and above a received broadband SPL
of 136 dB (zero-peak SPL: 151 dB re 1 [mu]Pa; SEL of a single strike:
127 dB re 1 [mu]Pa\2\-s) (Kastelein et al., 2013).
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) or vocalizations (Foote et al., 2004),
respectively, while North Atlantic 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).
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 (England et al., 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 fishes 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 5-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 1 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 (i.e., meaningful) 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.
Behavioral Reactions Observed at the POA. Specific to recent
construction at the POA, behavioral reactions to pile driving have not
been reported in non-CIBW species. During POA's PCT construction, 81
harbor seals were observed within estimated Level B harassment zones
associated with vibratory and impact installation and or removal of 36-
inch (61-cm) and 144-inch (366-cm) piles, and five harbor seals were
observed within estimated Level A harassment zones during the
installation of 144-inch (366-cm) piles. No observable behavioral
reactions were observed in any of these seals (61N Environmental, 2021,
2022a). One harbor porpoise was observed within the estimated Level B
harassment zone during vibratory driving of a 36-inch (61-cm) pile in
May 2021. The animal was travelling at a moderate pace. No observable
reactions to pile driving were noted by the PSOs. Another harbor
porpoise may have been within the
[[Page 76600]]
estimated Level B harassment zone during the impact installation of 36-
inch (61-cm) piles in June 2021, but PSOs did not record any behavioral
responses of this individual to the pile driving activities. Similarly
13 harbor seals observed within estimated Level B harassment zones
associated with pile driving 36-inch (61-cm) piles during POA's SFD
construction did not exhibit observable behavioral reactions (61N
Environmental, 2022b).
Specific to CIBWs, several years of marine mammal monitoring data
demonstrate the behavioral responses to pile driving at the POA.
Previous pile driving activities at the POA include the installation
and removal of sheet piles, the vibratory and impact installation of
24-inch (61-cm), 36-inch (91-cm), 48-in (122-cm), and 144-inch (366-cm)
pipe piles, and the vibratory installation of 72-inch (183-cm) air
bubble casings.
Kendall and Cornick (2015) provide a comprehensive overview of 4
years of scientific marine mammal monitoring conducted before (2005-
2006) and during the POA's MTR Project P (2008-2009). These were
observations made by PSOs independent of the POA and their pile driving
activities (i.e., not construction based PSOs). The authors
investigated CIBW behavior before and during pile driving activity at
the POA. Sighting rates, mean sighting duration, behavior, mean group
size, group composition, and group formation were compared between the
two periods. A total of about 2,329 hours of sampling effort was
completed across 349 days from 2005 to 2009. Overall, 687 whales in 177
groups were documented during the 69 days that whales were sighted. A
total of 353 and 1,663 hours of pile driving took place in 2008 and
2009, respectively. There was no relationship between monthly CIBW
sighting rates and monthly pile driving rates (r = 0.19, p = 0.37).
Sighting rates before (n = 12; 0.06 <plus-minus> 0.01) and during (n =
13; 0.01 <plus-minus> 0.03) pile driving were not significantly
different. However, sighting duration of CIBWs decreased significantly
during pile driving (39 <plus-minus> 6 min before and 18 <plus-minus> 3
min during). There were also significant differences in behavior before
versus during pile driving. CIBWs primarily traveled through the study
area both before and during pile driving; however, traveling increased
relative to other behaviors during pile driving. Documentation of
milling was observed on 21 occasions during pile driving. Mean group
size decreased during pile driving; however, this difference was not
statistically significant. In addition, group composition was
significantly different before and during pile driving, with more white
(i.e., likely older) animals being present during pile driving (Kendall
and Cornick, 2015). CIBWs were primarily observed densely packed before
and during pile driving; however, the number of densely packed groups
increased by approximately 67 percent during pile driving. There were
also significant increases in the number of dispersed groups
(approximately 81 percent) and lone white whales (approximately 60
percent) present during pile driving than before pile driving (Kendall
and Cornick, 2015).
During PCT and SFD construction monitoring, behaviors of CIBWs
groups were compared by month and by construction activity (61N
Environmental, 2021, 2022a, 2022b). Little variability was evident in
the behaviors recorded from month to month, or between sightings that
coincided with in-water pile installation and removal and those that
did not (61N Environmental, 2021, 2022a). Definitive behavioral
reactions to in-water pile driving or avoidance behaviors were not
documented; however, potential reactions (where a group reversed its
trajectory shortly after the start of in-water pile driving occurred; a
group reversed its trajectory as it got closer to the sound source
during active in-water pile driving; or upon an initial sighting, a
group was already moving away from in-water pile driving, raising the
possibility that it had been moving towards, but was only sighted after
they turned away) and instances where CIBWs moved toward active in-
water pile driving were recorded. During these instances, impact
driving appeared to cause potential behavioral reactions more readily
than vibratory hammering (61N Environmental, 2021, 2022a, 2022b). One
minor difference documented during PCT construction was a slightly
higher incidence of milling behavior and diving during the periods of
no pile driving and slightly higher rates of traveling behavior during
periods when potential CIBW behavioral reactions to pile driving, as
described above, were recorded (61N Environmental, 2021, 2022a). Note,
narratives of each CIBW reaction can be found in the appendices of the
POA's final monitoring reports (61N Environmental, 2021, 2022a, 2022b).
