# 88 FR 74113: Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Naval Magazine Indian Island Ammunition Wharf Maintenance and Pile Replacement Project, Puget Sound, Washington

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URL: https://www.frixlaw.com/law-library/statutes/FR_PRORULE_2023-23737

## Section

- **Citation:** 88 FR 74113
- **Heading:** Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Naval Magazine Indian Island Ammunition Wharf Maintenance and Pile Replacement Project, Puget Sound, Washington
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Federal Register / Vol. 88 / 88 FR 74113

## Text

DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 217 [Docket No. 231023-0251] RIN 0648-BL79 Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Naval Magazine Indian Island Ammunition Wharf Maintenance and Pile Replacement Project, Puget Sound, Washington AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:
Proposed rule, request for comments.

SUMMARY:
NMFS has received a request from the U.S. Navy (Navy) for authorization to take marine mammals incidental to the maintenance and pile replacement construction activities at the Ammunition Wharf at Naval Magazine (NAVMAG) Indian Island in Puget Sound, Washington, over the course of 5 years (2024-2029). As required by the Marine Mammal Protection Act (MMPA), NMFS is proposing regulations to govern that take, and requests comments on the proposed regulations. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision.

DATES:
Comments and information must be received no later than November 29, 2023.

ADDRESSES:
You may submit comments on this document, identified by NOAA-NMFS-2023-0122, by the following method:
• Electronic submission: Submit all electronic public comments via the Federal e-Rulemaking Portal. Go to https://www.regulations.gov and enter NOAA-NMFS-2023-0122 in the Search box, click the “Comment” icon, complete the required fields, and enter or attach your comments.
Instructions: Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on https://www.regulations.gov without change
the “Comment” icon, complete the required fields, and enter or attach your comments.
Instructions: Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on https://www.regulations.gov without change. All personal identifying information ( e.g., name, address), confidential business information, or otherwise sensitive information submitted voluntarily by the sender will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous). Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF file formats only.
FOR FURTHER INFORMATION CONTACT:
Robert Pauline, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Availability of Navy's Application, Marine Mammal Monitoring Plan, and List of References
A copy of the Navy's application, monitoring plan, and any supporting documents, as well as a list of the references cited in this document, may be obtained online at: https:// In case of problems accessing these documents, please call the contact listed above (see FOR FURTHER INFORMATION CONTACT ).
Purpose and Need for Regulatory Action
This proposed rule, if adopted, would establish a framework under the authority of the MMPA (16 U.S.C. 1361 et seq. ) to authorize, for a five-year period (2024-2029), take of marine mammals incidental to the Navy's construction activities associated with maintenance and pile replacement at the Ammunition Wharf at NAVMAG Indian Island.
We received an application from the Navy requesting 5-year regulations and authorization to take multiple species of marine mammals. Take would occur by Level A and Level B harassment incidental to impact and vibratory pile driving. Please see Background below for definitions of harassment
ctivities associated with maintenance and pile replacement at the Ammunition Wharf at NAVMAG Indian Island.
We received an application from the Navy requesting 5-year regulations and authorization to take multiple species of marine mammals. Take would occur by Level A and Level B harassment incidental to impact and vibratory pile driving. Please see Background below for definitions of harassment.
Legal Authority for the Proposed Action
Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region for up to 5 years if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking pursuant to that activity and other means of effecting the “least practicable adverse impact” on the affected species or stocks and their habitat (see the discussion below in the Proposed Mitigation section), as well as monitoring and reporting requirements. Section 101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR part 216, subpart R provide the legal basis for issuing this proposed rule containing 5-year regulations, and for any subsequent letters of authorization (LOAs). As directed by this legal authority, this proposed rule contains mitigation, monitoring, and reporting requirements.
Summary of Major Provisions Within the Proposed Rule
The following is a summary of the major provisions of this proposed rule regarding Navy construction activities
issuing this proposed rule containing 5-year regulations, and for any subsequent letters of authorization (LOAs). As directed by this legal authority, this proposed rule contains mitigation, monitoring, and reporting requirements.
Summary of Major Provisions Within the Proposed Rule
The following is a summary of the major provisions of this proposed rule regarding Navy construction activities. These provisions include measures requiring:
• monitoring of the construction areas to detect the presence of marine mammals before beginning construction activities;
• Shutdown of construction activities under certain circumstances to avoid injury of marine mammals;
• Soft start for impact pile driving to allow marine mammals the opportunity to leave the area prior to beginning impact pile driving at full power; and
• Use of bubble curtains to attenuate sound levels when impact driving steel piles.
Background
Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1361 et seq. ) directs the Secretary of Commerce (as subsequently 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, regulations are issued, and notice is provided to the public.
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), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth
l 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), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth.
NMFS has defined “negligible impact” in 50 CFR 216.103 as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.
Except with respect to certain activities not pertinent here, the MMPA defines “harassment” as any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).
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 promulgation of regulations and subsequent issuance of an incidental take authorization with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified in Categorical Exclusion B4 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
This action is consistent with categories of activities identified in Categorical Exclusion B4 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 rule qualifies to be categorically excluded from further NEPA review.
Information in the Navy's application and this document collectively provide the environmental information related to proposed issuance of these regulations and subsequent incidental take authorization for public review and comment. We will review all comments submitted in response to this notice of proposed rulemaking prior to concluding our NEPA process and prior to making a final decision on the request for incidental take authorization.
Summary of Request
In May 2021, NMFS received a request from the Navy requesting authorization to take small numbers of eight species of marine mammals incidental to construction activities at the Ammunition Wharf at NAVMAG Indian Island. The Navy has requested regulations that would establish a process for authorizing such take via an LOA. NMFS reviewed the Navy's application, and sent initial questions regarding the application to the Navy on October 5, 2021. The Navy addressed the questions and submitted a revised LOA application on March 24, 2022. After additional questions were sent by NMFS, the Navy submitted another revised application on May 13, 2022, and the revised application was deemed adequate and complete on June 9, 2022. The application was published for public review and comment on August 4, 2022 (87 FR 47722). Following publication of the application, the Navy delayed the project start date by 1 year.
The Navy requests authorization to take eight species of marine mammals by Level B harassment
her revised application on May 13, 2022, and the revised application was deemed adequate and complete on June 9, 2022. The application was published for public review and comment on August 4, 2022 (87 FR 47722). Following publication of the application, the Navy delayed the project start date by 1 year.
The Navy requests authorization to take eight species of marine mammals by Level B harassment. They have also requested authorization to take one of these species by Level A harassment. Neither the Navy nor NMFS expects serious injury or mortality to result from this activity. The proposed regulations would be valid for 5 years (2024-2029).
Description of Proposed Activity
Overview
The Navy proposes to replace defective structural concrete and fender piles as well as conduct maintenance and repair activities on the Ammunition Wharf at NAVMAG Indian Island. Maintaining this wharf structure is vital to sustaining the Navy's mission and ensuring readiness. The Navy proposes to replace up to 118 structural concrete piles or fender piles, conduct maintenance, and engage in repair activities over a 7-year period on the Ammunition Wharf. However, the proposed LOA would only be valid for 5 years. The Navy plans to conduct necessary work, including impact and vibratory pile driving, to replace and maintain the wharf structure. Under the proposed 5-year LOA, up to 110 structurally unsound structural piles or fender piles would be replaced. Structural concrete piles would be replaced with 24-inch concrete piles and old fender piles would be replaced with 14-inch steel H piles or 18.75-inch composite piles. Up to eight steel piles may also be installed in addition to the structural concrete piles if necessary. The 2 years following the expiration of the LOA would consist of removal and installation of concrete piles, and maintenance and repair work. The Navy would request incidental take authorizations as necessary for the final 2 years of work
ith 14-inch steel H piles or 18.75-inch composite piles. Up to eight steel piles may also be installed in addition to the structural concrete piles if necessary. The 2 years following the expiration of the LOA would consist of removal and installation of concrete piles, and maintenance and repair work. The Navy would request incidental take authorizations as necessary for the final 2 years of work.
Dates and Duration
The proposed regulations would be valid for a period of 5 years from October 1, 2024, until September 30, 2029. All pile driving would be conducted during the prescribed in-water work window of October 1 to January 15 to avoid conducting activities when juvenile salmonids are most likely to be present. A conservative estimate of annual pile driving days over the duration of the 5-year LOA based on the assumption that pile driving rates would be relatively slow would be approximately 24 days per year with up to 22 concrete piles or fender piles, and up to 2 steel piles installed per year. Conservatively, one concrete pile would be installed per day using jetting followed by proofing with an impact hammer. There may be extra days for additional proofing or weather/equipment delays. Actual daily production rates may be higher (often two piles are installed in a day), resulting in fewer actual pile driving days.
