# Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to U.S. Navy Marine Structure Maintenance and Pile Replacement in Washington > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2018-04148 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** March 5, 2018 - **Citation:** 83 FR 9366 ## Text DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 218 [Docket No. 170919913-8186-01] RIN 0648-BH27 Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to U.S. Navy Marine Structure Maintenance and Pile Replacement in 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 conducting construction activities related to marine structure maintenance and pile replacement at facilities in Washington, over the course of five years (2018-2023). 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 April 4, 2018. ADDRESSES: You may submit comments on this document, identified by NOAA-NMFS-2018-0032, by any of the following methods: • Electronic submission: Submit all electronic public comments via the federal e-Rulemaking Portal. Go to www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2018-0032, click the “Comment Now!” icon, complete the required fields, and enter or attach your comments. • Mail: Submit written comments to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910. 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 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: Ben Laws, Office of Protected Resources, NMFS, (301) 427-8401. SUPPLEMENTARY INFORMATION: Availability A copy of the Navy's application and any supporting documents, as well as a list of the references cited in this document, may be obtained online at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. 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 would establish a framework under the authority of the MMPA (16 U.S.C. 1361 et seq. ) to allow for the authorization of take of marine mammals incidental to the Navy's construction activities related to marine structure maintenance and pile replacement at facilities in Washington. We received an application from the Navy requesting five-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 five 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 I provide the legal basis for issuing this proposed rule containing five-year regulations, and for any subsequent LOAs. As directed by this legal authority, this proposed rule contains mitigation, monitoring, and reporting requirements. Summary of Major Provisions Within the Proposed Rule Following is a summary of the major provisions of this proposed rule regarding Navy construction activities. These measures include: • Required 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. Background Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1361 et seq. ) directs the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made, regulations are issued, and notice is provided to the public. An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such 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. The MMPA states that the term “take” means to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal. 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 evaluate our proposed action ( i.e., the promulgation of regulations and subsequent issuance of incidental take authorization) and alternatives 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 NAO 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 proposed action qualifies to be categorically excluded from further NEPA review. Information in the Navy's application and this notice 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 prior to concluding our NEPA process or making a final decision on the request for incidental take authorization. Summary of Request On July 24, 2017, we received an adequate and complete request from the Navy requesting authorization for take of marine mammals incidental to construction activities related to marine structure maintenance and pile replacement at six Naval installations in Washington inland waters. On August 4, 2017 (82 FR 36359), we published a notice of receipt of the Navy's application in the Federal Register , requesting comments and information related to the request for thirty days. We received comments from Whale and Dolphin Conservation (WDC). The comments received from WDC were considered in development of this proposed rule and are available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. The Navy proposes to conduct construction necessary for maintenance of existing in-water structures at the following facilities: Naval Base Kitsap (NBK) Bangor, NBK Bremerton, NBK Keyport, NBK Manchester, Zelatched Point, and Naval Station Everett (NS Everett). These repairs would include use of impact and vibratory pile driving, including installation and removal of steel, concrete, plastic, and timber piles. Hereafter (unless otherwise specified or detailed) we use the term “pile driving” to refer to both pile installation and pile removal. The use of both vibratory and impact pile driving is expected to produce underwater sound at levels that have the potential to result in harassment of marine mammals. The Navy requests authorization to take individuals of 10 species by Level B harassment. Take by Level A harassment was requested only for the harbor seal. The proposed regulations would be valid for five years (2018-2023). Description of the Specified Activity Overview Maintaining existing wharfs and piers is vital to sustaining the Navy's mission and ensuring readiness. To ensure continuance of necessary missions at the six installations, the Navy must conduct annual maintenance and repair activities at existing marine waterfront structures, including removal and replacement of piles of various types and sizes. The Navy refers to this program as the Marine Structure Maintenance and Pile Replacement (MPR) program. Exact timing and amount of necessary in-water work is unknown, but the Navy estimates replacing up to 822 structurally unsound piles over the 5-year period, including individual actions currently planned and estimates for future marine structure repairs. Construction will include use of impact and vibratory pile driving, including removal and installation of steel, concrete, plastic, and timber piles. Aspects of construction activities other than pile driving are not anticipated to have the potential to result in incidental take of marine mammals because they are either above water or do not produce levels of underwater sound with likely potential to result in marine mammal disturbance. The Navy's waterfront inspection program prioritizes deficiencies in marine structures and plans those maintenance and repairs for design and construction. The Navy's proposed activities include individual projects (where an existing need has been identified and funds have been requested) and estimates for emergent or emergency repairs. The latter are also referred to as contingency repairs. Estimates of activity levels for contingency repairs are based on Navy surveys of existing structures, which provide assessments of structure condition and estimates of numbers of particular pile types that may require replacement (at an assumed 1:1 ratio) over the 5-year duration of these proposed regulations. Additional allowance is made for the likelihood that future waterfront inspections will reveal unexpected damage, or that damage caused by severe weather events and/or incidents caused by vessels will result in need for additional contingency repairs. This regional programmatic approach to MMPA compliance is expected to result in significantly increased efficiency for both the Navy and NMFS, while satisfying the requirements of the MMPA. The regulations proposed here (and any issued LOAs) would replace multiple project-specific incidental take authorization requests for actions that are small in scale, similar in nature, and located within a similar geographic area. The detailed discussion of planned or anticipated projects provided here and in the Navy's application allow for more comprehensive analysis, while providing a reduction in the time and effort necessary to obtain individual incidental take authorizations. LOAs could be issued for projects conducted at any of the six facilities if they fit within the structure of the programmatic analysis provided herein and are able to meet the requirements described in the regulations. The Navy would meet with NMFS on an annual basis prior to the start of in-water work windows to review upcoming projects, required monitoring plans, and the results of relevant projects conducted in the preceding in-water work window. The intent is to utilize lessons learned to better inform potential effects of future MPR activities and in any follow-up consultations. Dates and Duration The proposed regulations would be valid for a period of five years (2018-2023). The specified activities may occur at any time during the five-year period of validity of the proposed regulations, subject to existing timing restrictions. These timing restrictions, or in-water work windows, are typically designed to protect fish species listed under the Endangered Species Act (ESA). For NBK Bangor and Zelatched Point (located in Hood Canal), in-water work may occur from July 16 through January 15. At the remaining four facilities (located in Puget Sound), in-water work may occur from July 16 through February 15. For many projects the design details are not known; thus, it is not possible to state the number of pile driving days that will be required. Days of pile driving at each site were based on the estimated work days using a slow production rate, i.e., one pile removed per day and one pile installed per day for contingency pile driving and an average production rate of six piles per day for fender pile replacement. These conservative rates give the following estimates of total days at each facility over the 5-year duration: NBK Bangor, 119 days; Zelatched Point, 20 days; NBK Bremerton, 168 days; NBK Keyport, 20 days; NBK Manchester, 50 days; and NS Everett, 78 days. These totals include both extraction and installation of piles, and represent a conservative estimate of pile driving days at each facility. In a real construction situation, pile driving production rates would be maximized when possible and actual daily production rates may be higher, resulting in fewer actual pile driving days. Specified Geographical Region The six installations are located within the inland waters of Washington State. Two facilities are located within Hood Canal, while the remainder are located within Puget Sound. Please see Figure 1-1 of the Navy's application for a regional map. For full details regarding the specified geographical region, please see section 2 of the Navy's application. The region is affected by high amounts of runoff from the Fraser River, which stimulates primary productivity, carrying nutrients northwards past Vancouver Island year-round. Puget Sound is one of the largest estuaries in the United States and is a place of great physical and ecological complexity and productivity. The average surface water temperature is 12.8 °C in summer and 7.2 °C in winter (Staubitz et al., 1997), but surface waters frequently exceed 20°C in the summer and fall. With nearly six million people (doubled since the 1960s), Puget Sound is also heavily influenced by human activity. NBK Bangor is located on the Hood Canal, a long, narrow, fjord-like basin of western Puget Sound. Please see Figure 1-2 of the Navy's application. Oriented northeast to southwest, the portion of the canal from Admiralty Inlet to a large bend, called the Great Bend, at Skokomish, Washington, is 84 kilometers (km) long. East of the Great Bend, the canal extends an additional 15 mi to Belfair. Throughout its 108-km length, the width of the canal varies from 1.6 to 3.2 km and exhibits strong depth/elevation gradients. Hood Canal is characterized by relatively steep sides and irregular seafloor topography. In northern Hood Canal, water depths in the center of the waterway near Admiralty Inlet vary between 91 and 128 meters (m). As the canal extends southwestward toward the Olympic