Acoustically, Saxon-Kendall et al. (2013) recorded echolocation
clicks (which can be indicative of feeding behavior) during the MTR
Project at the POA both while pile driving was occurring and when it
was not. This indicates that while feeding is not a predominant
behavior observed in CIBWs sighted near the POA (61N Environmental,
2021, 2022a, 2022b, 2022c; Easley-Appleyard and Leonard, 2022) CIBWs
can and still exhibit feeding behaviors during pile driving activities.
In addition, Castellote et al. (2020) found low echolocation detection
rates in lower Knik Arm (i.e., Six Mile, Port MacKenzie, and Cairn
Point) and suggested that CIBWs moved through that area relatively
quickly when entering or exiting the Arm. No whistles or noisy
vocalizations were recorded during the MTR construction activities;
however, it is possible that persistent noise associated with
construction activity at the MTR project masked beluga vocalizations
and or that CIBWs did not use these communicative signals when they
were near the MTR Project (Saxon-Kendall et al., 2013).
Recently, McHuron et al. (2023) developed a model to predict
general patterns related to the movement and foraging decisions of
pregnant CIBWs in Cook Inlet. They found that the effects of
disturbance from human activities, such as pile driving activities
occurring at the POA assuming no prescribed mitigation measures
implemented, are inextricably linked with prey availability. If prey
are abundant during the summer and early fall, and prey during winter
is above some critical threshold, pregnant CIBWs can likely cope with
intermittent disruptions, such as those produced by pile driving at the
POA (McHuron et al., 2023). However, they stress that more information
needs to be acquired regarding CIBW prey and CIBW body condition,
specifically in their critical habitat, to better understand possible
behavioral responses to disturbance.
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., Selye, 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
[[Page 76601]]
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, 2005), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar construction projects.
Norman (2011) reviewed environmental and anthropogenic stressors
for CIBWs. Lyamin et al. (2011) determined that the heart rate of a
beluga whale increases in response to noise, depending on the frequency
and intensity. Acceleration of heart rate in the beluga whale is the
first component of the ``acoustic startle response.'' Romano et al.
(2004) demonstrated that captive beluga whales exposed to high-level
impulsive sounds (i.e., seismic airgun and/or single pure tones up to
201 dB RMS) resembling sonar pings showed increased stress hormone
levels of norepinephrine, epinephrine, and dopamine when TTS was
reached. Thomas et al. (1990) exposed beluga whales to playbacks of an
oil-drilling platform in operation (``Sedco 708,'' 40 Hz-20 kHz; source
level 153 dB). Ambient SPL at ambient conditions in the pool before
playbacks was 106 dB and 134 to 137 dB RMS during playbacks at the
monitoring hydrophone across the pool. All cell and platelet counts and
21 different blood chemicals, including epinephrine and norepinephrine,
were within normal limits throughout baseline and playback periods, and
stress response hormone levels did not increase immediately after
playbacks. The difference between the Romano et al. (2004) and Thomas
et al. (1990) studies could be the differences in the type of sound
(seismic airgun and/or tone versus oil drilling), the intensity and
duration of the sound, the individual's response, and the surrounding
circumstances of the individual's environment. The construction sounds
in the Thomas et al. (1990) study would be more similar to those of
pile installation than those in the study investigating stress response
to water guns and pure tones. Therefore, no more than short-term, low-
hormone stress responses, if any, of beluga whales or other marine
mammals are expected as a result of exposure to in-water pile
installation and removal during the NES1 project.
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 receiving 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 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 (Hotchkin and
Parks, 2013).
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 human-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 (though not necessarily one
that would be associated with harassment).
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, 2010; 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 (Hotchkin and Parks, 2013). Masking can be
tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled
[[Page 76602]]
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 at or near the proposed NES1 project site may be
exposed to anthropogenic noise which may be 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). For example, in response to loud noise, beluga whales may
shift the frequency of their echolocation clicks to prevent masking by
anthropogenic noise (Tyack, 2000; Eickmeier and Vallarta, 2022).