Specific Geographic Region
NAVMAG Indian Island is located near Port Hadlock in Jefferson County, Washington, southeast of Port Townsend, at the northeast corner of the Olympic Peninsula (Figure 1). The island is approximately 8 kilometers (km) long and 2 km wide, and comprises approximately 11 km square (km 2 ). NAVMAG Indian Island is located between Port Townsend Bay and Kilisut Harbor. The Federal Government owns the island and provides an easement on a small portion of the southern extent of the island to Washington State Department of Transportation for access to Marrowstone Island along State Route 116
roximately 8 kilometers (km) long and 2 km wide, and comprises approximately 11 km square (km 2 ). NAVMAG Indian Island is located between Port Townsend Bay and Kilisut Harbor. The Federal Government owns the island and provides an easement on a small portion of the southern extent of the island to Washington State Department of Transportation for access to Marrowstone Island along State Route 116. NAVMAG Indian Island is the West Coast ammunition ordnance storage center supporting the U.S. Navy Pacific Fleet.
NAVMAG Indian Island occupies approximately 19 km of shoreline within Port Townsend Bay. There are two marine structures located at NAVMAG Indian Island, the Ammunition Wharf and the Small Craft Pier, but only the Ammunition Wharf activities are addressed in this proposed rule. Its primary mission is to load, offload, and provide storage and logistics management for ordnance used on Navy vessels.
BILLING CODE 3510-22-P EP30OC23.000
BILLING CODE 3510-22-C Detailed Description of the Specified Activity
NAVMAG Indian Island is the West Coast ammunition ordnance storage center supporting the U.S. Navy Pacific Fleet. Its primary mission is to load, offload, and provide storage and logistics management for ordnance used on Navy vessels. Construction of the Ammunition Wharf was completed in 1979, and there are a total of 1,783 piles in the Ammunition Wharf: 1,391 structural piles, 306 fender piles and 86 Operations Building piles.
The Ammunition Wharf was originally constructed using precast concrete piles. As a result of the steam curing process used at that time, an unknown quantity of piling is susceptible to a potentially catastrophic condition called Delayed Ettringite Formation (DEF). DEF is a result of high early temperatures in the concrete, which prevents the normal formation of ettringite. DEF occurs rapidly and without warning
Wharf was originally constructed using precast concrete piles. As a result of the steam curing process used at that time, an unknown quantity of piling is susceptible to a potentially catastrophic condition called Delayed Ettringite Formation (DEF). DEF is a result of high early temperatures in the concrete, which prevents the normal formation of ettringite. DEF occurs rapidly and without warning.
The Navy schedules inspections on waterfront facilities that usually occur every 3 years, but due to DEF at the Ammunition Wharf, inspections for that structure occur every two years. Based on the most recent inspection in 2021, there are 161 piles (158 under Ammunition Pier and three under the Operations Building at Ammunition Wharf) with some appreciable level of DEF damage (most or all of those piles will be replaced). More piles with DEF damage may be detected and therefore may need to be replaced over the duration of the LOA.
Table 1 shows the details of the proposed construction activities which are described below in greater detail.
Table 1—Project Components for Pile Replacement for the Ammunition Wharf Wharf structure (in-water construction) Construction details Total Piles Up to 118 piles installed over 5 years (including up to eight steel piles, with the remainder concrete). Quantity of concrete piles (24-inch) Up to 22 per year over 5 years. Quantity of permanent steel piles (36-inch) Up to 2 per year (Maximum of 8) over 5 years (Currently no steel pile installation is planned, installation would depend on future pile inspections). Pile Removal Method Cutting. Pile Installation Method Jetting and impact driving of concrete piles; Vibratory and impact driving of steel piles. No simultaneous pile driving will occur. Quantity of piles above −30 feet MLLW All. Maximum number of piles driven per day (approximately) Two concrete piles per day. One steel pile per day. Total duration of impact pile driving No more than 45 minutes per day (mean = 10 minutes for concrete piles; 15 minutes for steel piles)
driving of concrete piles; Vibratory and impact driving of steel piles. No simultaneous pile driving will occur. Quantity of piles above −30 feet MLLW All. Maximum number of piles driven per day (approximately) Two concrete piles per day. One steel pile per day. Total duration of impact pile driving No more than 45 minutes per day (mean = 10 minutes for concrete piles; 15 minutes for steel piles). Maximum duration of vibratory pile driving No more than 30 minutes (mean = 10 minutes per steel pile). Marine Construction Duration (including in-water restrictions) 3.5 months per year (In water work window: October 1-January 15). Removal of Existing Piles
After demolition of the deck portions of the wharf located above the waterline, three methods of pile removal (cutting/chipping, clamshell removal, and direct pull) may be used. However, hydraulic cutting will be the primary method of pile removal due to working under the wharf and the DEF damage to the piles. In some cases, piles may be cut at or below the mudline, with the below-mudline portion of the pile left in place. None of these pile removal activities are anticipated to result in take of marine mammals; therefore, they are not discussed further beyond the brief elaboration on jetting and pile cutting provided below.
Pile Installation
Three methods of pile installation for concrete and steel piles may be used (vibratory, jetting, and impact) depending on the type of pile and site conditions. Only one pile will be installed at a time; no simultaneous pile driving will occur. These methods are described below.
The primary methods of concrete pile installation would be water jetting to within 3 meters (m) of final depth and then impact pile driving to set or proof the final 3 m. Water jetting aids the penetration of a pile into a dense sand or sandy gravel stratum. Water jetting utilizes a carefully directed and pressurized flow of water at the pile tip, which disturbs a ring of soils directly beneath it
The primary methods of concrete pile installation would be water jetting to within 3 meters (m) of final depth and then impact pile driving to set or proof the final 3 m. Water jetting aids the penetration of a pile into a dense sand or sandy gravel stratum. Water jetting utilizes a carefully directed and pressurized flow of water at the pile tip, which disturbs a ring of soils directly beneath it. The jetting technique liquefies the soils at the pile tip during pile placement, reducing the friction and interlocking between adjacent sub grade soil particles around the water jet. For load-bearing structures, an impact hammer is typically required to strike a pile a number of times to ensure it has met the load-bearing specifications; this is referred to as “proofing.” Load-bearing piles installed with water jetting would still need to be proofed with an impact pile driver.
A vibratory hammer may be used to install the structural steel piles and fender piles. The primary method of pile installation for steel piles would be vibratory to within 3 m of final depth and then impact pile driving to set or proof the final 3 m. The vibratory pile driver method is a technique that may be used in pile installation where the substrate allows. Use of this technique may be limited in very hard substrates. This process begins by placing a choker cable around a pile and lifting it into vertical position with a crane. The pile is then lowered into position and set in place at the mudline. The pile is held steady while the vibratory driver installs the pile to the required tip elevation. In some substrates, a vibratory driver may be unable to advance a pile until it reaches the required depth. In these cases, an impact hammer may be used to advance the pile to the required depth.
Impact hammers may be used to proof concrete piles that have been jetted to depth or steel piles that have been driven using the vibratory method
driver installs the pile to the required tip elevation. In some substrates, a vibratory driver may be unable to advance a pile until it reaches the required depth. In these cases, an impact hammer may be used to advance the pile to the required depth.
Impact hammers may be used to proof concrete piles that have been jetted to depth or steel piles that have been driven using the vibratory method. Proofing involves impact pile driving to determine if the pile has been driven to the proper load-bearing specifications within the substrate. Proofing of concrete piles at the Ammunition Wharf in 2015 and 2016 required 200-600 strikes per pile to complete (Navy, 2016).
Impact hammers have a heavy piston that moves up and down striking the top of the pile and driving the pile into the substrate from the downward force of the hammer. Impact hammer pile proofing can typically take a minute or less to 30 minutes depending on pile type, pile size, and conditions ( i.e., bedrock, loose soils, etc. ) to reach the required tip elevation.
The Navy states that piles will be advanced to the extent practicable with a vibratory driver and only impact driven when required for proofing or when a pile cannot be advanced with a vibratory driver due to hard substrate conditions.
Existing piles that are structurally sound may require additional repair activities. Such activities could include wetwell repair; recoating of piles and mooring fittings; installation or replacement of passive cathode protection systems; repair and replacement of pile caps; concrete repair; mooring foundation and substructure repair; replacement of components ( e.g. hand rails, safety ladders, light poles); and rewrapping or replacement of steel cable straps on dolphins. These repairs are described in greater detail in the Navy's application but would not result in the take of marine mammals and are not discussed further
systems; repair and replacement of pile caps; concrete repair; mooring foundation and substructure repair; replacement of components ( e.g. hand rails, safety ladders, light poles); and rewrapping or replacement of steel cable straps on dolphins. These repairs are described in greater detail in the Navy's application but would not result in the take of marine mammals and are not discussed further.