Mountain Range and Thorndyke Bay, water depth decreases to approximately 49 m over a moraine deposit. This deposit forms a sill across the canal in the vicinity of Thorndyke Bay, which limits seawater exchange with the rest of Puget Sound. The NBK Bangor waterfront occupies approximately 8 km of the shoreline within northern Hood Canal (1.7 percent of the entire Hood Canal coastline) and lies just south of the sill feature. Zelatched Point is located on the southwestern end of the Toandos Peninsula on Dabob Bay within Hood Canal. Please see Figure 1-6 of the Navy's application. It is approximately 6.4 km west of the NBK Bangor waterfront on the western facing portion of Toandos Peninsula. Dabob Bay is a 183-m deep fjord-like basin with a 101-m sill at its entrance. It runs north 19 km from its junction with Hood Canal. The width of the Dabob Bay is approximately 4.5 km at the Zelatched Point pier. NBK Bremerton is located on the north side of Sinclair Inlet in southern Puget Sound. Please see Figure 1-3 of the Navy's application. Sinclair Inlet is located off the main basin of Puget Sound and is about 6.9 long and 1.9 km wide. The inlet is connected to the main basin through Port Orchard Narrows and Rich Passage. Another relatively narrow waterway, Port Washington Narrows, connects Sinclair Inlet to Dyes Inlet. In-water structures, shoreline fill, and erosion protection at NBK Bremerton have resulted in a shoreline geometry and character that is quite different from undisturbed shorelines in Puget Sound. Bathymetry near existing piers and in turning basins immediately offshore has been altered by significant dredging to accommodate aircraft carriers and other Navy vessels. Water depths range from 12 to 14 m, increasing to 14 to 15 m in dredged berthing areas. West of the project sites, further into the inlet, depths gradually decrease to less than 9 m. NBK Keyport is located on the eastern shore of the Kitsap Peninsula, approximately 24 km due west of Seattle and 16 km north of the city of Bremerton. Please see Figure 1-4 of the Navy's application. Keyport Pier is located along the shores of Liberty Bay, which flows into Port Orchard Bay and then through the narrow Agate Passage to the northeast and Port Orchard Narrows to the south. Liberty Bay and waters adjacent to Keyport are relatively shallow with water depths no greater than 30 m. Water depths increase from the northwest to south/southeast and are greatest in the southern portion of the Port Orchard Narrows. NBK Manchester is located on Orchard Point, approximately 6.4 km due east of Bremerton. Please see Figure 1-5 of the Navy's application. The installation is bounded by Clam Bay to the northwest, Rich Passage to the northeast, and Puget Sound to the east. NBK Manchester piers are located on the north side of Orchard Point and in a small embayment open on the south side of Orchard Point. In Clam Bay, the bathymetry is gently sloping with depths in the outer portions of the bay of approximately 5.5 m below mean lower low water (MLLW). Depths off Orchard Point drop off dramatically to 18 m below MLLW approximately 150 m from shore and 90 m below MLLW 1.6 km offshore. Rich Passage is a shallow sill, less than 21 m deep. NS Everett is located in Port Gardner Bay in Puget Sound's Whidbey Basin. Please see Figure 1-7 of the Navy's application. To the west of the installation is the channelized mouth of the Snohomish River bounded by Jetty Island, which is composed of sediment from maintenance dredging and acts as a breakwater for the northwest area along the installation's waterfront. Jetty Island separates Port Gardner Bay and Possession Sound from the Snohomish River channel. The mouth of the Snohomish River channel is a historically industrialized area of highly modified shorelines and dredged waterways that forms a protected harbor within Port Gardner Bay. East of Jetty Island lies the Snohomish River estuary, consisting of a series of interconnected sloughs that flow through the lowlands east and north of the river's main channel. Water depths in Possession Sound range from about 9 m near the industrialized shoreline in Port Gardner to 180 m in mid-channel. Detailed Description of Activities As described above, the Navy has requested incidental take regulations for its MPR program, which includes maintenance and repair activities at marine waterfront structures at six installations within Washington inland waters. In order to address identified deficiencies in existing marine structures at the six facilities, the Navy proposes to replace up to 822 structurally unsound piles over the 5-year period using both impact and vibratory pile driving. Existing marine structures at the six facilities are identified in Table 1-2 of the Navy's application. The MPR program includes pile repair, extraction, and installation, all of which may be accomplished through a variety of methods. However, only pile extraction and installation using vibratory and impact pile drivers is expected to have the potential to result in incidental take of marine mammals. Pile repair methods include stubbing, wrapping, pile encapsulation, welding, or coating. These processes do not involve pile driving and are not expected to have the potential to result in elevated noise levels or incidental take of marine mammals. Pile removal may be accomplished via mechanical methods such as cutting/chipping, clamshell removal, or direct pull. Water jetting may also be used to aid in pile installation. Noise levels produced through these activities are not expected to exceed baseline levels produced by other routine activities and operations at the six facilities, and any elevated noise levels produced through these activities are expected to be intermittent, of short duration, and with low peak values. Therefore, only vibratory and impact pile driving are carried forward for further analysis. To minimize underwater noise impacts on marine species, vibratory pile driving will be the primary method used to install new steel piles. Vibratory hammers, which can be used to either install or extract a pile, contain a system of counter-rotating eccentric weights powered by hydraulic motors, and are designed in such a way that horizontal vibrations cancel out, while vertical vibrations are transmitted into the pile. The pile driving machine is lifted and positioned over the pile by means of an excavator or crane, and is fastened to the pile by a clamp and/or bolts. The vibrations produced cause liquefaction of the substrate surrounding the pile, enabling the pile to be extracted or driven into the ground using the weight of the pile plus the hammer. Impact hammers use a rising and falling piston to repeatedly strike a pile and drive it into the ground. Impact or vibratory driving could occur on any work day within in-water work windows during the period of validity of these proposed regulations. Steel piles are typically vibratory-driven for their initial embedment depths or to refusal and finished with an impact hammer for proofing or until the pile meets structural requirements, as necessary. Proofing involves striking a driven pile with an impact hammer to verify that it provides the required load-bearing capacity, as indicated by the number of hammer blows per foot of pile advancement. Non-steel piles (concrete, timber, or plastic) are typically impact-driven for their entire embedment depth, in part because non-steel piles are often displacement piles (as opposed to pipe piles) and require some impact to allow substrate penetration. Pile installation can typically take a minute or less to 60 minutes depending on pile type, pile size, and conditions ( i.e., bedrock, loose soils, etc.) to reach the required tip elevation. The most effective and efficient method of pile installation and removal available would be implemented. The method fitting these criteria may vary based on specific project requirements and local conditions. Impact driving, while generally producing higher levels of sound, also minimizes the net amount of active driving time, thus reducing the amount of time during which marine mammals may be exposed to noise. Impact or vibratory pile driving could occur on any day, but would not occur simultaneously. Location-specific pile totals are given in Table 1 and described below. These totals assume a 1:1 replacement ratio; however, the actual number installed may result in a replacement ratio of less than 1:1. Please see Table A-1 of the Navy's application for additional detail regarding expectations for both planned work and possible contingency work. Table 1—Pile Types and Maximum Anticipated Number To Be Replaced at Each Installation Installation Existing piles to be replaced Anticipated piles to be installed NBK Bangor 44 concrete; 75 steel and/or timber 119 steel or concrete. NBK Bremerton 75 steel and/or timber; 460 timber 100 steel (14-in diameter and sheet piles); 435 concrete. NBK Keyport 20 steel and/or concrete 20 steel. NBK Manchester 50 timber and/or plastic 50 concrete, timber, and/or plastic. Zelatched Point 20 timber 20 steel, concrete, and/or timber. NS Everett 1 steel, 2 concrete, and 75 timber 1 steel and 77 concrete and/or timber. Steel piles would be a maximum size of 36-inch (in) diameter except at NBK Bremerton where they would be 14-in diameter. Concrete piles will be a maximum of 24-in diameter and timber/plastic piles will be a maximum of 18-in diameter. For purposes of analysis, it is assumed that any unknown pile type would be steel, since this would give a worst-case scenario in terms of noise levels produced. All concrete, timber, and plastic piles are assumed to be installed entirely by impact pile driver, and all steel piles are assumed to require some use of an impact driver. This is a conservative assumption, as all steel piles would be initially driven with a vibratory driver until they reach a point of refusal (where substrate conditions make use of a vibratory hammer ineffective) or engineering specifications require impact driving to verify load-bearing capacity. Therefore, some steel piles may not in fact require use of the impact driver during installation. At this time, of 822 piles expected to be installed as replacement piles, 121 have been identified as steel piles. These piles would be installed over the 5-year duration at NBK Bremerton, NBK Keyport, and NS Everett. In addition, another 139 piles that would be installed at NBK Bangor (119) and Zelatched Point (20) have not been identified as to pile type and could be steel, concrete, timber or plastic. For this analysis, it is assumed all 139 of these would be steel piles. Therefore, 260 piles are assumed to be steel, with 100 of these 14-in and the remainder assumed to be 36-in diameter. A total of 435 replacement piles have been identified as concrete (NBK Bremerton). The remaining 127 replacement piles (NBK Manchester and NS Everett) could ultimately be concrete, timber, or plastic, but are assumed for purposes of analysis to be concrete, which is a more conservative noise scenario. NBK Bangor is the Pacific homeport for the Navy's TRIDENT submarine fleet with the mission to support and maintain a TRIDENT submarine squadron and other ships home-ported or moored at the installation and to maintain and operate administrative and personnel support facilities including security, berthing, messing, and recreational services. NBK Bangor is the only naval installation on the west coast with the specialized infrastructure able to support the TRIDENT program. The specialized infrastructure includes buildings, utilities, and systems used to support missile production shops, missile maintenance, missile component storage, and missile handling cranes, in addition to providing security and operational port facilities. Pile-supported structures at the NBK Bangor waterfront include: Carderock Pier, Service Pier, Keyport-Bangor (K/B) Dock, Delta Pier, Marginal Wharf, Explosives Handling Wharf #1 (EHW-1), and the Magnetic Silencing Facility (see Figure 1-2 of the Navy's application). Over the 5-year duration, up to 44 piles are anticipated to be replaced at EHW-1 and up to 75 piles could be installed at any of the