# Taking of Marine Mammals Incidental to Specific Activities; Taking of Marine Mammals Incidental to Pile Driving and Removal Activities During Construction of the Hoonah Marine Industrial Center Cargo Dock Project, Hoonah, Alaska

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2021-04431

## Record

- **Collection:** Federal Register
- **Document type:** Notice
- **Published:** March 4, 2021
- **Citation:** 86 FR 12630

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RIN 0648-XA858]
Taking of Marine Mammals Incidental to Specific Activities; Taking of Marine Mammals Incidental to Pile Driving and Removal Activities During Construction of the Hoonah Marine Industrial Center Cargo Dock Project, Hoonah, 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.

SUMMARY:

NMFS has received a request from the City of Hoonah (City) for authorization to take marine mammals incidental to pile driving and removal activities during construction upgrades of a cargo dock at the city-owned Hoonah Marine Industrial Center (HMIC) in Port Frederick Inlet on Chichagof Island in Hoonah, 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-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorizations and agency responses will be summarized in the final notice of our decision.

DATES:

Comments and information must be received no later than April 5, 2021.

ADDRESSES:

Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service and should be sent by electronic mail to
ITP.Egger@noaa.gov.

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 must not exceed a 25-megabyte file size, including all attachments. All comments received are a part of the public record and will generally be posted online at

https://

www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act

without change. All personal identifying information (
e.g.,
name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT:

Stephanie Egger, Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at:
https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
In case of problems accessing these documents, or for anyone who is unable to comment via electronic mail, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.
) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed incidental take authorization may be provided to the public for review.

Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such 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 such takings are set forth. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below.

National Environmental Policy Act

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

We will review all comments submitted in response to this notice prior to concluding our NEPA process or making a final decision on the IHA request.

Summary of Request

On October 28, 2020 NMFS received a request from the City for an IHA to take marine mammals incidental to pile driving and removal during construction upgrades of a cargo dock at the HMIC in Port Frederick Inlet on Chichagof Island in Hoonah, Alaska. The application was deemed adequate and complete on February 2, 2021. The applicant's request is for take of nine species of marine mammals by Level B harassment and five species by Level A harassment. Neither the City nor NMFS expects serious injury or mortality to result from this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

The purpose of this project is to make upgrades to the HMIC. Upgrades to the site include the installation of three breasting dolphins, a sheet pile bulk cargo dock, fender piles, and a catwalk. The proposed upgrades are needed to continue safely accommodating barges and other vessels delivering essential goods to the City.

The City is only accessible by air and water. Small amounts of cargo are transported into the community by plane; however, the majority is delivered weekly by barges from April through September (AML 2020). When weather permits, front load barges utilize a gravel landing located next to the existing City dock. The gravel landing provides a makeshift location to unload heavy cargo using a ramp and forklifts. During winter months, inclement weather events, and for more frequent deliveries, locals utilizes the Alaska Marine Highway System (AMHS) ferries and the local ferry terminal.

The existing gravel landing at HMIC was not originally designed for barges and requires an additional ramp and favorable weather conditions to safely unload cargo. Even during favorable weather, the space and depth places the barges and crew at risk, and the landing cannot safely accommodate the fleet of barges delivering to Hoonah. With the decrease in AMHS ferry service (due to State funding cuts) it is imperative that a reliable way to receive goods in the City is available.

The HMIC cargo dock is one component of the HMIC, which is a phased approach to enhance the Hoonah waterfront and to provide infrastructure to support the cruise ship industry and various other maritime industries (see Figure 4 of the application). The purpose of HMIC cargo dock project is to make improvements to the existing gravel landing to enable barges to land during all conditions. The project is needed because the existing facility cannot provide consistent and safe berthing for barges. Once the project is completed, the City will be able to reliably receive goods year-round and in all weather conditions. Currently, Alaska Marine Line barges offers seasonal ramp barge service into the City; however, this project will allow for year-round, weekly deliveries by ocean going barges.

Dates and Duration

The applicant is requesting an IHA to conduct pile driving and removal over 110 working days (not necessarily consecutive) beginning in spring and extending through the summer of 2021 as needed. Approximately 50 days of vibratory and 28 days of impact hammering will occur. An additional 35 days of drilling/down-the-hole (DTH) will occur to stabilize the piles. These are discussed in further detail below. The total construction duration accounts for the time required to mobilize materials and resources and construct the project. The duration also accounts for potential delays in material deliveries, equipment maintenance, inclement weather, and shutdowns that may occur to prevent impacts to marine mammals.

Specific Geographic Region

The proposed project at the HMIC is located in Port Frederick Inlet, approximately 0.8 kilometers (km) (0.5 miles) northwest of downtown Hoonah 0.24 km (0.15 miles) east of the State of Alaska Ferry Terminal in Southeast Alaska; T43S, R61E, S20, Copper River Meridian, USGS Quadrangle Juneau A5 NE; latitude 58.11549 and longitude −135.4547 (see Figure 1 below and see also Figure 1, 2, 3, and Appendix A, Sheet 1 of the application).

Port Frederick is a 24-km inlet that dips into northeast Chichagof Island from Icy Strait, leading to Neka Bay and Salt Lake Bay. The inlet varies between 4 and almost 6 km wide with a depth of up to 150 meters (m) (see Figure 6 of the application). Near the proposed project, the inlet is 12 to 28 m deep (NOAA 2018). NMFS's ShoreZone Mapper details the proposed project site as a semi-protected/partially mobile/sediment or rock and sediment habitat class with gravel beaches environmental sensitivity index (NMFS 2020).

EN04MR21.004

Detailed Description of Specific Activity

The project would involve installing breasting dolphins, a solid fill sheet pile dock, and fender.

Construction of the three breasting dolphins would include:

Installation of 10 temporary 30-inch (in) diameter steel piles as templates to guide proper installation of permanent piles (these piles would be removed prior to project completion); and

Installation of 9 permanent 36-in diameter steel piles

○ Breasting Dolphin 1—(1) vertical 36-in steel pile and (2) 36-in batter steel piles

○ Breasting Dolphin 2—(1) vertical 36-in steel pile and (2) 36-in batter steel pile

○ Breasting Dolphin 3—(1) vertical 36-in steel pile and (2) 36-in batter steel pile

Construction of the bulk cargo dock would include (see Figure 4; Appendix A: Sheets 3-4 of the application):

Installation of 20 temporary 30-in steel piles as templates to guide proper installation of permanent H-piles (these piles would be removed prior to project completion);

Installation of 12 permanent H-piles to guide proper installation of sheets;

Installation of 500 permanent sheet piles (130 linear feet); and

Filling the area within sheet piles with 9,600 cubic yards of fill

Installation of the fender piles would include (see Figure 4; Appendix A: Sheet 3 of the application):

Installation of 20 temporary 30-in steel piles as templates to guide proper installation of permanent fender piles (these piles would be removed prior to project completion); and

Installation of 6 permanent 20-in fender piles in front of sheet pile cargo dock

Construction Sequence

In-water construction of the HMIC cargo dock components is expected to occur via the following sequence:

(1) Vibrate twenty 30-in temporary piles to use as a guide to install H-piles for the cargo dock.

(2) Vibrate and impact 12 H-piles to depth to hold the sheets into place.

(3) Remove the temporary piles.

(4) Using the H-piles as a guide, vibrate and impact 500 sheets into place to create a barrier prior to placing fill.

(5) Using an excavator place 9,600 cubic yards of fill within the newly constructed cargo dock frame.

After the completion of the cargo dock, the barge will move over to install the six fender piles at the existing city dock face using the following sequence:

(1) Vibrate 20 temporary 30-in piles a minimum of ten feet into bedrock to create a template to guide installation of the permanent piles.

(2) Weld a frame around the temporary piles.

(3) Within the frame: Vibrate, impact, and socket six permanent 20-in fender piles into place.

(4) Remove the frame and temporary piles.

(5) Perform this sequence at the other six fender pile locations.

The three breasting dolphins will be constructed as the barge moves off shore and will install temporary and permanent piles as follows:

(1) Vibrate 10 temporary 30-in piles a minimum of ten feet into bedrock to

create a template to guide installation of the permanent piles.

(2) Weld a frame around the temporary piles.

(3) Within the frame: Vibrate, impact, and socket one vertical and two batter 36-in pile into place.

(4) Remove the frame and temporary piles.

(5) Perform this sequence at the second and third location working farther from the shoreline.

Please see Table 1 below for the specific amount of time required to install and remove piles.

Installation and Removal of Temporary (Template) Piles

Temporary 30-in steel piles would be installed and removed using a vibratory hammer (Table 1).

Installation of Permanent Piles

The permanent H-piles, 20-in, and 36-in piles would be installed through sand and gravel with a vibratory hammer until advancement stops. Then, the pile will be driven to depth with an impact hammer. If design tip elevation is still not achieved, the contractor will utilize a drill to secure the pile. (Note: This DTH method can also be referred to as DTH drilling. It is referred to as DTH throughout this document.) Pile depths are expected to be approximately 40 to 70 feet (ft) below the mudline and estimated to take approximately 1.25-10.5 hours (hrs) per pile to complete.

The permanent sheets would be installed using a vibratory hammer and impact hammer following the same criteria as above to achieve design tip elevation (Table 1). It is expected that it will take around 20 minutes to install each sheet.

Table 1—Pile Driving and Removal Activities

Project component

Temporary pile
installation

Temporary pile
removal

Permanent pile installation

Vibratory Hammer

Diameter of Steel Pile (inches)
30
30
36
H-piles
Sheets
20.

# of Piles
50
50
9
12
500 (130lf)
6.

Max # Piles Vibrated per Day
4
4
4
4
30 sheets
3.

Vibratory Time per Pile (min)
15
15
15
15
15
15.

Vibratory Time per Day (min)
60
60
60
60
450 (7.5 hr)
45.

Number of Days
12.5
12.5
2.25
3
17
2.

Vibratory Time Total
12 hrs 30 mins
12 hrs 30 mins
2 hr 15 mins
3 hrs
292 hrs
1 hr 30 min.