Operation of the following equipment types is not reasonably expected to result in take of marine mammals and will not be discussed further beyond the brief summaries provided below:
• Jetting produces much lower sound levels (approximately 147.5 decibel (dB) Root Mean Square (RMS); NAVFAC SW, 2020) than vibratory pile driving 166 dB RMS (Navy, 2015). The sounds produced by jetting are of similar frequencies to the sounds produced by vessels, and are anticipated to diminish to background noise levels (or be masked by background noise levels) in Port Townsend Bay.
• Hydraulic cutting would be used be used to assist with removal of piles. Similar to jetting, the sounds produced by cutting are of similar frequencies to the sounds produced by vessels (NAVFAC SW, 2020), and are anticipated to diminish to background noise levels (or be masked by
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
To characterize potential species occurrence, the Navy's application utilized density information available for Puget Sound, and recent research and survey information conducted on-site or in Puget Sound
easures 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
To characterize potential species occurrence, the Navy's application utilized density information available for Puget Sound, and recent research and survey information conducted on-site or in Puget Sound. The Navy also discussed species occurrence with local species experts and reviewed incidental sighting reports from the Orca Network (Whidbey Island, WA) and Center for Whale Research (Friday Harbor, WA) for verified or reasonably verified species presence, as well as information on seasonal, intermittent, or unusual species occurrences.
Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history of the potentially affected species. NMFS fully considered all of this information, and we refer the reader to these descriptions instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS' website ( https://www.fisheries.noaa.gov/find-species ).
Table 2 lists all species or stocks for which take is expected and proposed to be authorized for this activity, and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. PBR is defined by the MMPA as the maximum number of 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)
ulation or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS' SARs). While no serious injury or mortality is expected to occur, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All stocks managed under the MMPA in this region are assessed in NMFS' U.S. Pacific Marine Mammal Stock Assessment Report. All values presented in Table 2 are the most recent available at the time of publication and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.
Table 2—Marine Mammal Species 4 Likely To Occur Near the Project Area That May Be Taken by the Navy's Activities 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 Artiodactyla—Cetacea—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): Humpback Whale Megaptera novaeangliae Central America/Southern Mexico-California-Oregon-Washington E, D, Y 1,496 (0.171, 1,284, 2021) 3.5 14.9 Mainland Mexico-California-Oregon-W
Annual M/SI 3 Order Artiodactyla—Cetacea—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): Humpback Whale Megaptera novaeangliae Central America/Southern Mexico-California-Oregon-Washington E, D, Y 1,496 (0.171, 1,284, 2021) 3.5 14.9 Mainland Mexico-California-Oregon-Washington T, D, Y 3,477 (0.101, 3,185, 2018) 43 22 Hawaii -, -, N 11,278 (0.56, 7,265, 2020) 127 27.09 Minke Whale Balaenoptera acutorostrata CA/OR/WA -, -, N 915 (0.792, 509, 2018) 4.1 ≥0.59 Odontoceti (toothed whales, dolphins, and porpoises) Family Phocoenidae (porpoises): Dall's Porpoise Phocoenoides dalli CA/OR/WA -, -, N 16,498 (0.61, 10,286, 2019) 99 ≥0.66 Harbor Porpoise Phocoena phocoena Washington Inland Waters -, -, N 11,233 (0.37, 8,308, 2015) 66 ≥7.2 Family Delphinidae: Killer Whale Orcinus orca West Coast Transient -, -, N 349 (N/A, 349, 2018) 3.5 0.4 Eastern North Pacific Southern Resident E, D, Y 74 (N/A, 74, 2021) 0.13 ≥0.4 Order Carnivora—Pinnipedia Family Otariidae (eared seals and sea lions): CA Sea Lion Zalophus californianus U.S -, -, N 257,606 (N/A,233,515, 2014) 14011 >320 Steller Sea Lion Eumetopias jubatus Eastern -, -, N 43,201 (N/A, 43,201, 2017) 2,592 112 Family Phocidae (earless seals): Harbor Seal Phoca vitulina Washington Northern Inland Waters -, -, N 11,036 5 (UNK, UNK, 1999) UND 9.8 Northern Elephant Seal Mirounga angustirostris CA Breeding -, -, N 187,386 (NA, 85,369, 2013) 5122 13.7 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
ies Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 3 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. 4 Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy ( https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)). 5 The abundance estimate for this stock is greater than 8 years old and is therefore not considered current. PBR is considered undetermined for this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available information for use in this document. As indicated above, all nine species (with nine managed stocks) in Table 2 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur
s stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available information for use in this document. As indicated above, all nine species (with nine managed stocks) in Table 2 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur. However, no take is proposed for authorization for killer whales and humpback whales for the reasons provided below.
Southern resident killer whales do occur occasionally in the waters north of NAVMAG Indian Island although as of June 2023 they have not been reported near Port Townsend since December 2020 and then only by hydrophones so the exact locations are unknown (Orca Network, 2023). It is unlikely any would occur close to the Ammunition Wharf. Occurrence in the inland waters are low in the winter through early spring (Orca Network, 2023), when project activities would occur. While critical habitat has been designated in Puget Sound for southern resident killer whales, the designation does not include the Port Townsend/Indian Island/Walan Point naval restricted area which extends out 500 m from the Ammunition Wharf (73 FR 78633; December 23, 2008). In contrast to southern resident killer whales, which exclusively prey on fish, the main diet of transient killer whales consists of marine mammals. Within Puget Sound, transient killer whales primarily hunt pinnipeds and porpoises, though some groups will occasionally target larger whales. The seasonal movements of transients are largely unpredictable, although there is a tendency to investigate harbor seal haulouts off Vancouver Island more frequently during the pupping season in August and September (Baird, 1994; Ford, 2014)
marine mammals. Within Puget Sound, transient killer whales primarily hunt pinnipeds and porpoises, though some groups will occasionally target larger whales. The seasonal movements of transients are largely unpredictable, although there is a tendency to investigate harbor seal haulouts off Vancouver Island more frequently during the pupping season in August and September (Baird, 1994; Ford, 2014). The movements and locations of southern resident killer whales are tracked daily by the Center for Whale Research and the Orca Network, therefore, exposures to noise from pile driving can be avoided if southern resident killer whales are known to be near the project area.
Similarly, humpback whales are considered to be regular, but not frequent visitors to Puget Sound, especially south of Admiralty Inlet. Opportunistic sightings primarily occur April through July in Puget Sound, although sightings have been reported in every month of the year. In addition to the timing of the planned activity, which minimizes potential for occurrence of humpback and killer whales, the Navy proposes to implement shutdown procedures for all cetaceans as needed to avoid harassment. For highly visible species, such as large whales, this is expected to be successful in avoiding any potential for take. No take of these species is anticipated or proposed for authorization, and we do not discuss them further.
Gray Whale
Two North Pacific populations of gray whales are formally recognized: the Western Pacific subpopulation (also known as the Western North Pacific or the Korean-Okhotsk population) (WNP) that is critically endangered and the Eastern Pacific population (also known as the Eastern North Pacific or the California-Chukchi population) (ENP) that appears to have recovered from exploitation and was removed from listing under the ESA in 1994 (Carretta et al., 2016)
recognized: the Western Pacific subpopulation (also known as the Western North Pacific or the Korean-Okhotsk population) (WNP) that is critically endangered and the Eastern Pacific population (also known as the Eastern North Pacific or the California-Chukchi population) (ENP) that appears to have recovered from exploitation and was removed from listing under the ESA in 1994 (Carretta et al., 2016). The two populations have historically been considered geographically isolated from each other; however, data from satellite-tracked whales indicate that there is some overlap between the stocks. Two WNP whales were tracked from Russian foraging areas along the Pacific rim to Baja California (Mate et al., 2011), and, in one case where the satellite tag remained attached to the whale for a longer period, a WNP whale was tracked from Russia to Mexico and back again (International Whaling Commission [IWC, 2012]). Between 22-24 WNP whales are known to have occurred in the eastern Pacific through comparisons of ENP and WNP photo-identification catalogs (IWC, 2012; Weller et al., 2012; Burdin et al., 2011). Urban et al. (2013) compared catalogs of photo-identified individuals from Mexico with photographs of whales off Russia and reported a total of 21 matches. Therefore, a portion of the WNP population is assumed to migrate, at least in some years, to the eastern Pacific during the winter breeding season. However, it is extremely unlikely that a gray whale in close proximity to NAVMAG Indian Island construction activity would be one of the few WNP whales that have been documented in the eastern Pacific. The likelihood that a WNP whale would be present in the vicinity of the proposed project is insignificant and discountable, and WNP gray whales are omitted from further analysis.