structures for emergent projects. Zelatched Point supports test and evaluation operations conducted by the Naval Undersea Warfare Center Keyport within Dabob Bay, and contains a single pier historically used for mooring small craft and float planes during Navy range operations in Dabob Bay (see Figure 1-6 of the Navy's application). Two dolphins are located at the outboard end of the facility, each consisting of three timber piles. Up to 20 piles of any type are anticipated for emergent/emergency repairs during the course of the 5-year duration. Puget Sound Naval Shipyard and Intermediate Maintenance Facility is the major tenant command of NBK Bremerton. NBK Bremerton contains multiple dry docks, piers, and wharfs and is capable of overhauling and repairing, constructing, deactivating, and dry-docking all types and sizes of ships. It also serves as the homeport for a nuclear aircraft carrier and other Navy vessels. There are 13 pile-supported structures located at NBK Bremerton (see Figure 1-3 of the Navy's application). Two pile repair and replacement projects are planned for Piers 4 and 5. The project at Pier 4 would involve replacing missing or broken timber fender piles with 80 steel fender piles. Steel piles would be up to 14-in diameter and installed with a vibratory driver and only impact driven if they cannot be advanced to tip elevation using a vibratory driver. Prior projects at Piers 4 and 5 indicate steel piles will be able to be vibratory driven. However, some impact driving may be necessary. The project at Pier 5 would replace an existing primarily timber fendering system, with 360 concrete piles ranging in size up to 24-in diameter. All concrete piles are anticipated to be impact driven. Work on Piers 5, 6, 7, Mooring A, and Dry Dock 5 will involve replacement of up to 20 timber piles with 20 sheet steel piles. In addition, 75 concrete piles are anticipated for emergent/emergency repairs over the 5-year duration. Naval Undersea Warfare Center Keyport is the major tenant command at NBK Keyport and is the Navy's premier provider of cold-water testing and evaluation for undersea warfare systems. In this capacity, NBK Keyport provides depot maintenance and repair, in-service engineering, and fleet industrial support for torpedoes and other undersea warfare systems including mobile mines, unmanned underwater vehicles, and countermeasures. There is one pier, Keyport Pier, in the northern portion of the NBK Keyport installation (see Figure 1-4 of the Navy's application). There are no planned pile repair and replacement projects at NBK Keyport; however, up to 20 piles are anticipated for emergent/emergency repairs or replacement at the Keyport Pier during the course of the 5-year duration. NBK Manchester provides bulk fuel and lubricant support to area Navy afloat and shore activities. The primary pile-supported structures at NBK Manchester are the fuel pier and the finger pier with a barge mooring platform and a small boat float (see Figure 1-5 of the Navy's application). There are no planned projects at NBK Manchester. A contingency estimate of 50 concrete, timber, or plastic piles for emergent/emergency repairs at the fuel pier or finger pier is proposed for the 5-year duration. NS Everett provides homeport ship berthing, industrial support, and a Navy administrative center. Pile-supported structures at NS Everett include Piers A, B, C, D, and E; North Wharf and South Wharf; a recreational marina; and the small boat launch (see Figure 1-7 of the Navy's application). Additionally, there are fender piles along the waterfront areas. Repairs to the North Wharf could require replacement of up to two concrete piles. Additionally, contingency planning estimated up to 75 concrete or timber piles and one steel pile could be repaired or replaced over the 5-year duration. Description of Marine Mammals in the Area of the Specified Activity We have reviewed the Navy's species descriptions—which summarize available information regarding status and trends, distribution and habitat preferences, behavior and life history, and auditory capabilities of the potentially affected species—for accuracy and completeness and refer the reader to Sections 3 and 4 of the Navy's application, instead of reprinting the information here. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SAR; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS's website ( www.fisheries.noaa.gov/find-species ). Table 2 lists all species with expected potential for occurrence in the specified geographical region where the Navy proposes to conduct the specified activities and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and potential biological removal (PBR), where known. For taxonomy, we follow Committee on Taxonomy (2017). PBR, 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, is considered in concert with known sources of ongoing anthropogenic mortality (as described in NMFS's SARs). Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. All managed stocks in the specified geographical regions are assessed in either NMFS's U.S. Alaska SARs or U.S. Pacific SARs. All values presented in Table 2 are the most recent available at the time of writing and are available in the draft 2017 SARs (available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports ). Ten species (with 13 managed stocks) are considered to have the potential to co-occur with Navy activities. There are several species or stocks that occur in Washington inland waters, but which are not expected to occur in the vicinity of the six Naval installations. These species may occur in waters of the Strait of Juan de Fuca or in more northerly waters in the vicinity of the San Juan Islands and areas north to the Canadian border, and include the Pacific white-sided dolphin ( Lagenorhynchus obliquidens ) and the northern resident stock of killer whales. In addition, the sea otter is found in coastal waters, with the northern (or eastern) sea otter ( Enhydra lutris kenyoni ) found in Washington. However, sea otters are managed by the U.S. Fish and Wildlife Service and are not considered further in this document. Two populations of gray whales are recognized, eastern and western North Pacific (ENP and WNP). WNP whales are known to feed in the Okhotsk Sea and off of Kamchatka before migrating south to poorly known wintering grounds, possibly in the South China Sea. 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 (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., 2011; 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, there is no indication that WNP whales occur in waters of Hood Canal or southern Puget Sound, and it is extremely unlikely that a gray whale in close proximity to Navy 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 Navy construction activities is insignificant and discountable, and WNP gray whales are omitted from further analysis. 1 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; N min is the minimum estimate of stock abundance. In some cases, CV is not applicable. For two stocks of killer whales, the abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore. 3 These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented in the draft 2017 SARs. 4 Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2017). 5 The abundance estimate for this stock includes only animals from the “inner coast” population occurring in inside waters of southeastern Alaska, British Columbia, and Washington—excluding animals from the “outer coast” subpopulation, including animals from California—and therefore should be considered a minimum count. For comparison, the previous abundance estimate for this stock, including counts of animals from California that are now considered outdated, was 354. 6 Abundance estimates for these stocks are not considered current. PBR is therefore considered undetermined for these stocks, 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. 7 This stock is known to spend a portion of time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is a portion of the total. The total PBR for humpback whales is 22 (one half allocation for U.S. waters). Annual M/SI presented for these species is for U.S. waters only. Table 2—Marine Mammals Potentially Present in the Vicinity of Navy Construction 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 Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) Family Eschrichtiidae: Gray whale Eschrichtius robustus Eastern North Pacific -; N 20,990 (0.05; 20,125; 2011) 624 132 Family Balaenopteridae (rorquals): Humpback whale Megaptera novaeangliae kuzira California/Oregon/Washington (CA/OR/WA) E/D; Y 1,918 (0.03; 1,876; 2014) 7 11 ≥9.2 Minke whale Balaenoptera acutorostrata scammoni CA/OR/WA -; N 636 (0.72; 369; 2014) 3.5 ≥1.3 Superfamily Odontoceti (toothed whales, dolphins, and porpoises) Family Delphinidae: Killer whale Orcinus orca 4 West Coast Transient 5 -; N 243 (n/a; 2009) 2.4 0 Eastern North Pacific Southern Resident E/D; Y 83 (n/a; 2016) 0.14 0 Family Phocoenidae (porpoises): Harbor porpoise Phocoena phocoena vomerina Washington Inland Waters -; N 11,233 (0.37; 8,308; 2015) 66 ≥7.2 Dall's porpoise Phocoenoides dalli dalli CA/OR/WA -; N 25,750 (0.45; 17,954; 2014) 172 0.3 Order Carnivora—Superfamily Pinnipedia Family Otariidae (eared seals and sea lions): California sea lion Zalophus californianus United States -; N 296,750 (n/a; 153,337; 2011) 9,200 389 Steller sea lion Eumetopias jubatus monteriensis Eastern U.S. D; Y 41,638 (n/a; 2015) 2,498 108 Family Phocidae (earless seals): Harbor seal Phoca vitulina richardii Washington Northern Inland Waters. 6 -; N 11,036 (0.15; 7,213; 1999) Undet. 9.8 Southern Puget Sound 6 -; N 1,568 (0.15; 1,025; 1999) Undet. 3.4 Hood Canal 6 -; N 1,088 (0.15; 711; 1999) Undet. 0.2 Northern elephant seal Mirounga angustirostris California Breeding -; N 179,000 (n/a; 81,368; 2010) 4,882 8.8 Gray Whale Gray whales are observed in Washington inland waters in all months of the year, with peak numbers from March through June (Calambokidis et al., 2010). Most whales sighted are part of a small regularly occurring group of 6 to 10 whales that use mudflats in the Whidbey Island and Camano Island area as a springtime feeding area (Calambokidis et al., 2010). Observed feeding areas are located in Saratoga Passage between Whidbey and Camano Islands including Crescent Harbor, and in Port Susan Bay located between Camano Island and the mainland north of Everett. Gray whales that are not identified with the regularly occurring feeding group are occasionally sighted in Puget Sound. These whales are not associated with feeding areas and are often emaciated (WDFW, 2012). There are typically from 2 to 10 stranded gray whales per year in Washington (Cascadia Research, 2012). In the waterways near NBK Bremerton and Keyport (Rich Passage/Sinclair Inlet/Dyes Inlet/Agate Passage), 11 opportunistic sightings of gray whales were reported to Orca Network (a public marine mammal sightings database) between 2003 and 2012. One stranding occurred at NBK Bremerton in 2013. Gray whales have been sighted in Hood Canal south of the Hood Canal Bridge on six occasions since 1999, including a stranded whale. The most recent report was in 2010. Gray whales are expected to occur in the waters surrounding all of the installations considered here other than those in Hood Canal ( i.e., NBK Bangor and Zelatched Point), due to rarity of occurrence. Gray whales are expected to occur primarily from March through June when in-water construction will not occur. Therefore, although some exposure to individual gray whales could occur at four facilities, project timing will help to minimize potential exposures. Humpback Whale Prior to 2016, humpback whales were listed under the ESA as an endangered species worldwide. Following a 2015 global status review (Bettridge et al., 2015), NMFS established 14 distinct population segments (DPS) with different listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not necessarily equate to the existing stocks designated under the MMPA and shown in Table 2. Because MMPA stocks cannot be portioned, i.e., parts managed as ESA-listed while other parts managed as not ESA-listed, until