Impact Hammer

Diameter of Steel Pile (inches)

36
H-piles
Sheets
20.

# of Piles

9
12
500 (130lf)
6.

Max # Piles Impacted per Day

2
5
5 sheets
2.

Impact Time per Pile (min)

15
5
5
5.

Impact Time per Day (min)

30
20
25
10.

Number of Days

4.5 day
3
17 days
3.

Impact Time Total

2 hr 15 mins
1 hr
1 hr 30 mins
30 min.

Drilling/DTH

Diameter of Steel Pile (inches)

36
H-Piles

20.

Total Quantity

9
12

6.

Anchor Diameter

33
20

20.

Max # Piles Anchored per Day

2
2

2.

Time per Pile

5-10 hrs
3-4 hrs

1 hr.

Actual Time Spent Driving per Pile

60 min
60 min

60 min.

Time per Day

12 hrs (max)
12 hrs (max)

12 hrs (max).

Actual Time Spent Driving per Day

72 mins (1 hr 12 mins; max)
2 hrs (max)

1 hr (max).

Blows per Pile

27,000-54,000
20,000

15,000.

Number of Days

15 days
17 days

3 days.

Drilling Total Time

45-90 hours
20 hours

4 hours.

In addition to the activities described above, the proposed action will involve other in-water construction and heavy machinery activities. Other types of in-water work including with heavy machinery will occur using standard barges, tug boats, and positioning piles on the substrate via a crane (
i.e.,
“stabbing the pile”). Workers will be transported from shore to the barge work platform by a 7.62 m (25 ft) skiff with a 125-250 horsepower motor. The travel distance will be less than 30.5 m (100 ft). There could be multiple shore-to-barge trips during the day; however, the area of travel will be relatively small and close to shore. We do not expect any of these other in-water construction and heavy machinery activities to take marine mammals. Therefore, these other in-water construction and heavy machinery activities will not be discussed further.

For further details on the proposed action and project components, please refer to Section 1.2 of the application.

Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please see Proposed Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history, of the potentially affected species. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SARs;
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports
) and more general information about these species (
e.g.,
physical and behavioral descriptions) may be found on NMFS's

website (
https://www.fisheries.noaa.gov/find-species
).

Table 2 lists all species with expected potential for occurrence in the project area and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and potential biological removal (PBR), where known. Tagged sperm whales have been tracked within the Gulf of Alaska, and multiple whales have been tracked in Chatham Strait, in Icy Strait, and in the action area in 2014 and 2015 (
http://seaswap.info/whaletrackerAccessed4/15/19
). However, the known sperm whale habitat (these shelf-edge/slope waters of the Gulf of Alaska) are far outside of the action area. It is unlikely that sperm whales will occur in the action area where pile driving activities will occur because they are generally found in far deeper waters. Therefore, sperm whales are not being proposed for take authorization and not discussed further. For taxonomy, we follow Committee on Taxonomy (2020). PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS' SARs). While no mortality is anticipated or authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species and other threats.

Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS's U.S. Pacific and Alaska SARs (Carretta
et al.,
2020; Muto
et al.,
2020). All MMPA stock information presented in Table 2 is the most recent available at the time of publication and is available in the 2019 SARs (Caretta
et al.,
2020; Muto
et al.,
2020) and draft 2020 SARs (available online at:
www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports
).

Table 2—Marine Mammal Occurrence in the Project Area

Common name
Scientific name
Stock

ESA/
MMPA status;
strategic

(Y/N)
1

Stock abundance

(CV, N
min
, most recent

abundance survey)
2

PBR

Annual

M/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, 2016)
801
131

Family Balaenopteridae (rorquals):

Minke Whale

Balaenoptera acutorostrata

Alaska
-, -, N
N/A (see SAR, N/A, see SAR)
UND
0

Humpback Whale

Megaptera novaeangliae

Central N Pacific (Hawaii and Mexico DPS)
-, -, Y
10,103 (0.3, 7,891, 2006)
83
26

Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Delphinidae:

Killer Whale

Orcinus orca

Alaska Resident
-, -, N
2,347 (N/A, 2347, 2012)
24
1

Northern Resident
-, -, N
302 (N/A, 302, 2018)
2.2
0.2

West Coast Transient
-, -, N
349 (na/349; 2018)
3.5
0.4

Pacific White-Sided Dolphin

Lagenorhynchus obliquidens

N Pacific
-, -, N
26,880 (N/A, N/A, 1990)
UND
0

Family Phocoenidae (porpoises):

Dall's Porpoise

Phocoenoides dalli

AK
-, -, N
83,400 (0.097, N/A, 1991)
UND
38

Harbor Porpoise

Phocoena phocoena

Southeast Alaska
-, -, Y
see SAR (see SAR, see SAR, 2012)
see SAR
34

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (Eared Seals and Sea Lions):

Steller Sea Lion

Eumetopias jubatus

Western DPS
E, D, Y
52,932 (see SAR, 52,932, 2019)
318
255

Eastern DPS
T, D, Y
43,201 a (see SAR, 43,201, 2017)
2592
112

Family Phocidae (earless seals):

Harbor Seal

Phoca vitulina

Glacier Bay/Icy Strait
-, -, N
7,455 (see SAR, 6,680, 2017)
120
104

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:
www.nmfs.noaa.gov/pr/sars/.
CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable [explain if this is the case].

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.

All species that could potentially occur in the proposed survey areas are included in Table 2. In addition, the Northern sea otter (
Enhydra lutris kenyoni
) may be found in the project area. However, sea otters are managed by the U.S. Fish and Wildlife Service and are not considered further in this document.

Minke Whale

In the North Pacific Ocean, minke whales occur from the Bering and Chukchi seas south to near the Equator (Leatherwood
et al.,
1982). In the northern part of their range, minke whales are believed to be migratory, whereas, they appear to establish home ranges in the inland waters of Washington and along central California (Dorsey
et al.
1990). Minke whales are observed in Alaska's nearshore waters during the summer months (National Park Service (NPS) 2018). Minke whales are usually sighted individually or in small groups of 2-3, but there are reports of loose aggregations of hundreds of animals (NMFS 2018d). Minke whales are rare in the action area, but they could be encountered. During the construction of the first Icy Strait cruise ship berth, a single minke was observed during the 135-day monitoring period (June 2015 through January 2016) (BergerABAM 2016). During Berth II construction there was also only one reported sighting of a minke whale throughout the duration of monitoring (June 2019-October 2019; SolsticeAK 2020).

No abundance estimates have been made for the number of minke whales in the entire North Pacific. However, some information is available on the numbers of minke whales in some areas of Alaska. Line-transect surveys were conducted in shelf and nearshore waters (within 30-45 nautical miles of land) in 2001-2003 from the Kenai Fjords in the Gulf of Alaska to the central Aleutian Islands. Minke whale abundance was estimated to be 1,233 (CV = 0.34) for this area (Zerbini
et al.,
2006). This estimate has also not been corrected for animals missed on the trackline. The majority of the sightings were in the Aleutian Islands, rather than in the Gulf of Alaska, and in water shallower than 200 m. So few minke whales were seen during three offshore Gulf of Alaska surveys for cetaceans in 2009, 2013, and 2015 that a population estimate for this species in this area could not be determined (Rone
et al.,
2017).

Humpback Whale

The humpback whale is distributed worldwide in all ocean basins and a broad geographical range from tropical to temperate waters in the Northern Hemisphere and from tropical to near-ice-edge waters in the Southern Hemisphere. The humpback whales that forage throughout British Colombia and Southeast Alaska undertake seasonal migrations from their tropical calving and breeding grounds in winter to their high-latitude feeding grounds in summer. They may be seen at any time of year in Alaska, but most animals winter in temperate or tropical waters near Hawaii. In the spring, the animals migrate back to Alaska where food is abundant. The Central North Pacific stock of humpback whales are found in the waters of Southeast Alaska and consist of two distinct population segments (DPSs) listed under the ESA, the Hawaii DPS and the Mexico DPS.

Within Southeast Alaska, humpback whales are found throughout all major waterways and in a variety of habitats, including open-ocean entrances, open-strait environments, near-shore waters, area with strong tidal currents, and secluded bays and inlets. They tend to concentrate in several areas, including northern Southeast Alaska. Patterns of occurrence likely follow the spatial and temporal changes in prey abundance and distribution with humpback whales adjusting their foraging locations to areas of high prey density (Clapham 2000).

Humpback whales may be found in and around Chichagof Island, Icy Strait, and Port Frederick Inlet at any given time. While many humpback whales migrate to tropical calving and breeding grounds in winter, they have been observed in Southeast Alaska in all months of the year (Bettridge
et al.,
2015). Diet for humpback whales in the Glacier Bay/Icy Strait area mainly consists of small schooling fish (capelin, juvenile walleye pollock, sand lance, and Pacific herring) rather than
euphausiids
(krill). They migrate to the northern reaches of Southeast Alaska (Glacier Bay) during spring and early summer following these fish and then move south towards Stephens Passage in early fall to feed on krill, passing the project area on the way (Krieger and Wing 1986). Over 32 years of humpback whale monitoring in the Glacier Bay/Icy Strait area reveals a substantial decline in population since 2014; a total of 164 individual whales were documented in 2016 during surveys conducted from June-August, making it the lowest count since 2008 (Neilson
et al.,
2017).

During construction of the first Icy Strait cruise ship berth from June 2015 through January 2016, humpback whales were observed in the action area on 84 of the 135 days of monitoring; most often in September and October. Up to 18 humpback sightings were reported on a single day (October 2, 2015), and a total of 226 Level B harassments were recorded during project construction (June 2015 through January 2016) (BergerABAM 2016). Additionally, during construction of Icy Strait cruise ship Berth II in 2019, humpback whales were observed in the action area on 45 of the 51 days of monitoring; most often in July and September. Up to 24 humpback sightings were reported on a single day (July 30, 2019) during project construction (SolsticeAK 2020). In the project vicinity, humpback whales typically occur in groups of 1-2 animals, with an estimated maximum group size of 8 animals.