Eastern gray whales, however, are known to migrate along the U.S. West Coast on both their northward and southward migrations
activity would be one of the few WNP whales that have been documented in the eastern Pacific. The likelihood that a WNP whale would be present in the vicinity of the proposed project is insignificant and discountable, and WNP gray whales are omitted from further analysis.
Eastern gray whales, however, are known to migrate along the U.S. West Coast on both their northward and southward migrations. As the majority of gray whales migrate past the Strait of Juan de Fuca in route to or from their feeding or breeding grounds, a few of them enter Washington inland waters to feed (Stout et al., 2001; Calambodkidis et al., 2015). Gray whales are observed in Washington inland waters, including Puget Sound in all months of the year (Calambokidis et al., 2010; Orca Network, 2023) with peak numbers from March through June (Calambokidis et al., 2010, 2015). Fewer than 20 gray whales are documented in the inland waters of Washington and British Columbia each year beginning in et al., 2010). Gray whales feed on benthic invertebrates, including dense aggregations of ghost shrimp and tubeworms (Weitkamp et al., 1992, Richardson, 1997).
Gray whales that are not identified with the regularly occurring group in the Whidbey Island and Camano Island area are occasionally sighted in Puget Sound. These whales are not associated with feeding areas and are often emaciated (WDFW, 2012). Gray whales are expected to occur in the waters surrounding NAVMAG Indian Island. They are expected to occur primarily from March through June when in-water construction work will not occur. Therefore, some exposure to individual gray whales could occur over the duration of the project; however, project timing will help to minimize potential exposures.
Minke Whale
Minke whales from California to Washington appear to be behaviorally distinct from migratory whales further north ( i.e., Alaska stock). Animals from the California, Oregon, and Washington stock, including Washington inland waters are considered “resident”
al gray whales could occur over the duration of the project; however, project timing will help to minimize potential exposures.
Minke Whale
Minke whales from California to Washington appear to be behaviorally distinct from migratory whales further north ( i.e., Alaska stock). Animals from the California, Oregon, and Washington stock, including Washington inland waters are considered “resident”. Minke whales appear to establish home ranges in the inland waters of Washington (Dorsey, 1983; Dorsey et al., 1990). They are reported in the inland waters year-round, although the majority of the records are from March through November (Calambokidis & Baird, 1994). Minke whales are sighted primarily in the San Juan Islands and Strait of Juan de Fuca but are relatively rare in Puget Sound south of Admiralty Inlet (Orca Network, 2023). In the Strait of Juan de Fuca, individuals move within and between specific feeding areas around submarine banks (Stern et al., 1990). Dorsey et al. (1990) noted minke whales feeding in locations of strong tidal currents. Hoelzel et al. 16 (1989) reported that 80 percent of feeding observations in the San Juan Islands were over submarine slopes of moderate incline at a depth of about 20 m to 100 m. Three feeding grounds have been identified in the Strait of Juan de Fuca and San Juan Islands area (Osborne et al., 1988; Hoelzel et al., 1989; Dorsey et al., 1990; Stern et al., 1990). There is year-to-year variation in the use of these feeding areas, and other feeding areas probably exist (Osborne et al., 1988; Dorsey et al., 1990). A review of Washington inland water sighting data from January 2005 through August 2012 indicates that Minke whales typically occur as lone individuals or in small groups of two or three (Orca Network, 2023).
No minke whales have been reported in Port Townsend Bay although they have been reported in the Strait of Juan de Fuca and north of Port Townsend and along the western side of Whidbey Island near Smith Island in October (Orca Network, 2023)
rom January 2005 through August 2012 indicates that Minke whales typically occur as lone individuals or in small groups of two or three (Orca Network, 2023).
No minke whales have been reported in Port Townsend Bay although they have been reported in the Strait of Juan de Fuca and north of Port Townsend and along the western side of Whidbey Island near Smith Island in October (Orca Network, 2023).
Based on the information presented, the number of minke whales potentially present near NAVMAG Indian Island is expected to be very low in October and unlikely from November through February (Orca Network, 2023).
Dall's Porpoise
Dall's porpoise is one of the most common odontocete species in North Pacific waters (Jefferson, 1991; 2 Ferrero & Walker, 1999; Calambokidis & Barlow, 2004; Williams & Thomas, 2007). Dall's porpoise is found from northern Baja California, Mexico, north to the northern Bering Sea and south to southern Japan (Jefferson et al., 1993). However, the species is only common between 32° N lat. and 62° N lat. in the eastern North Pacific (Morejohn, 1979; Houck & Jefferson, 1999). Dall's porpoise are found in outer continental shelf, slope, and oceanic waters, typically in temperatures less than 17 °C (Houck & Jefferson, 1999; Reeves et al., 2002; Jefferson et al., 2015).
Dall's porpoises may occur in Washington inland waters year-round, but appear to be very rare (Evenson et al., 2016). Extensive aerial surveys conducted in Puget Sound and Hood Canal in all seasons from 2013-2015 logged only one sighting of one individual (Jefferson et al., 2016). Only four Dall's porpoise were detected in aerial surveys of the northern inland waters of Washington (Strait of Juan de Fuca, San Juan Islands, Strait of Georgia) during spring 2015 (Smultea et al., 2015). Additional sightings have been reported in the Strait of Juan de Fuca and Haro Strait between San Juan Island and Vancouver Island (Nysewander et al., 2005; Orca Network, 2023)
n et al., 2016). Only four Dall's porpoise were detected in aerial surveys of the northern inland waters of Washington (Strait of Juan de Fuca, San Juan Islands, Strait of Georgia) during spring 2015 (Smultea et al., 2015). Additional sightings have been reported in the Strait of Juan de Fuca and Haro Strait between San Juan Island and Vancouver Island (Nysewander et al., 2005; Orca Network, 2023). Tagging studies suggest Dall's porpoises seasonally move between the Haro Strait area and the Strait of Juan de Fuca or farther west (Hanson et al., 1998).
Dall's porpoise were detected in Puget Sound during aerial surveys in winter (1993-2008) and summer (1992-1999) (Nysewander et al., 2005; WDFW, 2008), with additional observations reported to Orca Network (2023). During the surveys, Dall's porpoise were sighted in Puget Sound as far south as Carr Inlet in southern Puget Sound and as far north as Saratoga Passage, north of Naval Station (NAVSTA) Everett (Nysewander et al., 2005; WDFW, 2008). Recent extensive aerial surveys of Puget Sound and Hood Canal during 2013-2015 detected only one individual (Jefferson et al., 2016), but did not specify its location. The number of Dall's porpoises potentially present near NAVMAG Indian Island is expected to be very low in any month.
Harbor Porpoise
In Washington inland waters, harbor porpoise are known to occur in the Strait of Juan de Fuca and the San Juan Islands area year-round (Calambokidis and Baird, 1994; Osmek et al., 1996; Carretta et al., 2012). Harbor porpoises were historically one of the most commonly observed marine mammals in Puget Sound (Scheffer and Slipp, 1948); however, there was a significant decline in sightings beginning in the 1940s (Everitt et al., 1979; Calambokidis et al., 1992)
in the Strait of Juan de Fuca and the San Juan Islands area year-round (Calambokidis and Baird, 1994; Osmek et al., 1996; Carretta et al., 2012). Harbor porpoises were historically one of the most commonly observed marine mammals in Puget Sound (Scheffer and Slipp, 1948); however, there was a significant decline in sightings beginning in the 1940s (Everitt et al., 1979; Calambokidis et al., 1992). Only a few sightings were reported between the 1970s and 1980s (Calambokidis et al., 1992; Osmek et al., 1996; Raum-Suryan and Harvey, 1998), and no harbor porpoise sightings were recorded during multiple ship and aerial surveys conducted in Puget Sound (including Hood Canal) in 1991 and 1994 (Calambokidis et al., 1992; Osmek et al., 1996).