such time as the MMPA stock delineations are reviewed in light of the DPS designations, NMFS considers the existing humpback whale stocks under the MMPA to be endangered and depleted for MMPA management purposes ( e.g., selection of a recovery factor, stock status). Within U.S. west coast waters, three current DPSs may occur: The Hawaii DPS (not listed), Mexico DPS (threatened), and Central America DPS (endangered). According to Wade et al. (2016), the probability that whales encountered in Washington waters are from a given DPS are as follows: Hawaii, 52.9% (CV = 0.15); Mexico, 41.9% (0.14); Central America, 5.2% (0.91). Most humpback whale sightings reported since 2003 were in the main basin of Puget Sound with numerous sightings in the waters between Point No Point and Whidbey Island, Possession Sound, and southern Puget Sound in the vicinity of Point Defiance. Some of the reported sightings were in the vicinity of NS Everett and NBK Manchester. A few sightings of possible humpback whales were reported by Orca Network in the waters near NBK Bremerton and Keyport (Rich Passage to Agate Passage area including Sinclair and Dyes Inlet) between 2003 and 2015. Humpback whales were sighted in the vicinity of Manette Bridge in Bremerton in 2016 and 2017, and a carcass was found under a dock at NBK Bremerton in 2016 (Cascadia Research, 2016). In Hood Canal, single humpback whales were observed for several weeks in 2012 and 2015. One sighting was reported in 2016. Review of the 2012 sightings information indicated they were of one individual. Prior to the 2012 sightings, there were no confirmed reports of humpback whales entering Hood Canal. The number of humpback whales potentially present near any of the six installations is expected to be very low in any month. Minke Whale Sightings of minke whales in Puget Sound are infrequent, with approximately 14 opportunistic sightings recorded between 2005 and 2012, from March through October. No sightings were reported in the vicinity of NBK Bremerton and Keyport (Rich Passage through the Agate Passage including Sinclair Inlet and Dyes Inlet) or in Hood Canal. The number of minke whales potentially present near any of the six installations is expected to be very low in any month and even lower in winter months. Killer Whale (Transient) Groups of transient killer whales were observed for lengthy periods in Hood Canal in 2003 (59 days) and 2005 (172 days) (London, 2006), but were not observed again until 2016, when they were seen on a handful of days between March and May (including in Dabob Bay). Transient killer whales have been seen infrequently near NBK Bremerton, including in Dyes Inlet and Sinclair Inlet ( e.g., sightings in 2010, 2013, and 2015). Sightings in the vicinity of NBK Keyport have also been infrequent, and no records were found for Rich Passage in the vicinity of NBK Manchester. Transient killer whales have been observed in Possession Sound near NS Everett. West Coast transient killer whales most often travel in small pods averaging four individuals (Baird and Dill, 1996); however, the most commonly observed group size in Puget Sound (waters east of Admiralty Inlet, including Hood Canal, through South Puget Sound and north to Skagit Bay) from 2004 to 2010 was 6 whales (Houghton et al., 2015). Killer Whales (Resident) Critical habitat for southern resident killer whales, designated pursuant to the ESA, includes three specific areas: (1) Summer core area in Haro Strait and waters around the San Juan Islands; (2) Puget Sound; and (3) Strait of Juan de Fuca (71 FR 69054; November 29, 2006). The primary constituent elements essential for conservation of the habitat are: (1) Water quality to support growth and development; (2) Prey species of sufficient quantity, quality, and availability to support individual growth, reproduction, and development, as well as overall population growth; and (3) Passage conditions to allow for migration, resting, and foraging. However, the six naval installations are specifically excluded from the critical habitat designation. A revision to the critical habitat designation is currently under consideration (80 FR 9682; February 24, 2015). Southern resident killer whales are expected to occur occasionally in the waters surrounding all of the installations except those in Hood Canal, where they have not been reported since 1995 (NMFS, 2006). Southern resident killer whales are rare near NBK Bremerton and Keyport, with the last confirmed sighting in Dyes Inlet in 1997. Southern residents have been observed in Saratoga Passage and Possession Sound near NS Everett. The stock contains three pods (J, K, and L pods), with pod sizes ranging from approximately 20 (in J pod) to 40 (in L pod) individuals. Group sizes encountered can be smaller or larger if pods temporarily separate or join together. Therefore, some exposure to groups of up to 20 individuals or more could occur over the 5-year duration. Harbor Porpoise Sightings in Hood Canal have increased in recent years, and an average of six harbor porpoises were sighted per day in deeper waters during line transect vessel surveys conducted in 2011 near NBK Bangor and Dabob Bay (HDR, 2012). Mean group size of harbor porpoises for each survey season in the 2013-2016 aerial surveys was 1.7 (Smultea et al., 2017). Site-specific information is not available for NBK Bremerton, Keyport, or Manchester, but harbor porpoises have been seen infrequently at NS Everett. Dall's Porpoise Dall's porpoise are known to occur in Puget Sound, and have been sighted as far south as Carr Inlet in southern Puget Sound and as far north as Saratoga Passage, north of NS Everett (Nysewander et al., 2005; WDFW, 2008). Dall's porpoise could also occasionally occur in Hood Canal. with the last observation in deeper water near NBK Bangor in 2008 (Tannenbaum et al., 2009). However, Dall's porpoise were not observed during vessel line-transect surveys and other monitoring efforts completed in Hood Canal (including Dabob Bay) in 2011 (HDR, 2012). Dall's porpoises have not been documented in the Rich Passage to Agate Passage area in the vicinity of NBK Bremerton or Keyport, but have been observed in Possession Sound near NS Everett (primarily during winter) (Nysewander et al., 2005; WDFW, 2008). Dall's porpoises could be present in waters in the vicinity of any of the installations considered here, and are considered more likely to occur during winter months than summer months in groups of up to 25 individuals. The Navy conducts surveys at installations with known pinniped haul-outs, which are located at NBK Bangor, NBK Bremerton, NBK Manchester, and NS Everett (see Figures 4-2, 4-3, 4-4, and 4-5 of the Navy's application). More detail regarding these surveys may be found in Appendix C of the Navy's application. Steller Sea Lion Steller sea lions have been seasonally documented during shore-based surveys at NBK Bangor in Hood Canal since 2008, with up to 13 individuals observed hauled out on submarines at Delta Pier. Steller sea lions begin arriving at NBK Bangor in September and depart by the end of May. Shore-based surveys at NBK Bremerton have not detected Steller sea lions since the surveys were initiated in 2010. A Steller sea lion was sighted on the floating security barrier in 2012 and others were detected during aerial surveys conducted by the Washington Department of Fish and Wildlife (WDFW) in 2013 (Jeffries, 2013). Steller sea lions haul out on floating platforms in Clam Bay approximately 800 m offshore from the Manchester Fuel Depot's finger pier, approximately 13 km from NBK Bremerton. The Navy conducted surveys of sea lions on the floats from 2012 through 2016; Steller sea lions were seen in all surveyed months except for June, July, and August with as many as 42 individuals present in November 2014. Aerial surveys were conducted by WDFW from March-April 2013, July-August 2013, November 2013, and February 2014. These surveys detected Steller sea lions on the floating platforms during all survey months except July and August, with up to 37 individuals present on one survey in November 2013. No haul-outs are known in the vicinity of NBK Keyport or Zelatched Point; therefore, no shore-based surveys have been conducted at these installations. No opportunistic sightings have been reported at these installations. The nearest Steller sea lion haul-outs to NBK Keyport are navigation buoys that can support at most two individuals, located over 15 km away in Puget Sound. Therefore, Steller sea lions are not expected to frequent waters off this installation. The only Steller sea lion haul-out in Hood Canal is at NBK Bangor, as described above, which is over 14 km from Zelatched Point. Shore-based surveys conducted from July 2012 through June 2014 at NS Everett did not detect Steller sea lions. However, occasional observations have been reported from the port security barrier (PSB). Other than these detections on the installation's PSBs, the nearest known Steller sea lion haul-out is 22.5 km away; therefore, Steller sea lions are not expected to occur in waters off this installation. California Sea Lion California sea lion haul-outs occur at NBK Bangor, NBK Bremerton, and NS Everett. California sea lions are typically present most of the year except for mid-June through July in Washington inland waters, with peak abundance numbers between October and May (NMFS, 1997; Jeffries et al., 2000). During summer months and associated breeding periods, the inland waters would not be considered a high-use area by California sea lions, as they would be returning to rookeries in California waters. However, as described below, surveys at Bangor indicate that a few individuals are present through mid-June and have arrived as early as August with at least one individual remaining in July 2014. Surveys at NS Everett from 2012 to 2016 indicate a few individuals may remain year-round. California sea lions have been documented during shore-based surveys at NBK Bangor in Hood Canal since 2008 in all survey months, with as many as 122 individuals observed at one time (November 2013) hauled out on submarines at Delta Pier and on PSB floats. California sea lions have been documented during shore- and boat-based surveys at NBK Bremerton since 2010, with as many as 315 individuals hauled out at one time (November 2015) on PSB floats. California sea lions haul out on floating platforms in Clam Bay approximately 800 m offshore from the Manchester Fuel Depot's finger pier, approximately 13 km from NBK Bremerton. The Navy conducted surveys of sea lions on the floats incidental to other surveys from 2012 through 2016. California sea lions were seen in every survey month except July and August, with as many as 130 individuals present in one survey in October 2014. Aerial surveys were conducted by WDFW from March-April 2013, July-August 2013, November 2013, and February 2014. These surveys detected California sea lions on the floating platforms during all survey months except July, with up to 54 individuals present on one survey in November 2013. California sea lions have been documented during shore-based surveys at NS Everett from 2012 to 2016 in all survey months, with as many as 215 individuals hauled out at one time (April 2016) on PSB floats. No shore-based surveys have been conducted at NBK Keyport or Zelatched Point and no opportunistic sightings have been reported at these installations. No haul-outs are known in the vicinity of these installations. The nearest California sea lion haul-outs to NBK Keyport are navigation buoys that can support at most two individuals, located over 15 km away in Puget Sound. Therefore, California sea lions are not expected to frequent waters off this installation. The only California sea lion haul-out in Hood Canal is at NBK Bangor, as described above, which is over 14 km from Zelatched Point. California sea lions are expected to be exposed to noise from project activities at NBK Bangor, Bremerton, Manchester, and NS Everett because haul-outs are at these installations or nearby. Exposure is estimated to occur primarily from August through the end of the in-water work window in mid-January or early March. Harbor