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources such as vibratory pile driving.
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
construction during the POA's 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 the
fitness of individual marine mammals would be impacted.
Airborne Acoustic Effects. Pinnipeds that occur near the project
site could be exposed to airborne sounds associated with construction
activities 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
airborne acoustic harassment criteria. Although pinnipeds are known to
haul-out regularly on man-made objects, we believe that incidents of
take resulting solely from airborne sound are unlikely given there are
no known pinniped haulout or pupping sites within the vicinity of the
proposed project area; the nearest known pinniped haulout is located a
minimum of 24 km south-southwest of Anchorage for harbor seals.
Cetaceans are not expected to be exposed to airborne sounds that would
result in harassment as defined under the MMPA.
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.
Potential Effects on Marine Mammal Habitat
The proposed project will occur within the same footprint as
existing marine infrastructure. The nearshore and intertidal habitat
where the proposed project will occur is an area of relatively high
marine vessel traffic. Temporary, intermittent, and short-term habitat
alteration may result from increased noise levels during the proposed
construction activities. Effects on prey species will be limited in
time and space.
Removal of the North Extension bulkhead and impounded fill would
result in restoration of subtidal and intertidal habitats that were
lost when that structure was constructed in 2005-2011. Removal of
approximately 1.35 million CY of fill material from below the high tide
line would re-create approximately 0.05 km\2\ (13 acres) of intertidal
and subtidal habitat, returning them to their approximate original
slope and shoreline configuration. The proposed project area is not
considered to be high-quality habitat for marine mammals or marine
mammal prey, such as fish, and it is anticipated that the removal of
the North Extension bulkhead would increase the amount of available
habitat for both marine mammals and fish because they would be able to
swim through the area at higher water levels. The area is expected to
be of higher quality to marine mammals and fish as it returns to its
natural state and is colonized by marine organisms.
Water quality--Temporary and localized reduction in water quality
would occur as a result of in-water construction activities. Most of
this effect would occur during the installation and removal of piles
when bottom sediments are disturbed. The installation and removal of
piles would disturb bottom sediments and may cause a temporary increase
in suspended sediment in the project area. During pile removal,
sediment attached to the pile moves vertically through the water column
until gravitational forces cause it to slough off under its own weight.
The small resulting sediment plume is expected to settle out of the
water column within a few hours. Studies of the effects of turbid water
on fish (marine mammal prey) suggest that concentrations of suspended
sediment can reach thousands of milligrams per liter before an acute
toxic reaction is expected (Burton, 1993).
Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Since the currents are so strong in the
area, following the completion of sediment-disturbing activities,
suspended sediments in the water column should dissipate and quickly
return to background levels in all construction scenarios. Turbidity
within the water column has the potential to reduce the level of oxygen
in the water and irritate the gills of prey fish species in the
proposed project area. However, turbidity plumes associated with the
project would be temporary and localized, and fish in the proposed
project area would be able to move away from and avoid the areas where
plumes may occur. Therefore, it is expected that the impacts on prey
fish species from turbidity, and therefore on marine mammals, would be
minimal and temporary. In general, the area likely impacted by the
proposed construction activities is relatively small compared to the
available marine mammal habitat in Knik Arm.
Potential Effects on Prey. Sound may affect marine mammals through
impacts on the abundance, behavior, or distribution of prey species
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal
prey varies by species, season, and location and, for some, is not well
documented. Studies regarding the effects of noise on known marine
mammal prey are described here.
Fishes 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 et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear
[[Page 76603]]
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
fishes (e.g. Scholik and Yan, 2001, 2002; Popper and Hastings, 2009).
Several studies have demonstrated that impulsive 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., Pe[ntilde]a et
al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et
al., 2012). More commonly, though, the impacts of noise on fishes are
temporary.
During the POA's MTRP, the effects of impact and vibratory
installation of 30-inch (76-cm) steel sheet piles at the POA on 133
caged juvenile coho salmon in Knik Arm were studied (Hart Crowser
Incorporated et al., 2009; Houghton et al., 2010). Acute or delayed
mortalities, or behavioral abnormalities were not observed in any of
the coho salmon. Furthermore, results indicated that the pile driving
had no adverse effect on feeding ability or the ability of the fish to
respond normally to threatening stimuli (Hart Crowser Incorporated et
al., 2009; Houghton et al., 2010).
SPLs of sufficient strength have been known to cause injury to
fishes 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. (2012b) showed that a TTS of
4 to 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.,
2012a; Casper et al., 2013, 2017).
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from pile
installation and removal. The frequency range in which fishes generally
perceive underwater sounds is 50 to 2,000
[…truncated; see source link]Indexed from Federal Register on November 6, 2023.
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