Incidental sightings of marine mammals during aerial bird surveys conducted as part of the Puget Sound Ambient Monitoring Program (PSAMP) detected few harbor porpoises in Puget Sound between 1992 and 1999 (Nysewander et al., 2005). However, these sightings may have been negatively biased due to the low elevation of the plane, which may have caused an avoidance behavior. Since 1999, PSAMP data, stranding data, and aerial surveys conducted from 2013 to 2016 documented increasing numbers of harbor porpoise in Puget Sound, indicating that the species is increasing in the area (Nysewander, 2008; WDFW, 2008; Jeffries, 2013; Smultea et al., 2017).
Little information is available on harbor porpoise occurrence outside of Hood Canal and no site-specific information is available for NAVMAG Indian Island. No harbor porpoises have been reported in Port Townsend Bay although they have been reported just north of Port Townsend and along Marrowstone Island as they move south into Puget Sound (Orca Network, 2023). Based on the information presented, the number of harbor porpoises present near
California Sea Lion
During the summer, California sea lions breed on islands from the Gulf of California to the Channel Islands and forage in the Southern California Bight
hough they have been reported just north of Port Townsend and along Marrowstone Island as they move south into Puget Sound (Orca Network, 2023). Based on the information presented, the number of harbor porpoises present near
California Sea Lion
During the summer, California sea lions breed on islands from the Gulf of California to the Channel Islands and forage in the Southern California Bight. The primary rookeries are located on the California Channel Islands of San Miguel, San Nicolas, Santa Barbara, and San Clemente. In the nonbreeding season, adult and subadult males migrate northward along the coast to central and northern California, Oregon, Washington, and Vancouver Island, and return south in the spring (DeLong et al., 2017; Weise and Harvey, 2008). Primarily male California sea lions migrate into northwest waters with most adult females with pups remaining in waters near their breeding rookeries off the coasts of California and Mexico (Melin et al., 2000; Lowry and Maravilla-Chavez, 2005; Kuhns and Costa., 2014; Lowry et al., 2017). California sea lions also enter bays, harbors, and river mouths and often haul out on artificial structures such as piers, jetties, offshore buoys, and oil platforms.
Jeffries et al. (2000) and Jeffries (2012 personal communication) identified dedicated, regular haulouts used by adult and sub-adult California sea lions in Washington inland waters (See Figure 4-1 in the Navy's application). California sea lions are typically present most of the year except for mid-June through July in Washington inland waters, with peak abundance between October and May (NMFS, 1997; Jeffries et al., 2000). California sea lions would be expected to forage within the area, following local prey availability.
Steller Sea Lion
The eastern stock of Steller sea lions is found along the coasts of southeast Alaska to northern California where they occur at rookeries and numerous haulout locations along the coastline (Jeffries et al., 2000; Scordino, 2006)
ober and May (NMFS, 1997; Jeffries et al., 2000). California sea lions would be expected to forage within the area, following local prey availability.
Steller Sea Lion
The eastern stock of Steller sea lions is found along the coasts of southeast Alaska to northern California where they occur at rookeries and numerous haulout locations along the coastline (Jeffries et al., 2000; Scordino, 2006). Male Steller sea lions often disperse widely outside of the breeding season from breeding rookeries in northern California ( e.g., St. George Reef) and southern Oregon ( e.g., Rogue Reef) (Scordino, 2006; Wright et al., 2010). Based on mark recapture sighting studies, males migrate back into these Oregon and California locations from winter feeding areas in Washington, British Columbia, and Alaska (Scordino, 2006).
In Washington, Steller sea lions use haulout sites primarily along the outer coast from the Columbia River to Cape Flattery, as well as along the Vancouver Island side of the Strait of Juan de Fuca (Jeffries et al., 2000). A major winter haulout is located in the Strait of Juan de Fuca at Race Rocks, British Columbia, Canada (Canadian side of the Strait of Juan de Fuca) (Edgell & Demarchi, 2012). Numbers vary seasonally in Washington with peak numbers present during the fall and winter months and a decline in the summer months that corresponds to the breeding season at coastal rookeries (approximately late May to early June) (Jeffries et al., 2000). In Puget Sound, Jeffries (2012 personal communication) identified five winter haulout sites used by adult and subadult (immature or pre-breeding animals) Steller sea lions, ranging from immediately south of Port Townsend (near Admiralty Inlet) to Olympia in southern Puget Sound (see Figure 4-1 in the Navy's application). Numbers of animals observed at these sites ranged from a few to less than 100 (Jeffries, 2012 personal communication)
communication) identified five winter haulout sites used by adult and subadult (immature or pre-breeding animals) Steller sea lions, ranging from immediately south of Port Townsend (near Admiralty Inlet) to Olympia in southern Puget Sound (see Figure 4-1 in the Navy's application). Numbers of animals observed at these sites ranged from a few to less than 100 (Jeffries, 2012 personal communication). In addition, Steller sea lions opportunistically haul out on various navigational buoys in Admiralty Inlet south through southern Puget Sound near Olympia (Jeffries, 2012 personal communication). One or two animals occur on these buoys.
No haulouts are known in the immediate vicinity of NAVMAG Indian Island; therefore, no shore-based surveys have been conducted there and no opportunistic sightings have been reported. The nearest Steller sea lion haul-outs to NAVMAG Indian Island is located on the east side of Marrowstone Island, approximately 7 km away (Figure 4-1 in the Navy's application). Monitoring during pile driving in 2015 and 2016 did not observe any Steller sea lions hauled out on the Port Security Barrier or swimming through the area (Navy, 2014, 2016, 2021). Therefore, Steller sea lions are expected to be rare in the waters off NAVMAG Indian Island.
Northern Elephant Seal
The northern elephant seal occurs almost exclusively in the eastern and central North Pacific. Rookeries are located from central Baja California, Mexico, to northern California (Stewart & Huber, 1993). Adult elephant seals engage in two long migrations per year, one following the breeding season, and another following the annual molt (Stewart and DeLong, 1995; Robinson et al., 2012). Between the two foraging periods they return to land to molt with females returning earlier than males (March through April versus July through August). After the molt, adults then return to their northern feeding areas until the next winter breeding season. Breeding occurs from December to March (Stewart & Huber, 1993)
r following the annual molt (Stewart and DeLong, 1995; Robinson et al., 2012). Between the two foraging periods they return to land to molt with females returning earlier than males (March through April versus July through August). After the molt, adults then return to their northern feeding areas until the next winter breeding season. Breeding occurs from December to March (Stewart & Huber, 1993). Juvenile elephant seals typically leave the rookeries in April or May and head north, traveling an average of 900 to 1,000 km. Most elephant seals return to their natal rookeries when they start breeding (Huber et al., 1991). Their foraging range extends thousands of miles offshore into the central North Pacific. Adults tend to stay offshore, but juveniles and subadults are often seen along the coasts of Oregon, Washington, and British Columbia (Condit & Le Boeuf, 1984; Stewart & Huber, 1993).
In Washington inland waters, there are regular haulout sites in the Strait of Juan de Fuca at Smith and Minor Islands, Dungeness Spit, and Protection Island that are thought to be used year-round (Jeffries et al., 2000; Jeffries, 2012 personal communication) (Figure 4-1 in the Navy's application). Pupping has occurred at these sites, as well as Race Rocks on the British Columbia side of the Strait of Juan de Fuca (Jeffries, 2012 personal communication).
No haulouts occur in Puget Sound with the exception of individual elephant seals occasionally hauling out for 2 to 4 weeks to molt, usually during the spring and summer and typically on sandy beaches (Calambokidis & Baird, 1994). These animals are usually yearlings or subadults and their haulout locations are unpredictable. Although regular haul-outs occur in the Strait of Juan de Fuca, the occurrence of elephant seals in Puget Sound is unpredictable and rare.
Pacific Harbor Seal
Harbor seals are a coastal species, rarely found more than 21 km from shore, and frequently occupy bays, estuaries, and inlets (Baird, 2001)
These animals are usually yearlings or subadults and their haulout locations are unpredictable. Although regular haul-outs occur in the Strait of Juan de Fuca, the occurrence of elephant seals in Puget Sound is unpredictable and rare.
Pacific Harbor Seal
Harbor seals are a coastal species, rarely found more than 21 km from shore, and frequently occupy bays, estuaries, and inlets (Baird, 2001). Individual seals have been observed several kilometers upstream in coastal rivers (Baird, 2001). Ideal harbor seal habitat includes haul-out sites, shelter during the breeding periods, and sufficient food (Bjørge, 2002). Harbor seals generally do not make extensive pelagic migrations ( i.e., less than 50 km; Baird, 2001), Harbor seals have also displayed strong fidelity to haul-out sites.