Seal Harbor seals in Washington inland waters have been divided into three stocks: Hood Canal, Northern Inland Waters, and Southern Puget Sound. The range of the northern inland waters stock includes Puget Sound north of the Tacoma Narrows Bridge, the San Juan Islands, and the Strait of Juan de Fuca, while the southern Puget Sound stock range includes waters south of the Tacoma Narrows Bridge. Therefore, animals present at NBK Bremerton, NBK Keyport, NBK Manchester, and NS Everett are most likely to be from the northern inland waters stock, while those present at NBK Bangor and Zelatched Point are expected to be from the Hood Canal stock. Harbor seals are expected to occur year-round at all installations, with the greatest numbers expected at installations with nearby haul-out sites. In Hood Canal, known haul-outs occur on the west side of Hood Canal at the mouth of the Dosewallips River and on the western and northern shorelines in Dabob Bay located approximately 13 and 3.7 km away from NBK Bangor and Zelatched Point, respectively. Site-specific surveys have not been conducted at Zelatched Point because no haul-outs are documented in this part of Dabob Bay. Vessel-based surveys conducted from 2007 to 2010 at NBK Bangor observed harbor seals in every month of surveys (Agness and Tannenbaum, 2009; Tannenbaum et al., 2009, 2011). Harbor seals were routinely seen during marine mammal monitoring for two construction projects (HDR, 2012; Hart Crowser, 2013, 2014, 2015). Small numbers of harbor seals have been documented hauling out opportunistically at NBK Bangor ( e.g., on the PSB floats, wave screen at Carderock Pier, buoys, barges, marine vessels, and logs) and on man-made floating structures near K/B Dock and Delta Pier. Surveys conducted in August and September 2016 recorded as many as 28 harbor seals hauled out under Marginal Wharf or swimming in adjacent waters. On two occasions, four to six individuals were observed hauled out near Delta Pier. Known harbor seal births include one on the Carderock wave screen in August 2011 and at least one on a small floating dock in fall 2013, and afterbirth reported on a float at Magnetic Silencing Facility. In addition, harbor seal pupping has occurred on a section of the Service Pier since approximately 2001. Harbor seal mother and pup sets were observed in 2014 hauled out on the Carderock wave screen and swimming in nearby waters, and swimming in the vicinity of Delta Pier. At NS Everett, Navy surveys conducted regularly from 2012 to 2016 have documented up to 491 harbor seals hauling out adjacent to the installation on log rafts in Notch Basin in the East Waterway. Harbor seals occupy the waters and haul-out sites near NS Everett year-round. Based on the survey data, the number of individuals peaks from August to October, with an average maximum number of 343 seals in October. The log rafts are privately owned and their location can vary within the East Waterway, which ranges from approximately 200-300 m wide. Only harbor seals on logs rafts that are within sight distance from NS Everett are counted, and if visible, numbers on floats outside the Notch Basin are noted, but not counted. Therefore, Navy counts of harbor seals hauled out do not necessarily represent the number of hauled out seals in the East Waterway. Pupping is documented on the log rafts; however, no pup counts have been conducted. No haul-outs have been identified at NBK Bremerton, Keyport, or Manchester. The nearest documented haul-outs to NBK Bremerton are across Sinclair Inlet, approximately 1.1 km away. The nearest documented haul-out to NBK Keyport is in Liberty Bay at the Poulsbo Marina approximately 3.2 km from the Keyport Pier. The nearest documented haul-out to NBK Manchester is Blakely Rocks approximately 5.6 km away on the east side of Bainbridge Island. All haul-outs listed here near the three installations are estimated to have less than 100 individuals. Northern Elephant Seal No haul-outs occur in Puget Sound with the exception of individual elephant seals occasionally hauling out for two to four weeks to molt, usually during the spring and summer and typically on sandy beaches (Calambokidis and Baird, 1994). These animals are usually yearlings or subadults and their haul-out locations are unpredictable. One male subadult elephant seal was observed hauled out to molt at Manchester Fuel Depot in 2004. Although regular haul-outs occur in the Strait of Juan de Fuca, the occurrence of elephant seals in Puget Sound is unpredictable and rare. Unusual Mortality Events (UME) A UME is defined under the MMPA as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” The only currently ongoing UME investigation involves California sea lions along the west coast. Beginning in January 2013, elevated strandings of California sea lion pups were observed in southern California, with live sea lion strandings nearly three times higher than the historical average. Findings to date indicate that a likely contributor to the large number of stranded, malnourished pups was a change in the availability of sea lion prey for nursing mothers, especially sardines. The causes and mechanisms of this remain under investigation ( www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm; accessed November 24, 2017). Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 dB threshold from the normalized composite audiograms, with an exception for lower limits for low-frequency cetaceans where the result was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. The functional groups and the associated frequencies are indicated below (note that these frequency ranges correspond to the range for the composite group, with the entire range not necessarily reflecting the capabilities of every species within that group): • Low-frequency cetaceans (mysticetes): Generalized hearing is estimated to occur between approximately 7 Hz and 35 kHz; • Mid-frequency cetaceans (larger toothed whales, beaked whales, and most delphinids): Generalized hearing is estimated to occur between approximately 150 Hz and 160 kHz; • High-frequency cetaceans (porpoises, river dolphins, and members of the genera Kogia and Cephalorhynchus; including two members of the genus Lagenorhynchus, on the basis of recent echolocation data and genetic data): Generalized hearing is estimated to occur between approximately 275 Hz and 160 kHz; • Pinnipeds in water; Phocidae (true seals): Functional hearing is estimated to occur between approximately 50 Hz to 86 kHz; • Pinnipeds in water; Otariidae (eared seals): Functional hearing is estimated to occur between 60 Hz and 39 kHz for Otariidae. For more detail concerning these groups and associated frequency ranges, please see NMFS (2016) for a review of available information. Ten marine mammal species (six cetacean and four pinniped (two otariid and two phocid) species) have the potential to co-occur with Navy construction activities. Please refer to Table 2. Of the six cetacean species that may be present, three are classified as low-frequency cetaceans ( i.e., all mysticete species), one is classified as a mid-frequency cetacean ( i.e., killer whales), and two are classified as high-frequency cetaceans ( i.e., porpoises). Potential Effects of the Specified Activity on Marine Mammals and Their Habitat This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The “Estimated Take” section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The “Negligible Impact Analysis and Determination” section considers the content of this section and the material it references, the “Estimated Take” section, and the “Proposed Mitigation” section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks. In the following discussion, we provide general background information on sound before considering potential effects to marine mammals from sound produced by pile driving. Description of Sound Sources This section contains a brief technical background on sound, on the characteristics of certain sound types, and on metrics used in this proposal inasmuch as the information is relevant to the specified activity and to a discussion of the potential effects of the specified activity on marine mammals found later in this document. For general information on sound and its interaction with the marine environment, please see, e.g., Au and Hastings (2008); Richardson et al. (1995); Urick (1983). Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in hertz (Hz) or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the decibel (dB). A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal (μPa)), and is a logarithmic unit that accounts for large variations in amplitude; therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa), while the received level is the SPL at the listener's position (referenced to 1 μPa). Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Root mean square is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average (Urick, 1983). Root mean square accounts for both positive and negative values; squaring the pressures makes all values positive so that they may be accounted for in the summation of pressure levels (Hastings and Popper, 2005). This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures. Sound exposure level (SEL; represented as dB re 1 μPa 2 -s) represents the total energy in a stated frequency band over a stated time interval or event, and considers both intensity and duration of exposure. The per-pulse SEL is calculated over the time window containing the entire pulse ( i.e., 100 percent of the acoustic energy). SEL is a cumulative metric; it can be accumulated over a single pulse, or calculated over periods containing multiple pulses. Cumulative SEL represents the total energy accumulated by a receiver over a defined time window or during an event. Peak sound pressure (also referred to as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source, and is represented in the same units as the rms sound pressure. When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams or may radiate in all directions (omnidirectional sources), as is the case for sound produced by the pile driving activity considered here. The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones. Even in the absence of sound from the specified activity, the underwater environment is typically loud due to ambient sound, which is defined as environmental background sound levels lacking a single source or point (Richardson et al., 1995). The sound level of a region is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical ( e.g., wind and waves, earthquakes, ice, atmospheric sound), biological ( e.g., sounds produced by marine mammals, fish, and invertebrates), and anthropogenic ( e.g., vessels, dredging, construction) sound. A number of sources contribute to ambient sound, including wind and waves, which are a main source of naturally occurring ambient sound for frequencies between 200 hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient sound levels tend to increase with increasing wind speed and wave height. Precipitation can become an important component of total sound at frequencies above 500 Hz, and possibly down to 100 Hz during quiet times. Marine mammals can contribute significantly to ambient sound levels, as can some fish and snapping shrimp. The frequency band for biological contributions is from approximately 12 Hz to over 100 kHz. Sources of ambient sound related to human activity include transportation (surface vessels), dredging and construction, oil and gas drilling and production, geophysical surveys, sonar, and explosions. Vessel noise typically dominates the total ambient sound for frequencies between 20 and 300 Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz and, if higher frequency sound levels are created, they attenuate rapidly. The sum of the various natural and anthropogenic sound sources that comprise ambient sound at any given location and time depends not only on the source levels (as determined by current weather conditions and levels of biological and human activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 decibels (dB) from day to day (Richardson et al., 1995). The result is that, depending