On October 9, 2019, a proposed rule to designate critical habitat for humpback whales was published in the
Federal Register
(84 FR 54354). Proposed critical habitat for Mexico DPS humpback whales was divided into ten units and assigned a conservation rating based upon available data for the unit. Unit 10 encompasses Southeast Alaska, including Port Frederick and Icy Strait. The area is of medium conservation importance on a scale from very low to very high.

Gray Whale

Gray whales are found exclusively in the North Pacific Ocean. The Eastern North Pacific stock of gray whales inhabit the Chukchi, Beaufort, and Bering Seas in northern Alaska in the summer and fall and California and Mexico in the winter months, with a migration route along the coastal waters of Southeast Alaska. Gray whales have also been observed feeding in waters off Southeast Alaska during the summer (NMFS 2018e).

The migration pattern of gray whales appears to follow a route along the western coast of Southeast Alaska, traveling northward from British Columbia through Hecate Strait and Dixon Entrance, passing the west coast of Chichagof Island from late March to May (Jones
et al.
1984, Ford
et al.
2013). Since the project area is on the east coast of Chichagof Island it is less likely there will be gray whales sighted during project construction; however, the possibility exists.

During the 2016 construction of the first cruise ship terminal at Icy Strait Point and 2019 construction of cruise ship Berth II, no gray whales were seen monitoring periods (BergerABAM 2016; SolsticeAK 2020).

Killer Whale

Killer whales have been observed in all oceans and seas of the world, but the highest densities occur in colder and more productive waters found at high latitudes. Killer whales are found throughout the North Pacific and occur along the entire Alaska coast, in British Columbia and Washington inland waterways, and along the outer coasts of Washington, Oregon, and California (NMFS 2018f).

The Alaska Resident stock occurs from Southeast Alaska to the Aleutian Islands and Bering Sea. The Northern Resident stock occurs from Washington State through part of Southeast Alaska; and the West Coast Transient stock occurs from California through Southeast Alaska (Muto
et al.,
2018) and are thought to occur frequently in Southeast Alaska (Straley 2017).

Transient killer whales can pass through the waters surrounding Chichagof Island, in Icy Strait and Glacier Bay, feeding on marine mammals. Because of their transient nature, it is difficult to predict when they will be present in the area. Whales from the Alaska Resident stock and the Northern Resident stock are thought to primarily feed on fish. Like the transient killer whales, they can pass through Icy Strait at any given time (North Gulf Oceanic Society 2018).

Killer whales were observed on 11 days during construction of the first Icy Strait cruise ship berth during the135-day monitoring period (June 2015 through January 2016). Killer whales were observed a few times a month. Usually a singular animal was observed, but a group containing 8 individuals was seen in the action area on one occasion, for a total of 24 animals observed during in-water work (BergerABAM 2016). During construction of the second Icy Strait cruise ship Berth II in 2019 (51 days), killer whales were observed on 8 days. Usually a single animal or pairs were observed, but a group containing 5 individuals was seen in the action area on one occasion. A total of 20 animals observed during in-water work on Berth II (SolsticeAK 2020).

Pacific White-Sided Dolphin

Pacific white-sided dolphins are a pelagic species. They are found throughout the temperate North Pacific Ocean, north of the coasts of Japan and Baja California, Mexico (Muto
et al.,
2018). They are most common between the latitudes of 38° North and 47° North (from California to Washington). The distribution and abundance of Pacific white-sided dolphins may be affected by large-scale oceanographic occurrences, such as El Niño, and by underwater acoustic deterrent devices (NPS 2018a).

No Pacific white-sided dolphins were observed during construction of the first cruise ship berth during the135-day monitoring period (June 2015 through January 2016) (BergerABAM 2016). However, a pod of two Pacific white-sided dolphins were observed during construction of the second cruise ship Berth II (June 2019 through October 2019) (SolsticeAK 2020). They are rare in the action area, likely because they are pelagic and prefer more open water habitats than are found in Icy Strait and Port Frederick Inlet. Pacific white-sided dolphins have been observed in Alaska waters in groups ranging from 20 to 164 animals, with the sighting of 164 animals occurring in Southeast Alaska near Dixon Entrance (Muto
et al.,
2018).

Dall's Porpoise

Dall's porpoises are widely distributed across the entire North Pacific Ocean. They show some migration patterns, inshore and offshore and north and south, based on morphology and type, geography, and seasonality (Muto
et al.,
2018). They are common in most of the larger, deeper channels in Southeast Alaska and are rare in most narrow waterways, especially those that are relatively shallow and/or with no outlets (Jefferson
et al.,
2019). In Southeast Alaska, abundance varies with season.

Jefferson
et al.
(2019) recently published a report with survey data spanning from 1991 to 2012 that studied Dall's porpoise density and abundance in Southeast Alaska. They found Dall's porpoise were most abundant in spring, observed with lower numbers in summer, and lowest in fall. Surveys found Dall's porpoise to be common in Icy Strait and sporadic with very low densities in Port Frederick (Jefferson
et al.,
2019). During a 16-year survey of cetaceans in Southeast Alaska, Dall's porpoises were commonly observed during spring, summer, and fall in the nearshore waters of Icy Strait (Dahlheim
et al.,
2009). Dall's porpoises were observed on 2 days during the 135-day monitoring period (June 2015 through January 2016) of the construction of the first cruise ship berth (BergerABAM 2016). Both were single individuals transiting within the waters of Port Frederick in the vicinity of Halibut Island. During the second cruise ship Berth II construction a total of 21 Dall's porpoises were observed on 8 days (SolsticeAK 2020). Dall's porpoises generally occur in groups from 2-12 individuals (NMFS 2018g).

Harbor Porpoise

In the eastern North Pacific Ocean, the Bering Sea and Gulf of Alaska harbor porpoise stocks range from Point Barrow, along the Alaska coast, and the west coast of North America to Point Conception, California. The Southeast Alaska stock ranges from Cape Suckling, Alaska to the northern border of British Columbia. Within the inland waters of Southeast Alaska, harbor porpoises' distribution is clustered with greatest densities observed in the Glacier Bay/Icy Strait region and near Zarembo and Wrangell Islands and the adjacent waters of Sumner Strait (Dahlheim
et al.,
2015). Harbor porpoises also were observed primarily between June and September during construction of the Hoonah Berth I cruise ship terminal project. Harbor porpoises were observed on 19 days during the 135-day monitoring period (June 2015 through January 2016) (BergerABAM 2016) and seen either singularly or in groups from two to four animals. During the test pile program conducted at the Berth II project site in May 2018, eight harbor porpoises where observed over a 7-hour period (SolsticeAK 2018).

There is no official stock abundance associated with the SARs for harbor porpoise. Both aerial and vessel based surveys have been conducted for this species. Aerial surveys of this stock were conducted in June and July 1997 and resulted in an observed abundance estimate of 3,766 harbor porpoise (Hobbs and Waite 2010) and the surveys included a subset of smaller bays and inlets. Correction factors for observer perception bias and porpoise availability at the surface were used to develop an estimated corrected abundance of 11,146 harbor porpoise in the coastal and inside waters of Southeast Alaska (Hobbs and Waite 2010). Vessel based spanning the 22-year study (1991-2012) found the relative abundance of harbor porpoise varied in the inland waters of Southeast Alaska. Abundance estimated in 1991-1993 (N = 1,076; percent CI = 910-1,272) was higher than the estimate obtained for 2006-2007 (N = 604; 95 percent CI = 468-780) but comparable to the estimate for 2010-2012 (N = 975; 95 percent CI = 857-1,109; Dahlheim
et al.,
2015). These estimates assume the probability of detection directly on the trackline to be unity (g(0) = 1) because estimates of g(0) could not be computed for these surveys. Therefore, these abundance estimates may be biased low to an unknown degree. A range of possible g(0) values for harbor porpoise vessel surveys in other regions is 0.5-0.8 (Barlow 1988, Palka 1995), suggesting that as much as 50 percent of the porpoise can be missed, even by experienced observers.

Further, other vessel based survey data (2010-2012) for the inland waters of Southeast Alaska, calculated abundance estimates for the concentrations of harbor porpoise in the northern and southern regions of the inland waters (Dahlheim
et al.
2015). The resulting abundance estimates are 398 harbor porpoise (CV = 0.12) in the northern inland waters (including Cross Sound, Icy Strait, Glacier Bay, Lynn

Canal, Stephens Passage, and Chatham Strait) and 577 harbor porpoise (CV = 0.14) in the southern inland waters (including Frederick Sound, Sumner Strait, Wrangell and Zarembo Islands, and Clarence Strait as far south as Ketchikan). Because these abundance estimates have not been corrected for g(0), these estimates are likely underestimates.

The vessel based surveys are not complete coverage of harbor porpoise habitat and not corrected for bias and likely underestimate the abundance. Whereas, the aerial survey in 1997, although outdated, had better coverage of the range and is likely to be more of an accurate representation of the stock abundance (11,146 harbor porpoise) in the coastal and inside waters of Southeast Alaska.

Harbor Seal

Harbor seals range from Baja California north along the west coasts of Washington, Oregon, California, British Columbia, and Southeast Alaska; west through the Gulf of Alaska, Prince William Sound, and the Aleutian Islands; and north in the Bering Sea to Cape Newenham and the Pribilof Islands. They haul out on rocks, reefs, beaches, and drifting glacial ice and feed in marine, estuarine, and occasionally fresh waters. Harbor seals are generally non-migratory and, with local movements associated with such factors as tide, weather, season, food availability and reproduction.

Distribution of the Glacier Bay/Icy Strait stock, the only stock considered in this application, ranges along the coast from Cape Fairweather and Glacier Bay south through Icy Strait to Tenakee Inlet on Chichagof Island (Muto
et al.,
2018).