Harbor seals are the most common, widely distributed marine mammal found in Washington marine waters and are frequently observed in the nearshore marine environment. They occur year-round and breed in Washington. Numerous harbor seal haulouts occur in Washington inland waters (Figure 4-1 in the Navy's application). Haulouts include intertidal and subtidal rock outcrops, beaches, reefs, sandbars, log et al., 2000). Harbor seals are expected to occur year-round, the nearest documented haul-out to NAVMAG Indian Island is Rat Island at the north end of NAVMAG Indian Island approximately 2.4 km from the Ammunition Wharf. The haulout at Rat Island is estimated to have less than 100 individuals (Jeffries, 2012 personal communication).
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al
ater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling, etc. ). Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 3.
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
orhynchid, 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.
Potential Effects of Specified Activities on Marine Mammals and Their Habitat
This section provides a discussion of the ways in which components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and whether those impacts are reasonably expected to, or reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival
rs the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and whether those impacts are reasonably expected to, or reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.
Acoustic effects on marine mammals during the specified activities can occur from impact pile driving and vibratory driving and removal. The effects of underwater noise from the Navy's proposed activities have the potential to result in Level A or Level B harassment of marine mammals in the action areas.
Description of Sound Sources
The marine soundscape is comprised of both ambient and anthropogenic sounds. Ambient sound is defined as the all-encompassing sound in a given place and is usually a composite of sound from many sources both near and far (American National Standards Institute [ANSI], 1995). The sound level of an area is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical ( e.g., waves, wind, precipitation, earthquakes, ice, atmospheric sound), biological ( e.g., sounds produced by marine mammals, fish, and invertebrates), and anthropogenic sound ( e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at any given location and time—which comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and shipping activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent
hich comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and shipping activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 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 activities may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals.
In-water construction activities associated with the projects would include impact and vibratory pile installation and vibratory removal. The sounds produced by these activities fall into one of two general sound types: impulsive and non-impulsive. Impulsive sounds ( e.g., explosions, e.g., machinery operations such as drilling or dredging, vibratory pile driving, underwater chainsaws, and active sonar systems) can be broadband, narrowband or tonal, brief or prolonged (continuous or intermittent), and typically do not have the high peak sound pressure with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward 1997 in Southall et al., 2007).
Two types of hammers would be used on these projects, impact and vibratory. Impact hammers operate by repeatedly dropping and/or pushing a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is considered impulsive
they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward 1997 in Southall et al., 2007).
Two types of hammers would be used on these projects, impact and vibratory. Impact hammers operate by repeatedly dropping and/or pushing a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is considered impulsive. Vibratory hammers install piles by vibrating them and allowing the weight of the hammer to push them into the sediment. Vibratory hammers produce non-impulsive, continuous sounds. Vibratory hammering generally produces sound pressure levels (SPLs) 10 to 20 dB lower than impact pile driving of the same-sized pile (Oestman et al., 2009). Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time (Nedwell and Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of the Navy's proposed activities on marine mammals could be generated from both non-acoustic and acoustic stressors. Potential non-acoustic stressors include the physical presence of the equipment, vessels, and personnel; however, we expect that any animals that approach the project site(s) close enough to be harassed due to the presence of equipment or personnel would be within the Level B harassment zones from pile driving and would already be subject to harassment from the in-water activities. Therefore, any impacts to marine mammals are expected to primarily be acoustic in nature. Acoustic stressors are generated by heavy equipment operation during pile installation and removal ( i.e., impact and vibratory pile driving and removal).
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic environment from pile driving equipment is the primary means by which marine mammals may be harassed from the Navy's specified activities
marily be acoustic in nature. Acoustic stressors are generated by heavy equipment operation during pile installation and removal ( i.e., impact and vibratory pile driving and removal).
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic environment from pile driving equipment is the primary means by which marine mammals may be harassed from the Navy's specified activities. In general, animals exposed to natural or anthropogenic sound may experience physical and psychological effects, ranging in magnitude from none to severe (Southall et al., 2007). Generally, exposure to pile driving and removal and other construction noise has the potential to result in auditory threshold shifts and behavioral reactions ( e.g., avoidance, temporary cessation of foraging and vocalizing, changes in dive behavior). Exposure to anthropogenic noise can also lead to non-observable physiological responses such as an increase in stress hormones. Additional noise in a marine mammal's habitat can mask acoustic cues used by marine mammals to carry out daily functions such as communication and predator and prey detection. The effects of pile driving and demolition noise on marine mammals are dependent on several factors, including, but not limited to, sound type ( e.g., impulsive vs. non-impulsive), the species, age and sex class ( e.g., adult male vs. mother with calf), duration of exposure, the distance between the pile and the animal, received levels, behavior at time of exposure, and previous history with exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss physical auditory effects (threshold shifts) followed by behavioral effects and potential impacts on habitat. No physiological effects other than permanent threshold shift (PTS) (discussed below) are anticipated or proposed to be authorized, and therefore are not discussed further
at time of exposure, and previous history with exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss physical auditory effects (threshold shifts) followed by behavioral effects and potential impacts on habitat. No physiological effects other than permanent threshold shift (PTS) (discussed below) are anticipated or proposed to be authorized, and therefore are not discussed further.
NMFS defines a noise-induced threshold shift (TS) as a change, usually an increase, in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). The amount of threshold shift is customarily expressed in dB. A TS can be permanent or temporary. As described in NMFS (2018), there are numerous factors to consider when examining the consequence of TS, including, but not limited to, the signal temporal pattern ( e.g., impulsive or non-impulsive), likelihood an individual would be exposed for a long enough duration or to a high enough level to induce a TS, the magnitude of the TS, time to recovery (seconds to minutes or hours to days), the frequency range of the exposure ( i.e., spectral content), the hearing and vocalization frequency range of the exposed species relative to the signal's frequency spectrum ( i.e., how animal uses sound within the frequency band of the signal; e.g., Kastelein et al., 2014), and the overlap between the animal and the source ( e.g., spatial, temporal, and spectral).
Permanent Threshold Shift (PTS) —NMFS defines PTS as a permanent, irreversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Available data from humans and other terrestrial mammals indicate that a 40 dB TS approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson et al., 2008)
ible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Available data from humans and other terrestrial mammals indicate that a 40 dB TS approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson et al., 2008). PTS levels for marine mammals are estimates, because there are limited empirical data measuring PTS in marine mammals ( e.g., Kastak et al., 2008), largely due to the fact that, for various ethical reasons, experiments involving anthropogenic noise exposure at levels inducing PTS are not typically pursued or authorized (NMFS, 2018).
Temporary Threshold Shift (TTS) —A temporary, reversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). Based on data from cetacean TTS measurements (see Southall et al., 2007), a TTS of 6 dB is considered the minimum TS shift clearly larger than any day-to-day or session-to-session variation in a subject's normal hearing ability (Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in Finneran (2016), marine mammal studies have shown the amount of TTS increases with cumulative sound exposure level (SEL cum ) in an accelerating fashion: At low exposures with lower SEL cum , the amount of TTS is typically small and the growth curves have shallow slopes. At exposures with higher SEL cum , the growth curves become steeper and approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below)
h higher SEL cum , the growth curves become steeper and approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many et al., 2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without cost.
Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin, beluga whale ( Delphinapterus leucas ), harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis )) and five species of pinnipeds exposed to a limited number of sound sources ( i.e., mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). TTS was not observed in trained spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran, 2015). The potential for TTS from impact pile driving exists. After exposure to playbacks of impact pile driving sounds (rate 2,760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 minute exposure to 5 dB after 360 minute exposure; recovery occurred within 60 minutes (Kastelein et al., 2016). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. No data are available on noise-induced hearing loss for mysticetes
f impact pile driving sounds (rate 2,760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 minute exposure to 5 dB after 360 minute exposure; recovery occurred within 60 minutes (Kastelein et al., 2016). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. No data are available on noise-induced hearing loss for mysticetes. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall et al. (2007), Finneran and Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018).
The Navy proposes to use impact pile driving to install some piles for these projects. There would likely be pauses in activities producing the sound ( e.g., impact pile driving) during each day. Given these pauses and the fact that many marine mammals are likely moving through the project areas and not remaining for extended periods of time, the potential for TS declines.
Behavioral Harassment —Exposure to noise from pile driving and removal also has the potential to behaviorally disturb marine mammals. Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder, 2007; Weilgart, 2007; National Research Council [NRC], 2005)
ing a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder, 2007; Weilgart, 2007; National Research Council [NRC], 2005).