on the source type and its intensity, sound from the specified activity may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. Underwater ambient sound in Puget Sound is comprised of sounds produced by a number of natural and anthropogenic sources and varies both geographically and temporally. Human-generated sound is a significant contributor to the ambient acoustic environment at the installations considered here. The underwater acoustic environment at each installation will vary depending on the amount of anthropogenic activity, weather conditions, and tidal currents. In high-use installations, such as NBK Bremerton, anthropogenic noise may dominate the ambient soundscape. In areas with less anthropogenic activity ( e.g., Zelatched Point), ambient sound is likely to be dominated by sound from natural sources. Under normal weather and traffic conditions, average ambient sound at all installations is assumed to be below 120 dB rms. More detail regarding specific installations is available in section 2.3.1.5 of the Navy's application. Details of source types are described in the following text. Sounds are often considered to fall into one of two general types: Pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward, 1997 in Southall et al., 2007). Please see Southall et al. (2007) for an in-depth discussion of these concepts. The distinction between these two sound types is not always obvious, as certain signals share properties of both pulsed and non-pulsed sounds. A signal near a source could be categorized as a pulse, but due to propagation effects as it moves farther from the source, the signal duration becomes longer ( e.g., Greene and Richardson, 1988). Pulsed sound sources ( e.g., airguns, explosions, gunshots, sonic booms, impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal pressure value followed by a rapid decay period that may include a period of diminishing, oscillating maximal and minimal pressures, and generally have an increased capacity to induce physical injury as compared with sounds that lack these features. Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or intermittent (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses ( e.g., rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems. The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment. The impulsive sound generated by impact hammers is characterized by rapid rise times and high peak levels. Vibratory hammers produce non-impulsive, continuous noise at levels significantly lower than those produced by impact hammers. Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time ( e.g., Nedwell and Edwards, 2002; Carlson et al., 2005). Acoustic Effects We previously provided general background information on marine mammal hearing (see “Description of Marine Mammals in the Area of the Specified Activity”). Here, we discuss the potential effects of sound on marine mammals. Potential Effects of Underwater Sound —Note that, in the following discussion, we refer in many cases to a review article concerning studies of noise-induced hearing loss conducted from 1996-2015 ( i.e., Finneran, 2015). For study-specific citations, please see that work. Anthropogenic sounds cover a broad range of frequencies and sound levels and can have a range of highly variable impacts on marine life, from none or minor to potentially severe responses, depending on received levels, duration of exposure, behavioral context, and various other factors. The potential effects of underwater sound from active acoustic sources can potentially result in one or more of the following: Temporary or permanent hearing impairment, non-auditory physical or physiological effects, behavioral disturbance, stress, and masking (Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007; Götz et al., 2009). The degree of effect is intrinsically related to the signal characteristics, received level, distance from the source, and duration of the sound exposure. In general, sudden, high level sounds can cause hearing loss, as can longer exposures to lower level sounds. Temporary or permanent loss of hearing will occur almost exclusively for noise within an animal's hearing range. We first describe specific manifestations of acoustic effects before providing discussion specific to pile driving. Richardson et al. (1995) described zones of increasing intensity of effect that might be expected to occur, in relation to distance from a source and assuming that the signal is within an animal's hearing range. First is the area within which the acoustic signal would be audible (potentially perceived) to the animal but not strong enough to elicit any overt behavioral or physiological response. The next zone corresponds with the area where the signal is audible to the animal and of sufficient intensity to elicit behavioral or physiological responsiveness. Third is a zone within which, for signals of high intensity, the received level is sufficient to potentially cause discomfort or tissue damage to auditory or other systems. Overlaying these zones to a certain extent is the area within which masking ( i.e., when a sound interferes with or masks the ability of an animal to detect a signal of interest that is above the absolute hearing threshold) may occur; the masking zone may be highly variable in size. We describe the more severe effects ( i.e., certain non-auditory physical or physiological effects) only briefly as we do not expect that there is a reasonable likelihood that pile driving may result in such effects (see below for further discussion). Potential effects from impulsive sound sources can range in severity from effects such as behavioral disturbance or tactile perception to physical discomfort, slight injury of the internal organs and the auditory system, or mortality (Yelverton et al., 1973). Non-auditory physiological effects or injuries that theoretically might occur in marine mammals exposed to high level underwater sound or as a secondary effect of extreme behavioral reactions ( e.g., change in dive profile as a result of an avoidance reaction) caused by exposure to sound include neurological effects, bubble formation, resonance effects, and other types of organ or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 2007; Tal et al., 2015). The construction activities considered here do not involve the use of devices such as explosives or mid-frequency tactical sonar that are associated with these types of effects. Threshold Shift —Marine mammals exposed to high-intensity sound, or to lower-intensity sound for prolonged periods, can experience hearing threshold shift (TS), which is the loss of hearing sensitivity at certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), in which case the loss of hearing sensitivity is not fully recoverable, or temporary (TTS), in which case the animal's hearing threshold would recover over time (Southall et al., 2007). Repeated sound exposure that leads to TTS could cause PTS. In severe cases of PTS, there can be total or partial deafness, while in most cases the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985). When PTS occurs, there is physical damage to the sound receptors in the ear ( i.e., tissue damage), whereas TTS represents primarily tissue fatigue and is reversible (Southall et al., 2007). In addition, other investigators have suggested that TTS is within the normal bounds of physiological variability and tolerance and does not represent physical injury ( e.g., Ward, 1997). Therefore, NMFS does not consider TTS to constitute auditory injury. Relationships between TTS and PTS thresholds have not been studied in marine mammals, and there is no PTS data for cetaceans, but such relationships are assumed to be similar to those in humans and other terrestrial mammals. PTS typically occurs at exposure levels at least several decibels above (a 40-dB threshold shift approximates PTS onset; e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB threshold shift approximates TTS onset; e.g., Southall et al. 2007). Based on data from terrestrial mammals, a precautionary assumption is that the PTS thresholds for impulse sounds (such as impact pile driving pulses as received close to the source) are at least 6 dB higher than the TTS threshold on a peak-pressure basis and PTS cumulative sound exposure level thresholds are 15 to 20 dB higher than TTS cumulative sound exposure level thresholds (Southall et al., 2007). Given the higher level of sound or longer exposure duration necessary to cause PTS as compared with TTS, it is considerably less likely that PTS could occur. TTS is the mildest form of hearing impairment that can occur during exposure to sound (Kryter, 1985). While experiencing TTS, the hearing threshold rises, and a sound must be at a higher level in order to be heard. In terrestrial and marine mammals, TTS can last from minutes or hours to days (in cases of strong TTS). In many cases, hearing sensitivity recovers rapidly after exposure to the sound ends. Few data on sound levels and durations necessary to elicit mild TTS have been obtained for marine mammals. Marine mammal hearing plays a critical role in communication with conspecifics, and interpretation of environmental cues for purposes such as predator avoidance and prey capture. Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious. For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that occurs during a time where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during time when communication is critical for successful mother/calf interactions could have more serious impacts. Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin ( Tursiops truncatus ), beluga whale ( Delphinapterus leucas ), harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis )) and three species of pinnipeds (northern elephant seal, harbor seal, and California sea lion) exposed to a limited number of sound sources ( i.e., mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). TTS was not observed in trained spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran, 2015). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. There are no data available on noise-induced hearing loss for mysticetes. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall et al. (2007), Finneran and Jenkins (2012), Finneran (2015), and NMFS (2016). Behavioral Effects —Behavioral disturbance may include a variety of effects, including subtle changes in behavior ( e.g., minor or brief avoidance of an area or changes in vocalizations), more conspicuous changes in similar behavioral activities, and more sustained and/or potentially severe reactions, such as displacement from or abandonment of high-quality habitat. Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors ( e.g., species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors ( e.g., Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison et al., 2012), and can vary depending on characteristics associated with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). Please see Appendices B-C of Southall et al. (2007) for a review of studies involving marine mammal behavioral responses to sound. Habituation can occur when an animal's response to a stimulus wanes with repeated exposure, usually in the absence of unpleasant associated events (Wartzok et al., 2003). Animals are most likely to habituate to sounds that are predictable and unvarying. It is important to note that habituation is appropriately considered as a “progressive reduction in response to stimuli that are perceived as neither aversive nor beneficial,” rather than as, more generally, moderation in response to human disturbance (Bejder et al., 2009). The opposite process is sensitization, when an unpleasant experience leads to subsequent responses, often in the form of avoidance, at a lower level of exposure. As noted, behavioral state may affect the type of response. For example, animals that are resting may show greater behavioral change in response to disturbing sound levels than animals that are highly motivated to remain in an area for feeding (Richardson et al., 1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with captive marine mammals have showed pronounced behavioral reactions, including avoidance of loud sound sources (Ridgway et al., 1997; Finneran et al., 2003). Observed responses of wild marine mammals to loud pulsed sound sources (typically airguns or acoustic harassment devices) have been varied but often consist of avoidance behavior or other behavioral changes suggesting discomfort (Morton and Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007). However, many delphinids approach low-frequency airgun source vessels with no apparent discomfort or obvious behavioral change ( e.g., Barkaszi et al., 2012), indicating the importance of frequency output in relation to the species' hearing sensitivity. Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 2005). However, there are broad categories of potential response, which we describe in greater detail here, that include alteration of dive behavior, alteration of foraging behavior, effects to breathing, interference with or alteration of vocalization, avoidance, and flight. Changes in dive behavior can vary widely and may consist of increased or decreased dive times and surface intervals as well as changes in the rates of ascent and descent during a dive ( e.g., Frankel and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et al.; 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior may reflect interruptions in biologically significant activities ( e.g., foraging) or they may be of little biological significance. The impact of an alteration to dive behavior resulting from an acoustic exposure depends on what the animal is doing at the time of the exposure and the type and magnitude of the response. Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance ( e.g., Croll et al., 2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al., 2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal. Variations in respiration naturally vary with different behaviors and alterations to breathing rate as a function of acoustic exposure can be expected to co-occur with other behavioral reactions, such as a flight response or an alteration in diving. However, respiration rates in and of themselves may be representative of annoyance or an acute stress response. Various studies have shown that respiration rates may either be unaffected or could increase, depending on the species and signal characteristics, again highlighting the importance in understanding species differences in the tolerance of underwater noise when determining the potential for impacts resulting from anthropogenic sound exposure ( e.g., Kastelein et al., 2001, 2005, 2006; Gailey et al., 2007; Gailey et al., 2016). Marine mammals vocalize for different purposes and across multiple modes, such as whistling, echolocation click production, calling, and singing. Changes in vocalization behavior in response to anthropogenic noise can occur for any of these modes and may result from a need to compete with an increase in background noise or may reflect increased vigilance or a startle response. For example, in the presence of potentially masking signals, humpback whales and killer whales have been observed to increase the length of their songs (Miller et al., 2000; Fristrup et al., 2003; Foote et al., 2004), while right whales have been observed to shift the frequency content of their calls upward while reducing the rate of calling in areas of increased anthropogenic noise (Parks et al., 2007). In some cases, animals may cease sound production during production of aversive signals (Bowles et al., 1994). Avoidance is the displacement of an individual from an area or migration path as a result of the presence of a sound or other stressors, and is one of the most obvious manifestations of disturbance in marine mammals (Richardson et al., 1995). For example, gray whales are known to change direction—deflecting from customary migratory paths—in order to avoid noise from airgun surveys (Malme et al., 1984). Avoidance may be short-term, with animals returning to the area once the noise has ceased ( e.g., Bowles et al., 1994; Goold, 1996; Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term displacement is possible, however, which may lead to changes in abundance or distribution patterns of the affected species in the affected region if habituation to the presence of the sound does not occur ( e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et al., 2006). A flight response is a dramatic change in normal movement to a directed and rapid movement away from the perceived location of a sound source. The flight response differs from other avoidance responses in the intensity of the response ( e.g., directed movement, rate of travel). Relatively little information on flight responses of marine mammals to anthropogenic signals exist, although observations of flight responses to the presence of predators have occurred (Connor and Heithaus, 1996). The result of a flight response could range from brief, temporary exertion and displacement from the area where the signal provokes flight to, in extreme cases, marine mammal strandings (Evans and England, 2001). However, it should be noted that response to a perceived predator does not necessarily invoke flight (Ford and Reeves, 2008), and whether individuals are solitary or in groups may influence the response. Behavioral disturbance can also impact marine mammals in more subtle ways. Increased vigilance may result in costs related to diversion of focus and attention ( i.e., when a response consists of increased vigilance, it may come at the cost of decreased attention to other critical behaviors such as foraging or resting). These effects have generally not been demonstrated for marine mammals, but studies involving fish and terrestrial animals have shown that increased vigilance may substantially reduce feeding rates ( e.g., Beauchamp and Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In addition, chronic disturbance can cause population declines through reduction of fitness ( e.g., decline in body condition) and subsequent reduction in reproductive success, survival, or both ( e.g., Harrington and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, Ridgway et al. (2006) reported that increased vigilance in bottlenose dolphins exposed to sound over a five-day period did not cause any sleep deprivation or stress effects. Many animals perform vital functions, such as feeding, resting, traveling, and socializing, on a diel cycle (24-hour cycle). Disruption of such functions resulting from reactions to stressors such as sound exposure are more likely to be significant if they last more than one diel cycle or recur on subsequent days (Southall et al., 2007). Consequently, a behavioral response lasting less than one day and not recurring on subsequent days is not considered particularly severe unless it could directly affect reproduction or survival (Southall et al., 2007). Note that there is a difference between multi-day substantive behavioral reactions and multi-day anthropogenic activities. For example, just because an activity lasts for multiple days does not necessarily mean that individual animals are either exposed to activity-related stressors for multiple days or, further, exposed in a manner resulting in sustained multi-day substantive behavioral responses. Stress Responses —An animal's perception of a threat may be sufficient to trigger stress responses consisting of some combination of behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses ( e.g., Seyle, 1950; Moberg, 2000). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness. Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance ( e.g., Moberg, 1987; Blecha, 2000). Increases in the circulation of glucocorticoids are also equated with stress (Romano et al., 2004). The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and “distress” is the cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose serious fitness consequences. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other functions. This state of distress will last until the animal replenishes its energetic reserves sufficient to restore normal function. Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well-studied through controlled experiments and for both laboratory and free-ranging animals ( e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker, 2000; Romano et al., 2002b) and, more rarely, studied in wild populations ( e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as “distress.” In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003). Auditory Masking —Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 2016). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest ( e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities ( e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Under certain circumstances, marine mammals experiencing significant masking could also be impaired from maximizing their performance fitness in survival and reproduction. Therefore, when the coincident (masking) sound is man-made, it may be considered harassment when disrupting or altering critical behaviors. It is important to distinguish TTS and PTS, which persist after the sound exposure, from masking, which occurs during the sound exposure. Because masking (without resulting in TS) is not associated with abnormal physiological function, it is not considered a physiological effect, but rather a potential behavioral effect. The frequency range of the potentially masking sound is important in determining any potential behavioral impacts. For example, low-frequency signals may have less effect on high-frequency echolocation sounds produced by odontocetes but are more likely to affect detection of mysticete communication calls and other potentially important natural sounds such as those produced by surf and some prey species. The masking of communication signals by anthropogenic noise may be considered as a reduction in the communication space of animals ( e.g., Clark et al., 2009) and may result in energetic or other costs as animals change their vocalization behavior ( e.g., Miller et al., 2000; Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt et al., 2009). Masking can be reduced in situations where the signal and noise come from different directions (Richardson et al., 1995), through amplitude modulation of the signal, or through other compensatory behaviors (Houser and Moore, 2014). Masking can be tested directly in captive species ( e.g., Erbe, 2008), but in wild populations it must be either modeled or inferred from evidence of masking compensation. There are few studies addressing real-world masking sounds likely to be experienced by marine mammals in the wild ( e.g., Branstetter et al., 2013). Masking affects both senders and receivers of acoustic signals and can potentially have long-term chronic effects on marine mammals at the population level as well as at the individual level. Low-frequency ambient sound levels have increased by as much as 20 dB (more than three times in terms of SPL) in the world's ocean from pre-industrial periods, with most of the increase from distant commercial shipping (Hildebrand, 2009). All anthropogenic sound sources, but especially chronic and lower-frequency signals ( e.g., from vessel traffic), contribute to elevated ambient sound levels, thus intensifying masking. Potential Effects of Navy Activity —As described previously (see “Description of Active Acoustic Sound Sources”), the Navy proposes to conduct pile driving, including impact and vibratory driving. The effects of pile driving on marine mammals are dependent on several factors, including the size, type, and depth of the animal; the depth, intensity, and duration of the pile driving sound; the depth of the water column; the substrate of the habitat; the standoff distance between the pile and the animal; and the sound propagation properties of the environment. With both types of pile driving, it is likely that the onset of pile driving could result in temporary, short term changes in an animal's typical behavioral patterns and/or avoidance of the affected area. These behavioral changes may include (Richardson et al., 1995): changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where