The Glacier Bay/Icy Strait stock of harbor seals are common residents of the action area and can occur on any given day in the area, although they tend to be more abundant during the fall months (Womble and Gende 2013). A total of 63 harbor seals were seen during 19 days of the 135-day monitoring period (June 2015 through January 2016) (BergerABAM 2016), while none were seen during the 2018 test pile program (SolsticeAK 2018). Harbor seals were primarily observed in summer and early fall (June to September). Harbor seals were seen singulary and in groups of two or more, but on one occasion, 22 individuals were observed hauled out on Halibut Rock, across Port Frederick approximately 2,414 m (1.5 miles) from the location of pile installation activity (BergerABAM 2016). In 2019, a total of 33 harbor seals were seen during the Berth II project (SolsticeAK 2020).

There are two known harbor seal haulouts within the project area. According to the AFSC list of harbor seal haulout locations, the closest listed haulout (id 1,349: Name CF39A) is located in Port Frederick, approximately 3,400 m west of the project area (AFSC 2018). The second haulout (id: 8; name: CE79A) is approximately 10,200 meters south of the project area (AFSC 2020).

Steller Sea Lion

Steller sea lions range along the North Pacific Rim from northern Japan to California, with centers of abundance in the Gulf of Alaska and Aleutian Islands (Loughlin
et al.,
1984).

Of the two Steller sea lion populations in Alaska, the Eastern DPS includes sea lions born on rookeries from California north through Southeast Alaska and the Western DPS includes those animals born on rookeries from Prince William Sound westward, with an eastern boundary set at 144° W (NMFS 2018h). Both WDPS and EDPS Steller sea lions are considered in this application because the WDPS are common within the geographic area under consideration (north of Summer Strait) (Fritz
et al.,
2013, NMFS 2013).

Steller sea lions are not known to migrate annually, but individuals may widely disperse outside of the breeding season (late-May to early-July), leading to intermixing of stocks (Jemison
et al.
2013; Allen and Angliss 2015).

Steller sea lions are common in the inside waters of Southeast Alaska. They are residents of the project vicinity and are common year-round in the action area, moving their haulouts based on seasonal concentrations of prey from exposed rookeries nearer the open Pacific Ocean during the summer to more protected sites in the winter (Alaska Department of Fish & Game (ADF&G) 2018). During the construction of the existing Icy Strait cruise ship berth a total of 180 Steller sea lions were observed on 47 days of the 135 monitoring days, amounting to an average of 1.3 sightings per day (BergerABAM 2016). Steller sea lions were frequently observed in groups of two or more individuals, but lone individuals were also observed regularly (BergerABAM 2016). During a test pile program performed at the project location by the Hoonah Cruise Ship Dock Company in May 2018, a total of 15 Steller sea lions were seen over the course of 7 hours in one day (SolsticeAK 2018). During construction of Berth II, a total of 197 Steller sea lion sightings over 42 days in 2019 were reported, amounting to an average of 4.6 sightings per day (SolsticeAK2020). They can occur in groups of 1-10 animals, but may congregate in larger groups near rookeries and haulouts (NMFS 2018h). No documented rookeries or haulouts are near the project area.

Critical habitat has been defined in Southeast Alaska at major haulouts and major rookeries (50 CFR 226.202). The nearest rookery is on the White Sisters Islands near Sitka and the nearest major haulouts are at Benjamin Island, Cape Cross, and Graves Rocks. The White Sisters rookery is located on the west side of Chichagof Island, about 72 km southwest of the project area. Benjamin Island is about 60 km northeast of Hoonah. Cape Cross and Graves Rocks are both about 70 km west of Hoonah. Steller sea lions are known to haul out on land, docks, buoys, and navigational markers.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities (
e.g.,
Richardson
et al.,
1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall
et al.
(2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes (
i.e.,
low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall
et al.
(2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 3.

Table 3—Marine Mammal Hearing Groups
[NMFS, 2018]

Hearing group
Generalized hearing range *

Low-frequency (LF) cetaceans (baleen whales)
7 Hz to 35 kHz.

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)
150 Hz to 160 kHz.

High-frequency (HF) cetaceans (true porpoises,
Kogia,
river dolphins, cephalorhynchid,
Lagenorhynchus cruciger
&
L. australis
)

275 Hz to 160 kHz.

Phocid pinnipeds (PW) (underwater) (true seals)
50 Hz to 86 kHz.

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)
60 Hz to 39 kHz.

* 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 (Hemilä
et al.,
2006; Kastelein
et al.,
2009; Reichmuth and Holt, 2013).

For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. Nine marine mammal species (seven cetacean and two pinniped (one otariid and one phocid) species) have the reasonable potential to occur during the proposed activities. Please refer to Table 2. Of the cetacean species that may be present, three are classified as low-frequency cetaceans (
i.e.,
all mysticete species), two are classified as mid-frequency cetaceans (
i.e.,
all delphinid species), and two are classified as high-frequency cetaceans (
i.e.,
harbor porpoise and Dall's porpoise).

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.

Acoustic effects on marine mammals during the specified activity can occur from vibratory and impact pile driving as well as during DTH of the piles. The effects of underwater noise from the City's proposed activities have the potential to result in Level B behavioral harassment of marine mammals in the vicinity of the action area.

Description of Sound Sources

This section contains a brief technical background on sound, on the characteristics of certain sound types, and on metrics used in this proposal inasmuch as the information is relevant to the specified activity and to a discussion of the potential effects of the specified activity on marine mammals found later in this document. For general information on sound and its interaction with the marine environment, please see,
e.g.,
Au and Hastings (2008); Richardson
et al.
(1995); Urick (1983).

Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in hertz (Hz) or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the decibel (dB). A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal (μPa)), and is a logarithmic unit that accounts for large variations in amplitude; therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa), while the received level is the SPL at the listener's position (referenced to 1 μPa).

Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Root mean square is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average (Urick, 1983). Root mean square accounts for both positive and negative values; squaring the pressures makes all values positive so that they may be accounted for in the summation of pressure levels (Hastings and Popper, 2005). This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures.

Sound exposure level (SEL; represented as dB re 1 μPa
2
-s) represents the total energy in a stated frequency band over a stated time interval or event, and considers both intensity and duration of exposure. The per-pulse SEL is calculated over the time window containing the entire pulse (
i.e.,
100 percent of the acoustic energy). SEL is a cumulative metric; it can be accumulated over a single pulse, or calculated over periods containing multiple pulses. Cumulative SEL represents the total energy accumulated by a receiver over a defined time window or during an event. Peak sound pressure (also referred to as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source, and is represented in the same units as the rms sound pressure.

When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams or may radiate in all directions

(omnidirectional sources), as is the case for sound produced by the pile driving activity considered here. The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones.

Even in the absence of sound from the specified activity, the underwater environment is typically loud due to ambient sound, which is defined as environmental background sound levels lacking a single source or point (Richardson
et al.,
1995). The sound level of a region is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical (
e.g.,
wind and waves, earthquakes, ice, atmospheric sound), biological (
e.g.,
sounds produced by marine mammals, fish, and invertebrates), and anthropogenic (
e.g.,
vessels, dredging, construction) sound. A number of sources contribute to ambient sound, including wind and waves, which are a main source of naturally occurring ambient sound for frequencies between 200 Hz and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient sound levels tend to increase with increasing wind speed and wave height. Precipitation can become an important component of total sound at frequencies above 500 Hz, and possibly down to 100 Hz during quiet times. Marine mammals can contribute significantly to ambient sound levels, as can some fish and snapping shrimp. The frequency band for biological contributions is from approximately 12 Hz to over 100 kHz. Sources of ambient sound related to human activity include transportation (surface vessels), dredging and construction, oil and gas drilling and production, geophysical surveys, sonar, and explosions. Vessel noise typically dominates the total ambient sound for frequencies between 20 and 300 Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz and, if higher frequency sound levels are created, they attenuate rapidly.

The sum of the various natural and anthropogenic sound sources that comprise ambient sound at any given location and time depends not only on the source levels (as determined by current weather conditions and levels of biological and human activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 decibels (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.

Sounds are often considered to fall into one of two general types: Pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing (
e.g.,
Ward, 1997 in Southall
et al.,
2007). Please see Southall
et al.
(2007) for an in-depth discussion of these concepts. The distinction between these two sound types is not always obvious, as certain signals share properties of both pulsed and non-pulsed sounds. A signal near a source could be categorized as a pulse, but due to propagation effects as it moves farther from the source, the signal duration becomes longer (
e.g.,
Greene and Richardson, 1988).

Pulsed sound sources (
e.g.,
airguns, explosions, gunshots, sonic booms, impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed 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.

Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or intermittent (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses (
e.g.,
rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems. The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment.

The impulsive sound generated by impact hammers is characterized by rapid rise times and high peak levels. Vibratory hammers produce non-impulsive, continuous noise at levels significantly lower than those produced by impact hammers. Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time (
e.g.,
Nedwell and Edwards, 2002; Carlson
et al.,
2005). DTH is believed to produce sound with both impulsive and continuous characteristics (
e.g.,
Denes
et al.,
2016).

Acoustic Effects on Marine Mammals

We previously provided general background information on marine mammal hearing (see Description of Marine Mammals in the Area of Specified Activities). Here, we discuss the potential effects of sound on marine mammals.

Note that, in the following discussion, we refer in many cases to a review article concerning studies of noise-induced hearing loss conducted from 1996-2015 (
i.e.,
Finneran, 2015). For study-specific citations, please see that work. Anthropogenic sounds cover a broad range of frequencies and sound levels and can have a range of highly variable impacts on marine life, from none or minor to potentially severe responses, depending on received levels, duration of exposure, behavioral context, and various other factors. The potential effects of underwater sound from active acoustic sources can potentially result in one or more of the following: Temporary or permanent hearing impairment, non-auditory physical or physiological effects, behavioral disturbance, stress, and masking (Richardson
et al.,
1995; Gordon
et al.,
2004; Nowacek
et al.,
2007; Southall
et al.,
2007; Götz
et al.,
2009). The degree of effect is intrinsically related to the signal characteristics, received level, distance from the source, and duration of the sound exposure. In general, sudden, high level sounds can cause hearing loss, as can longer exposures to lower level sounds. Temporary or permanent loss of hearing will occur almost exclusively for noise within an animal's hearing range. We first describe specific manifestations of acoustic effects before providing discussion specific to pile driving and removal activities.

