86 FR 212 pgs. 61164-61181 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Falls Bridge Replacement Project in Blue Hill, Maine
Type: NOTICEVolume: 86Number: 212Pages: 61164 - 61181
Pages: 61164, 61165, 61166, 61167, 61168, 61169, 61170, 61171, 61172, 61173, 61174, 61175, 61176, 61177, 61178, 61179, 61180, 61181Docket number: [RTID 0648- XB546]
FR document: [FR Doc. 2021-24164 Filed 11-4-21; 8:45 am]
Agency: Commerce Department
Sub Agency: National Oceanic and Atmospheric Administration
Official PDF Version: PDF Version
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648- XB546]
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Falls Bridge Replacement Project in Blue Hill, Maine
AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION:
Notice; proposed incidental harassment authorization; request for comments on proposed authorization and possible renewal.
SUMMARY:
NMFS has received a request from the Maine Department of Transportation (MEDOT) for authorization to take marine mammals incidental to the Falls Bridge Replacement Project in Blue Hill, Maine. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this document. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorizations and agency responses will be summarized in the final notice of our decision.
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DATES:
Comments and information must be received no later than December 6, 2021.
ADDRESSES:
Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service and should be sent to ITP.Meadows@noaa.gov.
Instructions: NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments received electronically, including all attachments, must not exceed a 25-megabyte file size. Attachments to electronic comments will be accepted in Microsoft Word or Excel or Adobe PDF file formats only. All comments received are a part of the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying information ( e.g., name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT:
Dwayne Meadows, Ph.D., Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these documents, please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the "take" of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq. ) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed incidental take authorization may be provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other "means of effecting the least practicable adverse impact" on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as "mitigation"); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth.
The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321 et seq. ) and NOAA Administrative Order (NAO) 216-6A, NMFS must review our proposed action ( i.e., the issuance of an IHA) with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified in Categorical Exclusion B4 (IHAs with no anticipated serious injury or mortality) of the Companion Manual for NOAA Administrative Order 216-6A, which do not individually or cumulatively have the potential for significant impacts on the quality of the human environment and for which we have not identified any extraordinary circumstances that would preclude this categorical exclusion. Accordingly, NMFS has preliminarily determined that the issuance of the proposed IHA qualifies to be categorically excluded from further NEPA review.
We will review all comments submitted in response to this document prior to concluding our NEPA process or making a final decision on the IHA request.
Summary of Request
On October 7, 2021, NMFS received an application from MEDOT requesting an IHA to take small numbers of seven species (harbor seal ( Phoca vitulina ), gray seal ( Halichoerus grypus ), harp seal ( Pagophilus groenlandicus ), hooded seal ( Cystophora cristata ), harbor porpoise ( Phocoena phocoena ), Atlantic white-sided dolphin ( Lagenorhynchus acutus ) and common dolphin ( Delphinus delphis )) of marine mammals incidental to pile driving and removal associated with the project. The application was deemed adequate and complete on October 20, 2021. MEDOT's request is for take of a small number of these species by Level B harassment and a small amount of Level A harassment take for harbor seals. Neither MEDOT nor NMFS expects serious injury or mortality to result from this activity and, therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
The purpose of the project is to address the structural deficiency of the Falls Bridge and improve public safety. In-water pile driving is needed to create temporary work trestles and support towers and a temporary bridge for vehicle traffic during construction. The work in this application involves the installation of up to 95 24-inch diameter steel piles and then the removal of all piles at the conclusion of the project. The project will take no more than 80 days of in-water pile work.
The pile driving/removal can result in take of marine mammals from sound in the water which may result in behavioral harassment or auditory injury.
Dates and Duration
The IHA is proposed to be effective for one year from July 1, 2022 through June 30, 2023. Exact start dates may change depending on completion of contracting and other environmental compliance, but the IHA will be valid for one year.
Specific Geographic Region
The project is located in the town of Blue Hill, Maine, approximately 28 miles (45 kilometers) southeast of Bangor. The Falls Bridge carries State Route 175 over the Salt Pond Outlet (Figure 1). The Falls Bridge provides the principal opening between the Salt Pond, a one square mile (2.59 square kilometer (km)) tidal estuary, and the Atlantic Ocean. With each tidal cycle a significant volume of water passes through the bridge opening, generating high flow velocities and a "hydraulic jump" during mid-tide periods that is colloquially referred to as the reversing falls. The reversing falls, the Falls Bridge itself, and the natural beauty of the area has caused the Falls Bridge to become a destination for sightseers, nature enthusiasts, and recreationists.
BILLING CODE 4910-81-P
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[Federal Register graphic "EN05NO21.034" is not available. Please view the graphic in the PDF version of this document.]