sound sources are located; and/or flight responses. The biological significance of many of these behavioral disturbances is difficult to predict, especially if the detected disturbances appear minor. However, the consequences of behavioral modification could be expected to be biologically significant if the change affects growth, survival, or reproduction. Significant behavioral modifications that could lead to effects on growth, survival, or reproduction, such as drastic changes in diving/surfacing patterns or significant habitat abandonment are extremely unlikely in this area ( i.e., shallow waters in modified industrial areas). The onset of behavioral disturbance from anthropogenic sound depends on both external factors (characteristics of sound sources and their paths) and the specific characteristics of the receiving animals (hearing, motivation, experience, demography) and is difficult to predict (Southall et al., 2007). Whether impact or vibratory driving, sound sources would be active for relatively short durations, with relation to potential for masking. The frequencies output by pile driving activity are lower than those used by most species expected to be regularly present for communication or foraging. We expect insignificant impacts from masking, and any masking event that could possibly rise to Level B harassment under the MMPA would occur concurrently within the zones of behavioral harassment already estimated for vibratory and impact pile driving, and which have already been taken into account in the exposure analysis. Anticipated Effects on Marine Mammal Habitat The proposed activities would not result in permanent impacts to habitats used directly by marine mammals, but may have potential short-term impacts to food sources such as forage fish. The proposed activities could also affect acoustic habitat (see masking discussion above), but meaningful impacts are unlikely. There are no known foraging hotspots, or other ocean bottom structures of significant biological importance to marine mammals present in the marine waters in the vicinity of the project areas. Therefore, the main impact issue associated with the proposed activity would be temporarily elevated sound levels and the associated direct effects on marine mammals, as discussed previously in this preamble. The most likely impact to marine mammal habitat occurs from pile driving effects on likely marine mammal prey ( i.e., fish) near the six installations. Impacts to the immediate substrate during installation and removal of piles are anticipated, but these would be limited to minor, temporary suspension of sediments, which could impact water quality and visibility for a short amount of time, but which would not be expected to have any effects on individual marine mammals. Impacts to substrate are therefore not discussed further. Effects to Prey —Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies by species, season, and location and, for some, is not well documented. Here, we describe studies regarding the effects of noise on known marine mammal prey. Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning ( e.g., Zelick et al., 1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality. Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation ( e.g., feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish, although several are based on studies in support of large, multiyear bridge construction projects ( e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al., 2017). However, some studies have shown no or slight reaction to impulse sounds ( e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). More commonly, though, the impacts of noise on fish are temporary. SPLs of sufficient strength have been known to cause injury to fish and fish mortality. However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen et al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013). The most likely impact to fish from pile driving activities at the project areas would be temporary behavioral avoidance of the area. The duration of fish avoidance of an area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution and behavior is anticipated. In general, impacts to marine mammal prey species are expected to be minor and temporary due to the expected short daily duration of individual pile driving events and the relatively small areas being affected. It is also not expected that the industrial environment of the Naval installations provides important fish habitat or harbors significant amounts of forage fish. The area likely impacted by the activities is relatively small compared to the available habitat in inland waters in the region. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. As described in the preceding, the potential for Navy construction to affect the availability of prey to marine mammals or to meaningfully impact the quality of physical or acoustic habitat is considered to be insignificant. Effects to habitat will not be discussed further in this document. Estimated Take This section provides an estimate of the number of incidental takes proposed for authorization, which will inform both NMFS's consideration of whether the number of takes is “small” and the negligible impact determination. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as: Any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment). Take of marine mammals incidental to Navy construction activities could occur as a result of Level A or Level B harassment. Below we describe how the potential take is estimated. 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 exhibit behavioral disruptions (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment). Level B Harassment —Although available data are consistent with the basic concept that louder sounds evoke more significant behavioral responses than softer sounds, defining sound levels that disrupt behavioral patterns is difficult because responses depend on the context in which the animal receives the sound, including an animal's behavioral mode when it hears sounds ( e.g., feeding, resting, or migrating), prior experience, and biological factors ( e.g., age and sex). Some species, such as beaked whales, are known to be more highly sensitive to certain anthropogenic sounds than other species. Other contextual factors, such as signal characteristics, distance from the source, and signal to noise ratio, may also help determine response to a given received level of sound. Therefore, levels at which responses occur are not necessarily consistent and can be difficult to predict (Southall et al., 2007; Ellison et al., 2012; Bain and Williams, 2006). However, based on the practical need to use a relatively simple threshold based on available information that is both predictable and measurable for most activities, NMFS has historically used a generalized acoustic threshold based on received level to estimate the onset of Level B harassment. These thresholds are 160 dB rms (impulsive sources) and 120 dB rms (continuous sources). Level A Harassment —NMFS's Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (NMFS, 2016) identifies dual criteria to assess the potential for auditory injury (Level A harassment) to occur for different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise. The technical guidance identifies the received levels, or thresholds, above which individual marine mammals are predicted to experience changes in their hearing sensitivity for all underwater anthropogenic sound sources, and reflects the best available science on the potential for noise to affect auditory sensitivity by: • Dividing sound sources into two groups ( i.e., impulsive and non-impulsive) based on their potential to affect hearing sensitivity; • Choosing metrics that best address the impacts of noise on hearing sensitivity, i.e., peak sound pressure level (peak SPL) (reflects the physical properties of impulsive sound sources to affect hearing sensitivity) and cumulative sound exposure level (cSEL) (accounts for not only level of exposure but also duration of exposure); and • Dividing marine mammals into hearing groups and developing auditory weighting functions based on the science supporting that not all marine mammals hear and use sound in the same manner. The premise of the dual criteria approach is that, while there is no definitive answer to the question of which acoustic metric is most appropriate for assessing the potential for injury, both the received level and duration of received signals are important to an understanding of the potential for auditory injury. Therefore, peak SPL is used to define a pressure criterion above which auditory injury is predicted to occur, regardless of exposure duration ( i.e., any single exposure at or above this level is considered to cause auditory injury), and cSEL is used to account for the total energy received over the duration of sound exposure ( i.e., both received level and duration of exposure) (Southall et al., 2007; NMFS, 2016). As a general principle, whichever criterion is exceeded first ( i.e., results in the largest isopleth) would be used as the effective injury criterion ( i.e., the more precautionary of the criteria). Note that cSEL acoustic threshold levels incorporate marine mammal auditory weighting functions, while peak pressure thresholds do not ( i.e., flat or unweighted). Weighting functions for each hearing group ( e.g., low-, mid-, and high-frequency cetaceans) are described in NMFS (2016). NMFS (2016) recommends 24 hours as a maximum accumulation period relative to cSEL thresholds. These thresholds were developed by compiling and synthesizing the best available science, and are provided in Table 3 below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS (2016), which is available online at: www.nmfs.noaa.gov/pr/acoustics/guidelines.htm. Table 3—Exposure Criteria for Auditory Injury Hearing group Peak pressure 1 (dB) Cumulative sound exposure level 2 Impulsive (dB) Non-impulsive (dB) Low-frequency cetaceans 219 183 199 Mid-frequency cetaceans 230 185 198 High-frequency cetaceans 202 155 173 Phocid pinnipeds 218 185 201 Otariid pinnipeds 232 203 219 1 Referenced to 1 μPa; unweighted within generalized hearing range. 2 Referenced to 1 μPa 2 -s; weighted according to appropriate auditory weighting function. Zones of Ensonification Sound Propagation —Transmission loss (TL) is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is: TL = B * log 10 (R 1 /R 2 ) Where: B = transmission loss coefficient (assumed to be 15) R 1 = the distance of the modeled SPL from the driven pile, and R 2 = the distance from the driven pile of the initial measurement. This formula neglects loss due to scattering and absorption, which is assumed to be zero here. The degree to which underwater sound propagates away from a sound source is dependent on a variety of factors, most notably the water bathymetry and presence or absence of reflective or absorptive conditions including in-water structures and sediments. Spherical spreading occurs in a perfectly unobstructed (free-field) environment not limited by depth or water surface, resulting in a 6 dB reduction in sound level for each doubling of distance from the source (20 * log(range)). Cylindrical spreading occurs in an environment in which sound propagation is bounded by the water surface and sea bottom, resulting in a reduction of 3 dB in sound level for each doubling of distance from the source (10 * log(range)). As is common practice in coastal waters, here we assume practical spreading loss (4.5 dB reduction in sound level for each doubling of distance). Practical spreading is a compromise that is often used under conditions where water depth increases as the receiver moves away from the shoreline, resulting in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions. Sound Source Levels —The intensity of pile driving sounds is greatly influenced by factors such as the type of piles, hammers, and the physical environment in which the activity takes place. There are source level measurements avai [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2018-04148. Public record. Not legal advice.