Richardson
et al.
(1995) described zones of increasing intensity of effect that might be expected to occur, in relation to distance from a source and assuming that the signal is within an animal's hearing range. First is the area within which the acoustic signal would

be audible (potentially perceived) to the animal but not strong enough to elicit any overt behavioral or physiological response. The next zone corresponds with the area where the signal is audible to the animal and of sufficient intensity to elicit behavioral or physiological responsiveness. Third is a zone within which, for signals of high intensity, the received level is sufficient to potentially cause discomfort or tissue damage to auditory or other systems. Overlaying these zones to a certain extent is the area within which masking (
i.e.,
when a sound interferes with or masks the ability of an animal to detect a signal of interest that is above the absolute hearing threshold) may occur; the masking zone may be highly variable in size.

We describe the more severe effects (
i.e.,
certain non-auditory physical or physiological effects) only briefly as we do not expect that there is a reasonable likelihood that pile driving may result in such effects (see below for further discussion). Potential effects from explosive impulsive sound sources can range in severity from effects such as behavioral disturbance or tactile perception to physical discomfort, slight injury of the internal organs and the auditory system, or mortality (Yelverton
et al.,
1973). Non-auditory physiological effects or injuries that theoretically might occur in marine mammals exposed to high level underwater sound or as a secondary effect of extreme behavioral reactions (
e.g.,
change in dive profile as a result of an avoidance reaction) caused by exposure to sound include neurological effects, bubble formation, resonance effects, and other types of organ or tissue damage (Cox
et al.,
2006; Southall
et al.,
2007; Zimmer and Tyack, 2007; Tal
et al.,
2015). The construction activities considered here do not involve the use of devices such as explosives or mid-frequency tactical sonar that are associated with these types of effects.

Threshold Shift
—Marine mammals exposed to high-intensity sound, or to lower-intensity sound for prolonged periods, can experience hearing threshold shift (TS), which is the loss of hearing sensitivity at certain frequency ranges (Finneran, 2015). TS can be permanent (permanent threshold shift (PTS)), in which case the loss of hearing sensitivity is not fully recoverable, or temporary (TTS), in which case the animal's hearing threshold would recover over time (Southall
et al.,
2007). Repeated sound exposure that leads to TTS could cause PTS. In severe cases of PTS, there can be total or partial deafness, while in most cases the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985).

When PTS occurs, there is physical damage to the sound receptors in the ear (
i.e.,
tissue damage), whereas TTS represents primarily tissue fatigue and is reversible (Southall
et al.,
2007). In addition, other investigators have suggested that TTS is within the normal bounds of physiological variability and tolerance and does not represent physical injury (
e.g.,
Ward, 1997). Therefore, NMFS does not consider TTS to constitute auditory injury.

Relationships between TTS and PTS thresholds have not been studied in marine mammals, and there is no PTS data for cetaceans, but such relationships are assumed to be similar to those in humans and other terrestrial mammals. PTS typically occurs at exposure levels at least several decibels above (a 40-dB threshold shift approximates PTS onset;
e.g.,
Kryter
et al.,
1966; Miller, 1974) that inducing mild TTS (a 6-dB threshold shift approximates TTS onset;
e.g.,
Southall
et al.
2007). Based on data from terrestrial mammals, a precautionary assumption is that the PTS thresholds for impulse sounds (such as impact pile driving pulses as received close to the source) are at least 6 dB higher than the TTS threshold on a peak-pressure basis and PTS cumulative sound exposure level thresholds are 15 to 20 dB higher than TTS cumulative sound exposure level thresholds (Southall
et al.,
2007). Given the higher level of sound or longer exposure duration necessary to cause PTS as compared with TTS, it is considerably less likely that PTS could occur.

TTS is the mildest form of hearing impairment that can occur during exposure to sound (Kryter, 1985). While experiencing TTS, the hearing threshold rises, and a sound must be at a higher level in order to be heard. In terrestrial and marine mammals, TTS can last from minutes or hours to days (in cases of strong TTS). In many cases, hearing sensitivity recovers rapidly after exposure to the sound ends. Few data on sound levels and durations necessary to elicit mild TTS have been obtained for marine mammals.

Marine mammal hearing plays a critical role in communication with conspecifics, and interpretation of environmental cues for purposes such as predator avoidance and prey capture. 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. 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 occurs during a time 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.

Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin (
Tursiops truncatus
), beluga whale (
Delphinapterus leucas
), harbor porpoise, and Yangtze finless porpoise (
Neophocoena asiaeorientalis
)) and three species of pinnipeds (northern elephant seal, harbor seal, and California sea lion) exposed to a limited number of sound sources (
i.e.,
mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). TTS was not observed in trained spotted (
Phoca largha
) and ringed (
Pusa hispida
) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth
et al.,
2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran, 2015). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. There are no data available on noise-induced hearing loss for mysticetes. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall
et al.
(2007), Finneran and Jenkins (2012), Finneran (2015), and NMFS (2018).

Behavioral Effects
—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 to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors (
e.g.,
species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors (
e.g.,
Richardson
et al.,
1995; Wartzok
et al.,
2003; Southall
et al.,
2007; Weilgart, 2007; Archer
et al.,
2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors

(Ellison
et al.,
2012), and can vary depending on characteristics associated with the sound source (
e.g.,
whether it is moving or stationary, number of sources, distance from the source). Please see Appendices B-C of Southall
et al.
(2007) for a review of studies involving marine mammal behavioral responses to sound.

Habituation can occur when an animal's response to a stimulus wanes with repeated exposure, usually in the absence of unpleasant associated events (Wartzok
et al.,
2003). Animals are most likely to habituate to sounds that are predictable and unvarying. It is important to note that habituation is appropriately considered as a “progressive reduction in response to stimuli that are perceived as neither aversive nor beneficial,” rather than as, more generally, moderation in response to human disturbance (Bejder
et al.,
2009). The opposite process is sensitization, when an unpleasant experience leads to subsequent responses, often in the form of avoidance, at a lower level of exposure. As noted, behavioral state may affect the type of response. For example, animals that are resting may show greater behavioral change in response to disturbing sound levels than animals that are highly motivated to remain in an area for feeding (Richardson
et al.,
1995; NRC, 2003; Wartzok
et al.,
2003). Controlled experiments with captive marine mammals have showed pronounced behavioral reactions, including avoidance of loud sound sources (Ridgway
et al.,
1997; Finneran
et al.,
2003). Observed responses of wild marine mammals to loud pulsed sound sources (typically airguns or acoustic harassment devices) have been varied but often consist of avoidance behavior or other behavioral changes suggesting discomfort (Morton and Symonds, 2002; see also Richardson
et al.,
1995; Nowacek
et al.,
2007). However, many delphinids approach low-frequency airgun source vessels with no apparent discomfort or obvious behavioral change (
e.g.,
Barkaszi
et al.,
2012), indicating the importance of frequency output in relation to the species' hearing sensitivity.

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, l
et al
one 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.

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; Gailey
et al.,
2016).

Marine mammals vocalize for different purposes and across multiple modes, such as whistling, echolocation click production, calling, and singing. Changes in vocalization behavior in response to anthropogenic noise can occur for any of these modes and may result from a need to compete with an increase in background noise or may reflect increased vigilance or a startle response. For example, in the presence of potentially masking signals, humpback whales and killer whales have been observed to increase the length of their songs (Miller
et al.,
2000; Fristrup
et al.,
2003; Foote
et al.,
2004), while right whales 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 airgun 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). The result of a flight response could range from brief, temporary exertion and displacement from the area where the signal provokes flight to, in extreme cases, marine mammal strandings (Evans and England, 2001). However, it should be noted that response to a perceived predator does not necessarily invoke flight (Ford and Reeves, 2008), and whether individuals are solitary or in groups may influence the response.

Behavioral disturbance can also impact marine mammals in more subtle ways. Increased vigilance may result in costs related to diversion of focus and attention (
i.e.,
when a response consists of increased vigilance, it may come at the cost of decreased attention to other critical behaviors such as foraging or resting). These effects have generally not been demonstrated for marine mammals, but studies involving fish and terrestrial animals have shown that increased vigilance may substantially reduce feeding rates (
e.g.,
Beauchamp and Livoreil, 1997; Fritz
et al.,
2002; Purser and Radford, 2011). In addition, chronic disturbance can cause population declines through reduction of fitness (
e.g.,
decline in body condition) and subsequent reduction in reproductive success, survival, or both (
e.g.,
Harrington and Veitch, 1992; Daan
et al.,
1996; Bradshaw
et al.,
1998). However, Ridgway
et al.
(2006) reported that increased vigilance in bottlenose dolphins exposed to sound over a five-day period did not cause any sleep deprivation or stress effects.

Many animals perform vital functions, such as feeding, resting, traveling, and socializing, on a diel cycle (24-hour cycle). Disruption of such functions resulting from reactions to stressors such as sound exposure are more likely to be significant if they last more than one diel cycle or recur on subsequent days (Southall
et al.,
2007). Consequently, a behavioral response lasting less than one day and not recurring on subsequent days is not considered particularly severe unless it could directly affect reproduction or survival (Southall
et al.,
2007). Note that there is a difference between multi-day substantive behavioral reactions and multi-day anthropogenic activities. For example, just because an activity lasts for multiple days does not necessarily mean that individual animals are either exposed to activity-related stressors for multiple days or, further, exposed in a manner resulting in sustained multi-day substantive behavioral responses.

Stress Responses
—An animal's perception of a threat may be sufficient to trigger stress responses consisting of some combination of behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses (
e.g.,
Seyle, 1950; Moberg, 2000). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness.

Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance (
e.g.,
Moberg, 1987; Blecha, 2000). Increases in the circulation of glucocorticoids are also equated with stress (Romano
et al.,
2004).

The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and “distress” is the cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose serious fitness consequences. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other functions. This state of distress will last until the animal replenishes its energetic reserves sufficient to restore normal function.

Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well-studied through controlled experiments and for both laboratory and free-ranging animals (
e.g.,
Holberton
et al.,
1996; Hood
et al.,
1998; Jessop
et al.,
2003; Krausman
et al.,
2004; Lankford
et al.,
2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker, 2000; Romano
et al.,
2002b) and, more rarely, studied in wild populations (
e.g.,
Romano
et al.,
2002a). For example, Rolland
et al.
(2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as “distress.” In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003).

Auditory Masking
—Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest (
e.g.,
those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson
et al.,
1995; Erbe
et al.,
2016). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural (
e.g.,
snapping shrimp, wind, waves, precipitation) or anthropogenic (
e.g.,
shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest (
e.g.,
signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities (
e.g.,
sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions.

Under certain circumstances, marine mammals experiencing significant masking could also be impaired from maximizing their performance fitness in survival and reproduction. Therefore, when the coincident (masking) sound is man-made, it may be considered harassment when disrupting or altering critical behaviors. It is important to distinguish TTS and PTS, which persist after the sound exposure, from masking, which occurs during the sound exposure. Because masking (without resulting in TS) is not associated with abnormal physiological function, it is not considered a physiological effect, but rather a potential behavioral effect.

The frequency range of the potentially masking sound is important in determining any potential behavioral impacts. For example, low-frequency signals may have less effect on high-frequency echolocation sounds produced by odontocetes but are more likely to affect detection of mysticete communication calls and other

potentially important natural sounds such as those produced by surf and some prey species. The masking of communication signals by anthropogenic noise may be considered as a reduction in the communication space of animals (
e.g.,
Clark
et al.,
2009) and may result in energetic or other costs as animals change their vocalization behavior (
e.g.,
Miller
et al.,
2000; Foote
et al.,
2004; Parks
et al.,
2007; Di Iorio and Clark, 2009; Holt
et al.,
2009). Masking can be reduced in situations where the signal and noise come from different directions (Richardson
et al.,
1995), through amplitude modulation of the signal, or through other compensatory behaviors (Houser and Moore, 2014). Masking can be tested directly in captive species (
e.g.,
Erbe, 2008), but in wild populations it must be either modeled or inferred from evidence of masking compensation. There are few studies addressing real-world masking sounds likely to be experienced by marine mammals in the wild (
e.g.,
Branstetter
et al.,
2013).

Masking affects both senders and receivers of acoustic signals and can potentially have long-term chronic effects on marine mammals at the population level as well as at the individual level. Low-frequency ambient sound levels have increased by as much as 20 dB (more than three times in terms of SPL) in the world's ocean from pre-industrial periods, with most of the increase from distant commercial shipping (Hildebrand, 2009). All anthropogenic sound sources, but especially chronic and lower-frequency signals (
e.g.,
from vessel traffic), contribute to elevated ambient sound levels, thus intensifying masking.

Potential Effects of the City's Activity
—As described previously, the City proposes to conduct pile driving, including impact and vibratory driving (inclusive of DTH). The effects of pile driving on marine mammals are dependent on several factors, including the size, type, and depth of the animal; the depth, intensity, and duration of the pile driving sound; the depth of the water column; the substrate of the habitat; the standoff distance between the pile and the animal; and the sound propagation properties of the environment. With both types, it is likely that the pile driving could result in temporary, short term changes in an animal's typical behavioral patterns and/or avoidance of the affected area. These behavioral changes may include (Richardson
et al.,
1995): Changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where sound sources are located; and/or flight responses.

The biological significance of many of these behavioral disturbances is difficult to predict, especially if the detected disturbances appear minor. However, the consequences of behavioral modification could be expected to be biologically significant if the change affects growth, survival, or reproduction. Significant behavioral modifications that could lead to effects on growth, survival, or reproduction, such as drastic changes in diving/surfacing patterns or significant habitat abandonment are extremely unlikely in this area (
i.e.,
shallow waters in modified industrial areas).

Whether impact or vibratory driving, sound sources would be active for relatively short durations, with relation to potential for masking. The frequencies output by pile driving activity are lower than those used by most species expected to be regularly present for communication or foraging. We expect insignificant impacts from masking, and any masking event that could possibly rise to Level B harassment under the MMPA would occur concurrently within the zones of behavioral harassment already estimated for vibratory and impact pile driving, and which have already been taken into account in the exposure analysis.

Anticipated Effects on Marine Mammal Habitat

The proposed activities would not result in permanent impacts to habitats used directly by marine mammals. The project location is within an area that is currently used by large shipping vessels and in between two existing, heavily-traveled docks, and within an active marine commercial and tourist area.

The proposed activities may have potential short-term impacts to food sources such as forage fish. The proposed activities could also affect acoustic habitat (see masking discussion above), but meaningful impacts are unlikely. There are no known foraging hotspots, or other ocean bottom structures of significant biological importance to marine mammals present in the marine waters in the vicinity of the project area. Therefore, the main impact issue associated with the proposed activity would be temporarily elevated sound levels and the associated direct effects on marine mammals, as discussed previously. The most likely impact to marine mammal habitat occurs from pile driving effects on likely marine mammal prey (
i.e.,
fish) near where the piles are installed. Impacts to the immediate substrate during installation and removal of piles are anticipated, but these would be limited to minor, temporary suspension of sediments, which could impact water quality and visibility for a short amount of time, but which would not be expected to have any effects on individual marine mammals. Impacts to substrate are therefore not discussed further.

Effects to Prey
—Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species (
e.g.,
crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies by species, season, and location and, for some, is not well documented. Here, we describe studies regarding the effects of noise on known marine mammal prey.

Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning (
e.g.,
Zelick
et al.,
1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay
et al.,
2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.

Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation (
e.g.,
feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish, although several are based on studies in support of large, multiyear bridge construction projects (
e.g.,
Scholik and Yan, 2001, 2002; Popper and Hastings, 2009).

Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs (
e.g.,
Fewtrell and McCauley, 2012; Pearson
et al.,
1992; Skalski
et al.,
1992; Santulli
et al.,
1999; Paxton
et al.,
2017). However, some studies have shown no or slight reaction to impulse sounds (
e.g.,
Pena
et al.,
2013; Wardle
et al.,
2001; Jorgenson and Gyselman, 2009; Cott
et al.,
2012). More commonly, though, the impacts of noise on fish are temporary.

SPLs of sufficient strength have been known to cause injury to fish and fish mortality. However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen
et al.
(2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Halvorsen
et al.,
2012b; Casper
et al.,
2013).

The action area supports marine habitat for prey species including large populations of anadromous fish including Pacific salmon (five species), Cutthroat (
Oncorhynchus clarkia
) and Steelhead Trout (
O. mykiss irideus
), and Dolly Varden and other species of marine fish such as halibut, Northern Rock Sole (
Lepidopsetta polyxystra
), sculpins, Pacific Cod (
Gadus macrocephalus
), herring, and Eulachon (
Thaleichthys pacificus
) (NMFS 2020i). The most likely impact to fish from pile driving activities at the project areas would be temporary behavioral avoidance of the area. The duration of fish avoidance of an area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution and behavior is anticipated. In general, impacts to marine mammal prey species are expected to be minor and temporary due to the expected short daily duration of individual pile driving events and the relatively small areas being affected.

The following essential fish habitat (EFH) species may occur in the project area during at least one phase of their lifestage: Chum Salmon (
Oncorhynchus keta
), Pink Salmon (
O. gorbuscha
), Coho Salmon (
O. kisutch
), Sockeye Salmon (
O. nerka
), and Chinook Salmon (
O. tshawytscha
). No habitat areas of particular concern or EFH areas protected from fishing are identified near the project area (NMFS 2020h). The closest documented anadromous fish steams to the project area are Halibut Creek (AWC: 114-34-10200) approximately 5,100 m north west of the proposed project site and Humpback Creek (AWC: 114-34-10100) is approximately 7,600 m southwest of the proposed project site (ADF&G 2020a).

The area impacted by the project is relatively small compared to the available habitat in Port Frederick Inlet and does not include habitat of particular importance relative to available habitat overall. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. As described in the preceding, the potential for the City's construction to affect the availability of prey to marine mammals or to meaningfully impact the quality of physical or acoustic habitat is considered to be insignificant. Effects to habitat will not be discussed further in this document.

Estimated Take

This section provides an estimate of the number of incidental takes proposed for authorization through this IHA, which will inform both NMFS' consideration of “small numbers” and the negligible impact determination.

Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).

Take of marine mammals incidental to the City's pile driving and removal activities (as well as during DTH) could occur as a result of Level A and Level B harassment. Below we describe how the potential take is estimated. As described previously, no mortality is anticipated or proposed to be authorized for this activity. Below we describe how the take is estimated.

Generally speaking, we estimate take by considering: (1) Acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and, (4) and the number of days of activities. We note that while these basic factors can contribute to a basic calculation to provide an initial prediction of takes, additional information that can qualitatively inform take estimates is also sometimes available (
e.g.,
previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the proposed take estimate.

Acoustic Thresholds

Using the best available science, NMFS has developed acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment).

Level B Harassment
—Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source (
e.g.,
frequency, predictability, duty cycle), the environment (
e.g.,
bathymetry), and the receiving animals (hearing, motivation, experience, demography, behavioral context) and can be difficult to predict (Southall
et al.,
2007, Ellison
et al.,
2012). Based on what the available science indicates and the practical need to use a threshold based on a factor that is both predictable and measurable for most activities, NMFS uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS predicts that marine mammals are likely to be behaviorally harassed in a manner we consider Level B harassment when exposed to underwater anthropogenic noise above received levels of 120 dB re 1 μPa (rms) for continuous (
e.g.,
vibratory pile driving and DTH) and above 160 dB re 1 μPa (rms) for impulsive sources (
e.g.,
impact pile driving). The City's proposed activity includes the use of continuous (vibratory pile driving, DTH) and impulsive (impact pile driving) sources, and therefore the 120 and 160 dB re 1 μPa (rms) are applicable.