Disturbance may result in changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); or avoidance of areas where sound sources are located. Pinnipeds may increase their haulout time, possibly to avoid in-water disturbance (Thorson and Reyff, 2006). Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors ( e.g., species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors ( e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison et al., 2012), and can vary depending on characteristics associated with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). In general, pinnipeds seem more tolerant of, or at least habituate more quickly to, potentially disturbing underwater sound than do cetaceans, and generally seem to be less responsive to exposure to industrial sound than most cetaceans. Please see Appendices B and C of Southall et al
ted with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). In general, pinnipeds seem more tolerant of, or at least habituate more quickly to, potentially disturbing underwater sound than do cetaceans, and generally seem to be less responsive to exposure to industrial sound than most cetaceans. Please see Appendices B and C of Southall et al. (2007) for a review of studies involving marine mammal behavioral responses to sound.
Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance ( e.g., Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal.
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 (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
vioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses (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
ed. 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; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker, 2000; Romano et al., 2002b) and, more rarely, studied in wild populations ( e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as “distress.” In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003), however distress is an unlikely result of these projects based on observations of marine mammals during previous, similar projects in the area.
Masking —Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995)
n observations of marine mammals during previous, similar projects in the area.
Masking —Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., pile driving, shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest ( e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities ( e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Masking of natural sounds can result when human activities produce high levels of background sound at frequencies important to marine mammals. Conversely, if the background level of underwater sound is high ( e.g., on a day with strong wind and high waves), an anthropogenic sound source would not be detectable as far away as would be possible under quieter conditions and would itself be masked. The Puget Sound area contains active commercial shipping, ferry operations, and commercial fishing as well as numerous recreational and other commercial vessels, and background sound levels in the area are already elevated
day with strong wind and high waves), an anthropogenic sound source would not be detectable as far away as would be possible under quieter conditions and would itself be masked. The Puget Sound area contains active commercial shipping, ferry operations, and commercial fishing as well as numerous recreational and other commercial vessels, and background sound levels in the area are already elevated.
Airborne Acoustic Effects —Pinnipeds that occur near the project site could be exposed to airborne sounds associated with pile driving and removal that have the potential to cause behavioral harassment, depending on their distance from pile driving activities. Cetaceans are not expected to be exposed to airborne sounds that would result in harassment as defined under the MMPA.
Airborne noise would primarily be an issue for pinnipeds that are swimming or hauled out near the project site within the range of noise levels elevated above the acoustic criteria. We recognize that pinnipeds in the water could be exposed to airborne sound that may result in behavioral harassment when looking with their heads above water. Most likely, airborne sound would cause behavioral responses similar to those discussed above in relation to underwater sound. For instance, anthropogenic sound could cause hauled out pinnipeds to exhibit changes in their normal behavior, such as reduction in vocalizations, or cause them to temporarily abandon the area and move further from the source. However, these animals would likely previously have been taken because of exposure to underwater sound above the behavioral harassment thresholds, which are generally larger than those associated with airborne sound. There are no haulouts in close proximity to the project site. Thus, the behavioral harassment of these animals is already accounted for in these estimates of potential take
he source. However, these animals would likely previously have been taken because of exposure to underwater sound above the behavioral harassment thresholds, which are generally larger than those associated with airborne sound. There are no haulouts in close proximity to the project site. Thus, the behavioral harassment of these animals is already accounted for in these estimates of potential take. Therefore, we do not believe that authorization of incidental take resulting from airborne sound for pinnipeds is warranted, and airborne sound is not discussed further here.
Marine Mammal Habitat Effects
The Navy's proposed construction activities could have localized, temporary impacts on marine mammal habitat, including prey, by increasing in-water sound pressure levels and slightly decreasing water quality. Increased noise levels may affect acoustic habitat (see masking discussion above) and adversely affect marine mammal prey in the vicinity of the project areas (see discussion below). During impact and vibratory pile driving or removal, elevated levels of underwater noise would ensonify the project areas where both fishes and mammals occur and could affect foraging success. Additionally, marine mammals may avoid the area during construction, however, displacement due to noise is expected to be temporary and is not expected to result in long-term effects to the individuals or populations. Construction activities are of short duration and would likely have temporary impacts on marine mammal habitat through increases in underwater and airborne sound.
A temporary and localized increase in turbidity near the seafloor would occur in the immediate area surrounding the area where piles are installed or removed. In general, turbidity associated with pile installation is localized to about a 25-ft (7.6-m) radius around the pile (Everitt et al., 1980). The sediments of the project site will settle out rapidly when disturbed
water and airborne sound.
A temporary and localized increase in turbidity near the seafloor would occur in the immediate area surrounding the area where piles are installed or removed. In general, turbidity associated with pile installation is localized to about a 25-ft (7.6-m) radius around the pile (Everitt et al., 1980). The sediments of the project site will settle out rapidly when disturbed. Cetaceans are not expected to be close enough to the pile driving areas to experience effects of turbidity, and any pinnipeds could avoid localized areas of turbidity. Local currents are anticipated to disburse any additional suspended sediments produced by project activities at moderate to rapid rates depending on tidal stage. Therefore, we expect the impact from increased turbidity levels to be discountable to marine mammals and do not discuss it further.
In-Water Construction Effects on Potential Foraging Habitat —The area likely impacted by the project is relatively small compared to the available habitat in Port Townsend Bay and the larger Puget Sound. The area is highly influenced by anthropogenic activities. The total seafloor area affected by pile installation and removal is a small area compared to the vast foraging area available to marine mammals in the area. At best, the impact area provides marginal foraging habitat for marine mammals and fishes. Furthermore, pile driving and removal at the project site would not obstruct long-term movements or migration of marine mammals.
Avoidance by potential prey ( i.e., fish or, in the case of transient killer whales, other marine mammals) of the immediate area due to the temporary loss of this foraging habitat is also possible. The duration of fish and marine mammal avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated
f marine mammals.
Avoidance by potential prey ( i.e., fish or, in the case of transient killer whales, other marine mammals) of the immediate area due to the temporary loss of this foraging habitat is also possible. The duration of fish and marine mammal avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated. Any behavioral avoidance
In-Water Construction Effects on Potential Prey —Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., crustaceans, cephalopods, fish, zooplankton, other marine mammals). Marine mammal prey varies by species, season, and location. Here, we describe studies regarding the effects of noise on known marine mammal prey other than other marine mammals (which have been discussed earlier).
Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning ( e.g., Zelick and Mann, 1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.
Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution
impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.
Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation ( e.g., feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish; several are based on studies in support of large, multiyear bridge construction projects ( e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992). 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).
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
ed when damaged cells are replaced with new cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013).
The most likely impact to fishes from pile driving and removal and construction activities at the project areas would be temporary behavioral avoidance of the area. The duration of fish avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated.
Construction activities, in the form of increased turbidity, have the potential to adversely affect forage fish in the project areas. Forage fish form a significant prey base for many marine mammal species that occur in the project areas. Increased turbidity is expected to occur in the immediate vicinity (on the order of 10 ft (3 m) or less) of construction activities. However, suspended sediments and particulates are expected to dissipate quickly within a single tidal cycle. Given the limited area affected and high tidal dilution rates any effects on forage fish are expected to be minor or negligible. Finally, exposure to turbid waters from construction activities is not expected to be different from the current exposure; fish and marine mammals in the project area are routinely exposed to substantial levels of suspended sediment from natural and anthropogenic sources
Given the limited area affected and high tidal dilution rates any effects on forage fish are expected to be minor or negligible. Finally, exposure to turbid waters from construction activities is not expected to be different from the current exposure; fish and marine mammals in the project area are routinely exposed to substantial levels of suspended sediment from natural and anthropogenic sources.
In summary, given the brief and intermittent duration (24 days between October 1 and January 15) of sound associated with individual pile driving events and the relatively small areas being affected, pile driving activities associated with the proposed actions are not likely to have a permanent, adverse effect on any fish habitat, or populations of fish species. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. Thus, we conclude that impacts of the specified activities are not likely to have more than short-term adverse effects on any prey habitat or populations of prey species. Further, any impacts to marine mammal habitat are not expected to result in significant or long-term consequences for individual marine mammals, or to contribute to adverse impacts on their populations.
Estimated Take
This section provides an estimate of the number of incidental takes proposed for authorization through this proposed rule, which will inform both NMFS' consideration of “small numbers,” and the negligible impact determinations.
Harassment is the only type of take expected to result from these activities
marine mammals, or to contribute to adverse impacts on their populations.
Estimated Take
This section provides an estimate of the number of incidental takes proposed for authorization through this proposed rule, which will inform both NMFS' consideration of “small numbers,” and the negligible impact determinations.
Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use of the acoustic sources ( i.e., vibratory and impact pile driving equipment) has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for auditory injury (Level A harassment) to result, primarily for harbor seals (phocids) because these animals are known to occur in close proximity to the pile driving locations. Auditory injury is unlikely to occur for other hearing groups or species. The proposed mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is anticipated or proposed to be authorized for this activity. Below, we describe how the proposed take numbers are estimated
ving locations. Auditory injury is unlikely to occur for other hearing groups or species. The proposed mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is anticipated or proposed to be authorized for this activity. Below, we describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the e.g., previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the proposed take estimates.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment).
Level B Harassment —Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context ( e.g., frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment ( e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict ( e.g., Southall et al., 2007, 2021; Ellison et al., 2012)
ure context ( e.g., frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment ( e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict ( e.g., Southall et al., 2007, 2021; Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous ( e.g., vibratory pile-driving, drilling) and above RMS SPL 160 dB re 1 μPa for non-explosive impulsive ( e.g., seismic airguns) or intermittent ( e.g., scientific sonar) sources.
The Navy's proposed activity includes the use of continuous (vibratory hammer source type) and impulsive (impact hammer) sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1 μPa are applicable.
Level A Harassment —NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). The Navy's proposed activity includes the use of impulsive (impact hammer) and non-impulsive (vibratory hammer) sources.
These thresholds are provided in the Table 4 below
l criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). The Navy's proposed activity includes the use of impulsive (impact hammer) and non-impulsive (vibratory hammer) sources.
These thresholds are provided in the 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.
Table 4—Thresholds Identifying the Onset of Permanent Threshold Shift 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)
otential 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 are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient.
The sound field in the project area is the existing background noise plus additional construction noise from the proposed project. Marine mammals are expected to be affected by sound generated by the primary components of the project ( i.e., impact and vibratory pile driving).
Data from prior pile driving projects at the Naval Base Kitsap Bangor and Bremerton waterfronts were reviewed in the analysis. The representative sound pressure levels used in the analysis are presented in Table 5
tion noise from the proposed project. Marine mammals are expected to be affected by sound generated by the primary components of the project ( i.e., impact and vibratory pile driving).
Data from prior pile driving projects at the Naval Base Kitsap Bangor and Bremerton waterfronts were reviewed in the analysis. The representative sound pressure levels used in the analysis are presented in Table 5.
For vibratory pile driving distances to the PTS thresholds, the transmission loss (TL) model described above incorporated the auditory weighting functions for each hearing group using a single frequency as described in the NMFS Spreadsheet (NMFS, 2018). For impact pile driving distances to the PTS thresholds for 36-inch steel pile and 24-inch concrete pile, the TL model described above incorporated frequency weighting adjustments by applying the auditory weighting function over the entire 1-second SEL spectral data sets from impact pile driving. If a source level for a particular pile size was not available, the next highest source level was used to produce a conservative estimate of areas above threshold values.
In order to calculate distances to the Level A harassment and Level B harassment thresholds for the methods and piles being used in this project, the Navy used acoustic monitoring data from various similar locations to develop source levels for the different pile types, sizes, and methods proposed for use (Table 5).
Table 5—Source Levels for Proposed Removal and Installation Activities Pile diameter (inches) RMS 1 (dB re 1 µPa) Peak 1 (dB re 1 µPa) SEL 2 (dB re 1 µPa 2 sec) Impact Installation Concrete 24 174 189 167 Steel Pipe 2 36 192 211 184 Vibratory Removal Steel Fender 14 150 N/A N/A Vibratory Installation Steel Fender 14 150 N/A N/A Composite Fender 18.75 150 N/A N/A Steel pipe 36 167 N/A N/A Source: Navy, 2015; Navy, 2017, 2018, NAVFAC SW, 2020; WDOT, 2017. Key: N/A = not applicable; RMS = root mean square; SEL = sound exposure level
SEL 2 (dB re 1 µPa 2 sec) Impact Installation Concrete 24 174 189 167 Steel Pipe 2 36 192 211 184 Vibratory Removal Steel Fender 14 150 N/A N/A Vibratory Installation Steel Fender 14 150 N/A N/A Composite Fender 18.75 150 N/A N/A Steel pipe 36 167 N/A N/A Source: Navy, 2015; Navy, 2017, 2018, NAVFAC SW, 2020; WDOT, 2017. Key: N/A = not applicable; RMS = root mean square; SEL = sound exposure level. 1 Sound pressure levels are presented for a distance of 10 m from the pile. RMS and Peak levels are relative to 1 μPa and cumulative SEL levels are relative to 1 μPa 2 sec; and 2 Values modeled for impact driving 36-inch steel piles will be reduced by 8 dB for noise exposure modeling to account for attenuation from a bubble curtain. A bubble curtain will be used to minimize the noise generated by impact driving of steel pipe piles. Note that impact pile driving of steel piles would only occur if it is necessary to install the 36-inch steel piles and none are currently planned to be installed. If steel piles became necessary then a maximum of 2 piles would be installed within the 5-year effective period of the LOA. The bubble curtain is expected to attenuate impact pile driving sound levels an average of 8 dB based on past performance during similar Navy projects in Puget Sound (Navy, 2015); therefore, 8 dB was subtracted from values in Table 5 prior to modeling the behavioral and PTS thresholds for impact pile driving steel pipe piles. For the cumulative SEL PTS thresholds, auditory weighting functions were applied to the attenuated one-second SEL spectra for steel pipe piles.
Level B Harassment Zones
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
uditory weighting functions were applied to the attenuated one-second SEL spectra for steel pipe piles.
Level B Harassment Zones
TL is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is:
TL = B * Log10 (R1/R2), Where: TL = transmission loss in dB, B = transmission loss coefficient (for practical spreading equals 15), R1 = the distance of the modeled SPL from the driven pile, and R2 = the distance from the driven pile of the initial measurement. The recommended TL coefficient for most nearshore environments is the practical spreading value of 15. This value results in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions, which is the most appropriate assumption for the Navy' proposed activities. The Level B harassment zones and areas for the Navy's proposed activities are shown in Table 6.
Table 6—Calculated Radial Distance(s) to Underwater Marine Mammal Vibratory Pile Driving Noise Thresholds and Areas Encompassed Within Threshold Distance Type Behavioral disturbance—Level B harassment (120 dB RMS) Radial distance to threshold Area encompassed by threshold 14-inch steel H fender pile (vibratory) 1,000 m 1.8 km. 18.75-in composite fender pile (vibratory) 1,000 m 1.8 km. 36-inch steel (vibratory) 13.6 km 54 km. Level A Harassment Zones
The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes
ified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources such as impact and vibratory driving, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur PTS.
The isopleths generated by the User Spreadsheet used the same TL coefficient as the Level B harassment zone calculations ( i.e., the practical spreading value of 15). Inputs used in the User Spreadsheet ( e.g., number of piles per day, duration and/or strikes per pile) are presented in Table 7. The maximum RMS SPL/SEL SPL and resulting isopleths are reported below in Table 8 and Table 9. The maximum
Table 7— Parameters of Pile Driving Activity Used in User Spreadsheet 24-inch concrete 36-inch steel Fender pile Removal or installation of steel 14-inch steel or 18.75-inch composites 36-inch steel Type of installation/removal Impact Impact Vibratory Vibratory Vibratory. Source Level 167 SEL/189 PK 184 SEL/211 PK 144 RMS 150 RMS 192 RMS Weighting Factor Adjustment (kHz) 2 2 2.5 2.5 2.5. (a) Number of strikes/pile 1,000 500 (a) Activity Duration (min) within 24-h period 10 10 45. Propagation (xLogR) 15 15 15 15 15. Piles per day 2 1 2 2 1
l 14-inch steel or 18.75-inch composites 36-inch steel Type of installation/removal Impact Impact Vibratory Vibratory Vibratory. Source Level 167 SEL/189 PK 184 SEL/211 PK 144 RMS 150 RMS 192 RMS Weighting Factor Adjustment (kHz) 2 2 2.5 2.5 2.5. (a) Number of strikes/pile 1,000 500 (a) Activity Duration (min) within 24-h period 10 10 45. Propagation (xLogR) 15 15 15 15 15. Piles per day 2 1 2 2 1. Distance of source level measurement (meters) 10 10 10 10 10. Table 8—Calculated Radial Distance(s) to Impact Pile Driving Noise Thresholds for Level A and Level B Harassment and Associated Areas 1 Level A harassment pinnipeds Harbor seal Sea lion Level A harassment cetaceans LF MF HF Behavioral disturbance level B (160 dB RMS) Radial distance to threshold Area en

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