Level A harassment
—NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different

marine mammal groups (based on hearing sensitivity) as a result of exposure to noise. The technical guidance identifies the received levels, or thresholds, above which individual marine mammals are predicted to experience changes in their hearing sensitivity for all underwater anthropogenic sound sources, and reflects the best available science on the potential for noise to affect auditory sensitivity by:

Dividing sound sources into two groups (
i.e.,
impulsive and non-impulsive) based on their potential to affect hearing sensitivity;

Choosing metrics that best address the impacts of noise on hearing sensitivity,
i.e.,
sound pressure level (peak SPL) and sound exposure level (SEL) (also accounts for duration of exposure); and

Dividing marine mammals into hearing groups and developing auditory weighting functions based on the science supporting that not all marine mammals hear and use sound in the same manner.

These thresholds were developed by compiling and synthesizing the best available science, and are provided in Table 4 below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS 2018 Technical Guidance, which may be accessed at
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

The City's proposed activities includes the use of continuous non-impulsive (vibratory pile driving, DTH) and impulsive (impact pile driving, DTH) sources, and therefore the 120 and 160 dB re 1 μPa (rms) criteria are applicable. DTH pile installation includes drilling (non-impulsive sound) and hammering (impulsive sound) to penetrate rocky substrates (Denes
et al.
2016; Denes
et al.
2019; Reyff and Heyvaert 2019). DTH pile installation was initially thought be a primarily non-impulsive noise source. However, Denes
et al.
(2019) concluded from a study conducted in Virginia, nearby the location for this project, that DTH should be characterized as impulsive based on Southall
et al.
(2007), who stated that signals with a >3 dB difference in sound pressure level in a 0.035-second window compared to a 1-second window can be considered impulsive. Therefore, DTH pile installation is treated as both an impulsive and non-impulsive noise source. In order to evaluate Level A harassment, DTH pile installation activities are evaluated according to the impulsive criteria and using 160 dB rms. Level B harassment isopleths are determined by applying non-impulsive criteria and using the 120 dB rms threshold which is also used for vibratory driving. This approach ensures that the largest ranges to effect for both Level A and Level B harassment are accounted for in the take estimation process.

Table 4—Thresholds Identifying the Onset of Permanent Threshold Shift
[Auditory injury]

Hearing group

PTS onset acoustic thresholds *
(received level)

Impulsive
Non-impulsive

Low-Frequency (LF) Cetaceans

Cell 1: L
pk,flat
:
219 dB;
L
E,LF,24h
:
183 dB

Cell 2: L
E,LF,24h
:
199 dB.

Mid-Frequency (MF) Cetaceans

Cell 3: L
pk,flat
:
230 dB;
L
E,MF,24h
:
185 dB

Cell 4: L
E,MF,24h
:
198 dB.

High-Frequency (HF) Cetaceans

Cell 5: L
pk,flat
:
202 dB;
L
E,HF,24h
:
155 dB

Cell 6: L
E,HF,24h
:
173 dB.

Phocid Pinnipeds (PW) (Underwater)

Cell 7: L
pk,flat
:
218 dB;
L
E,PW,24h
:
185 dB

Cell 8: L
E,PW,24h
:
201 dB.

Otariid Pinnipeds (OW) (Underwater)

Cell 9: L
pk,flat
:
232 dB;
L
E,OW,24h
:
203 dB

Cell 10: L
E,OW,24h
:
219 dB.

* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered.

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

Ensonified Area

Here, we describe operational and environmental parameters of the activity that will feed into identifying the area ensonified above the acoustic thresholds, which include source levels and transmission loss coefficient.

Sound Propagation

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

TL = B * log
10
(R
1
/R
2
),

where:

B = transmission loss coefficient (assumed to be 15)

R
1
= the distance of the modeled SPL from the driven pile, and

R
2
= the distance from the driven pile of the initial measurement.

This formula neglects loss due to scattering and absorption, which is assumed to be zero here. The degree to which underwater sound propagates away from a sound source is dependent on a variety of factors, most notably the water bathymetry and presence or absence of reflective or absorptive conditions including in-water structures and sediments. Spherical spreading occurs in a perfectly unobstructed (free-field) environment not limited by depth or water surface, resulting in a 6 dB reduction in sound level for each doubling of distance from the source (20*log(range)). Cylindrical spreading occurs in an environment in which sound propagation is bounded by the water surface and sea bottom, resulting in a reduction of 3 dB in sound level for each doubling of distance from the source (10*log(range)). As is common practice in coastal waters, here we assume practical spreading loss (4.5 dB

reduction in sound level for each doubling of distance). Practical spreading is a compromise that is often used under conditions where water depth increases as the receiver moves away from the shoreline, resulting in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions.

Sound Source Levels

The intensity of pile driving sounds is greatly influenced by factors such as the type of piles, hammers, and the physical environment in which the activity takes place. There are source level measurements available for certain pile types and sizes from the similar environments recorded from underwater pile driving projects in Alaska (
e.g.,
JASCO Reports—Denes
et al.,
2016 and Austin
et al.,
2016) that were evaluated and used as proxy sound source levels to determine reasonable sound source levels likely result from the City's pile driving and removal activities (Table 5). Many source levels used were more conservation as the values were from larger pile sizes.

Table 5—Proposed Sound Source Levels

Activity
Sound source level at 10 meters
Sound source

Vibratory Pile Driving/Removal

20-in fender pile permanent
30-in steel pile temporary installation
30-in steel pile removal

161.9 SPL
161.9 SPL
161.9 SPL

The 20-in fender and 30-inch-diameter source level for vibratory driving are proxy from median measured source levels from pile driving of 30-inch-diameter piles to construct the Ketchikan Ferry Terminal (Denes
et al.
2016, Table 72).

36-in steel pile permanent
168.2 SPL

The 36-in-diameter pile source level is proxy from median measured source levels from pile driving of 48-in diameter piles for the Port of Anchorage test pile project (Austin
et al.
2016, Table 16).

H-pile installation permanent
168 SPL

The H-pile source level is proxy from median measured source levels from vibratory pile driving of H piles for the Port of Anchorage test pile project (Yurk
et al.
2015 as cited in Denes
et al.
2016, Appendix H Table 2).

Sheet pile installation
160 SPL

The sheet source level is proxy from median measured source levels from vibratory pile driving of 24-in sheets for Berth 30 at the Port of Oakland, CA (Buehler
et al.
2015; Table I.6-2).

Impact Pile Driving

36-in steel pile permanent
186.7 SEL/198.6 SPL

The 36-in diameter pile source level is a proxy from median measured source level from impact hammering of 48-in piles for the Port of Anchorage test pile project (Austin
et al.,
2016, Tables 9 and 16).

20-in fender pile installation permeant
161 SEL/174.8 SPL

The 20-in diameter pile source levels are proxy from median measured source levels from vibratory driving of 24-in piles for the Kodiak Ferry Terminal project (Denes
et al.
2016).

H-pile installation permanent and Sheet pile installation
163 SEL/177 SPL

H-Pile and Sheets Impacting source levels are proxy from median measured source levels from pile driving H-piles and sheets for the Port of Anchorage test pile project (Yurk
et al.
2015 as cited in Denes
et al.
2016, Appendix H Table 1).

DTH Pile Installation

36-in steel pile permanent
20-in fender pile installation temporary
H-pile installation permanent (20-in hole)

164 SEL/166 SPL
154 SEL/166 SPL
154 SEL/166 SPL

The DTH sound source proxy of 164 dB SEL is from 42-in piles, Reyff 2020 and Denes
et al.
2019; while the 154 dB SEL is based on 24-in piles, Denes
et al.
2016.

Level A Harassment

When the NMFS Technical Guidance (2016) was published, in recognition of the fact that ensonified area/volume could be more technically challenging to predict because of the duration component in the new thresholds, we developed a User Spreadsheet that includes tools to help predict a simple isopleth that can be used in conjunction with marine mammal density or occurrence to help predict takes. We note that because of some of the assumptions included in the methods used for these tools, we anticipate that isopleths produced are typically going to be overestimates of some degree, which may result in some degree of overestimate of Level A harassment take. However, these tools offer the best way to predict appropriate isopleths

when more sophisticated 3D modeling methods are not available, and NMFS continues to develop ways to quantitatively refine these tools, and will qualitatively address the output where appropriate. For stationary sources (such as from impact and vibratory pile driving and DTH), NMFS User Spreadsheet (2020) predicts the closest distance at which, if a marine mammal remained at that distance the whole duration of the activity, it would not incur PTS. Inputs used in the User Spreadsheet (Tables 6 and 7), and the resulting isopleths are reported below (Table 8).

Table 6—NMFS Technical Guidance (2020) User Spreadsheet Input To Calculate PTS Isopleths for Vibratory Pile Driving

User spreadsheet input—vibratory pile driving spreadsheet tab A.1 vibratory pile driving used

30-in piles
(temporary
install)

30-in piles
(temporary
removal)

20-in fender piles
(permanent)

36-in piles
(permanent)

H-piles
(permanent)

Sheet piles
(permanent)

Source Level (RMS SPL)
161.9
161.9
161.9
168.2
168
160

Weighting Factor Adjustment (kHz)
2.5
2.5
2.5
2.5
2.5
2.5

Number of piles within 24-hr period
4
4
4
4
4
30

Duration to drive a single pile (min)
15
15
15
15
15
15

Propagation (xLogR)
15
15
15
15
15
15

Distance of source level measurement (meters)
+

10
10
10
10
11
10

Table 7—NMFS Technical Guidance (2020) User Spreadsheet Input To Calculate PTS Isopleths for Impact Pile Driving

User spreadsheet input—impact pile driving spreadsheet tab E.1 impact pile driving used

36-in piles
(permanent)

36-in pile
(DTH)

20-in fender piles
(permanent)

20-in fender pile
(DTH)

H-pile
(permanent)

H-pile
(DTH)

Sheet piles
(permanent)

Source Level (Single Strike/shot SEL)
186.7
164
161
154
163
154
163

Weighting Factor Adjustment (kHz)
2
2
2
2
2
2
2

Number of strikes per pile
100

35

35

35

Strike rate (avg. strikes per second)

15

15

15

Number of piles per day
2
2
2
2
5
2
5

Propagation (xLogR)
15
15
15
15
15
15
15

Distance of source level measurement (meters)
+

10
10
10
10
15
10
15

Table 8—NMFS Technical Guidance (2020) User Spreadsheet Outputs To Calculate Level A Harassment PTS Isopleths

User spreadsheet output
Activity

Sound source level
at 10 m

PTS isopleths
(meters)

Level A harassment
Low-frequency cetaceans
Mid-frequency cetaceans

High-
frequency
cetaceans

Phocid
Otariid

Vibratory Pile Driving/Removal

20-in steel fender pile installation
161.9 SPL
7.8
0.7
11.6
4.8
0.3

30-in steel pile temporary installation
161.9 SPL
7.8
0.7
11.6
4.8
0.3

30-in steel pile removal
161.9 SPL
7.8
0.7
11.6
4.8
0.3

36-in steel permanent installation
168.2 SPL
20.6
1.8
30.5
12.5
0.9

H-pile installation
168 SPL
22.0
2.0
32.5
13.4
0.9

Sheet pile installation
160 SPL
22.4
2.0
33.2
13.6
1.0

Impact Pile Driving

36-in steel permanent installation
186.7 SEL/198.6 SPL
602.7
21.4
717.9
322.5
23.5

20-in fender pile installation
161 SEL/174.8 SPL
5.8
0.2
6.9
3.1
0.21

H-pile installation
163 SEL/177 SPL
21.8
0.8
25.9
11.6
0.8

Sheet pile installation
163 SEL/177 SPL
21.8
0.8
25.9
11.6
0.8

DTH

36-in steel permanent installation
164 SEL/166 SPL
1,225.6
43.6
1,459.9
655.9
47.8

20-in steel fender pile installation
154 SEL/166 SPL
264.1
9.4
314.5
141.3
10.3

H-pile installation
154 SEL/166 SPL
264.1
9.4
314.5
141.3
10.3

Level B Harassment

Utilizing the practical spreading loss model, the City determined underwater noise will fall below the behavioral effects threshold of 120 dB rms for marine mammals at the distances shown in Table 9 for vibratory pile driving/removal, and DTH. With these radial distances, and due to the occurrence of landforms (See Figure 5 and 8 of the IHA Application), the largest Level B harassment zone calculated for vibratory pile driving for 36-in steel piles and H-piles were larger than the 15,700 m from the source where land masses block sound transmission. For DTH, the largest radial distance was 11,659 m. For calculating the Level B harassment zone for impact driving, the practical spreading loss model was used with a behavioral threshold of 160 dB rms. The maximum radial distance of the Level B harassment zone for impact piling equaled 3,744 m for 36-in piles m. Table 9 below provides all Level B harassment radial distances (m) during the City's proposed activities.

Table 9—Radial Distances (Meters) to Relevant Behavioral Isopleths

Activity
Received level at 10 meters

Level B harassment zone
(m) *

Vibratory Pile Driving/Removal

20-in steel fender pile installation
161.9 SPL
6,215 (calculated 6,213).

30-in steel temporary installation
161.9 SPL
6,215 (calculated 6,213).

30-in steel removal
161.9 SPL
6,215 (calculated 6,213).

36-in steel permanent installation
168.2 SPL

15,700
a
(calculated 16,343).

H-pile installation
168 SPL

15,700
a
(calculated 17,434).

Sheet pile installation
160 SPL
4,645 (calculated 4,642).

Impact Pile Driving

20-in fender pile installation
161 SEL/ 174.8 SPL
100 (calculated 97).

36-in steel permanent installation
186.7 SEL/198.6 SPL
3,745 (calculated 3,744).

H-pile and Sheet pile installation
163 SEL/ 177 SPL
205 (calculated 204).

DTH

20-in steel fender pile installation
166 SPL
11,660 (calculated 11,659).

36-in steel temporary installation
166 SPL
11,660 (calculated 11,659).

H-pile installation
166 SPL
11,660 (calculated 11,659).

* Numbers rounded up to nearest 5 meters. These specific rounded distances are for monitoring purposes rather than take estimation.

a
Although the calculated distance to Level B harassment thresholds extends these distances, all Level B harassment zones are truncated at 15,700m from the source where land masses block sound transmission.

Marine Mammal Occurrence and Take Calculation and Estimation

In this section we provide the information about the presence, density, or group dynamics of marine mammals that will inform the take calculations. Potential exposures to impact pile driving, vibratory pile driving/removal and DTH noises for each acoustic threshold were estimated using group size estimates and local observational data. As previously stated, take by Level B harassment as well as small numbers of take by Level A harassment will be considered for this action. Take by Level B and Level A harassment are calculated differently for some species based on monthly or daily sightings data and average group sizes within the action area using the best available data. Take by Level A harassment is being proposed for three species (Dall's and harbor porpoise and harbor seal) where the Level A harassment isopleths are larger for pile driving of 36-in steel piles and DTH of 36-in piles, and is based on average group size multiplied by the number of days of impact pile driving for 36-in piles and DTH of 36-in piles. Distances to Level A harassment thresholds for other project activities (vibratory pile driving/removal, DTH and impact driving of smaller pile sizes) are considerably smaller compared to impact pile driving of 36-in piles and DTH for 36-in piles, and mitigation is expected to avoid Level A harassment from these other activities.

Minke Whales

There are no density estimates of minke whales available in the project area. These whales are usually sighted individually or in small groups of two or three, but there are reports of loose aggregations of hundreds of animals (NMFS 2018). One minke whale was sighted each year during the Hoonah cruise ship Berth I project (June 2015-January 2016; BergerABAM 2016) and during the Hoonah Berth II project (June 2019-October 2019; SolsticeAK 2020).To be conservative based on group size, we predict that three minke whales in a group could be sighted each month over the 4-month project period for a total of 12 minke whale takes proposed for authorization by Level B harassment. No take by Level A harassment is proposed for authorization or anticipated to occur due to their rarer occurrence in the project area.

Humpback Whales

There are no density estimates of humpback whales available in the project area. During the previous Hoonah Berth I project, humpback whales were observed on 84 of the 135 days of monitoring; most often in September and October (BergerABAM 2016). Additionally, during construction of the Hoonah Berth II project in 2019, humpback whales were observed in the action area on 45 of the 51 days of monitoring; most often in July and September. Up to 24 humpback sightings were reported on a single day (July 30, 2019), and a total of 108 observations were recorded in harassment zones during project construction (SolsticeAK 2020).

Based on a group size of eight animals, the general maximum group size observed in Southeast Alaska in all months of the year, NMFS estimates that 8 humpback whales could occur for each day of the project (110 days) for a total of 880 takes by Level B harassment. Under the MMPA, humpback whales are considered a single stock (Central

North Pacific); however, we have divided them here to account for DPSs listed under the ESA. Using the stock assessment from Muto
et al.
2020 for the Central North Pacific stock (10,103 whales) and calculations in Wade
et al.
2016; 9,487 whales are expected to be from the Hawaii DPS and 606 from the Mexico DPS. Therefore, for purposes of consultation under the ESA, we anticipate that 53 of those takes would be of individuals from the Mexico DPS (0.0601 proportion of the total takes). No take by Level A harassment is proposed for authorization or anticipated to occur due to their large size and ability to be visibly detected in the project area if an animal should approach the Level A harassment zone.

Gray Whales

There are no density estimates of gray whales available in the project area. Gray whales travel alone or in small, unstable groups, although large aggregations may be seen in feeding and breeding grounds (NMFS 2018e). Observations in Glacier Bay and nearby waters recorded two gray whales documented over a 10-year period (Keller
et al.,
2017). None were observed during Hoonah Berth I or II project monitoring (BergerABAM 2016, SolsticeAK 2020). We estimate a one gray whale x onesighting per month over the 4-month work period for a total of four gray whale takes proposed for authorization by Level B harassment. No take by Level A harassment is proposed for authorization or anticipated to occur due to their rarer occurrence in the project area, but also their large size and ability to be visibly detected in the project area if an animal should approach the Level A harassment zone.

Killer Whales

There are no density estimates of killer whales available in the project area. Killer whales occur commonly in the waters of the project area, and could include members of several designated stocks that may occur in the vicinity of the proposed project area. Whales are known to use the Icy Strait corridor to enter and exit inland waters and are observed in every month of the year, with certain pods being observed inside Port Frederick passing directly in front of Hoonah. Group size of resident killer whale pods in the Icy Strait area ranges from 42 to 79 and occur in every month of the year (Dahlheim pers. comm. to NMFS 2015). As determined during a line-transect survey by Dalheim
et al.
(2008), the greatest number of transient killer whale observed occurred in 1993 with 32 animals seen over 2 months for an average of 16 sightings per month. Killer whales were observed infrequently during construction of Hoonah Berth I project. Usually a singular animal was observed, but a group containing eight individuals was seen in the project area on one occasion. A total of 24 animals were observed during in-water work for the Hoonah Bert I project (BergerABAM 2016). During construction of the Hoonah Berth II project, killer whales were observed on 8 days. Usually a single animal or pairs were observed, but a group containing five individuals was seen in the project area on one occasion. A total of 20 animals were observed during in-water work on Hoonah Berth II project (SolsticeAK 2020). Using the largest group size for resident killer whales as discussed above, NMFS estimates that 79 killer whales (residents and transients) could occur each month during the 4-month project period for a total of 316 takes by Level B harassment. N

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2021-04431. Public record. Not legal advice.