BILLING CODE 4910-81-C
The Falls Bridge lies on the transition between an estuarine unconsolidated bottom subtidal system associated with the Salt Pond to the west, and a marine unconsolidated bottom subtidal system associated with Blue Hill Bay to the east. Where the transition occurs, immediately under the bridge and a few hundred feet into Blue Hill Bay, lies a small strip of marine intertidal rocky shore (bedrock dominated). Salinity in the area ranges from 25-35 parts per million, water depth is 0 to 50 feet (0 to 15.2 meters (m)), and water temperature ranges from 38 to 58 degrees Fahrenheit. Ongoing small vessel and recreation/commercial activities ( e.g., lobster fishing, sea urchin harvest, sea duck hunting) in Blue Hill Bay likely result in elevated in-air and underwater sound conditions intermittently throughout the year. Background sound levels likely vary seasonally, with the greatest amount of in-air noise associated with the tourism during the summer months, and fishing/hunting activities during late fall and early winter months.
Detailed Description of Specific Activity
[top] The project consists of creating a temporary bridge for vehicle traffic during work on the Falls Bridge; this will require the installation (and then removal when the project is complete) of 15 24-inch steel pipe piles. Work on the main bridge deck is not expected to incidentally harass marine mammals, however in order to facilitate that work, one or two large trestles (up to 100 foot by 125 foot (30.5 by 38 m) long) would be placed in the water next to the bridge. These trestles would require the installation of up to 60 24-inch diameter
In total then the project involves installation and removal of 95 24-inch diameter steel pipe piles. It is expected that all 95 piles will be installed in rock sockets (holes) in the bedrock created by down-the-hole (DTH) equipment. Impact pile driving will be used to seat the piles and potentially drive them through softer substrates. For piles driven in the center of the channel under the bridge (mostly for the trestles), additional lateral stability may require the use of rebar tension anchors drilled deeper into the substrate in the center of the piles and connected to the piles once installed. This would be accomplished by using an 8-inch diameter DTH bit. It is expected that no more than 65 of the 95 piles would require these tension anchors. Once the work on the bridge is complete all 95 piles will be removed using a vibratory hammer.
The DTH and impact hammer installation and vibratory extraction of the piles is expected to take up to 80 days of in-water work. These actions could produce underwater sound at levels that could result in the injury or behavioral harassment of marine mammal species.
Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please see Proposed Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history, of the potentially affected species. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS's website ( https://www.fisheries.noaa.gov/find-species ).
Table 1 lists all species with expected potential for occurrence in the project area and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. For taxonomy, we follow Committee on Taxonomy (2021). PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS's SARs). While no mortality is anticipated or authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species and other threats.
Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS's 2021 U.S. Atlantic Draft SARs ( e.g., Hayes et al., 2021).
| 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 Odontoceti (toothed whales, dolphins, and porpoises) | ||||||
| Family Delphinidae: | ||||||
| Atlantic white-sided dolphin | Lagenorhynchus acutus | Western North Atlantic | -, -; N | 93,233 (0.71, 54,443, See SAR) | 544 | 26 |
| Common dolphin | Delphinus delphis | Western North Atlantic | -, -; N | 172,8974 (0.21, 145,216, 2016) | 1452 | 399 |
| Family Phocoenidae (porpoises): | ||||||
| Harbor porpoise | Phocoena phocoena | Gulf of Maine/Bay of Fundy | -, -; N | 95,543 (0.31; 74,034; 2016) | 851 | 217 |
| Order Carnivora-Superfamily Pinnipedia | ||||||
| Family Phocidae (earless seals): | ||||||
| Harbor seal | Phoca vitulina | Western North Atlantic | -; N | 61,336 (0.08; 57,637, 2018) | 1,729 | 339 |
| Gray seal? 4 | Halichoerus grypus | Western North Atlantic | -; N | 27,300 (0.22, 22,785, 2018) | 1,389 | 4,453 |
| Harp seal | Pagophilus groenlandicus | Western North Atlantic | -; N | 7,600,000 (UNK, 7,100,000, 2019) | 426,000 | 178,573 |
| Hooded seal | Cystophora cristata | Western North Atlantic | -; N | UNK (UNK, UNK, See SAR) | UNK | 1,680 |
| 1 ?Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. | ||||||
| 2 ?NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; N min is the minimum estimate of stock abundance. | ||||||
| 3 ?These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, ship strike). Annual Mortality/Serious Injury (M/SI) often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. | ||||||
| 4 ?The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 505,000. The PBR value is estimated for the U.S. population, while the M/SI estimate is provided for the entire gray seal stock (including animals in Canada). | ||||||
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Harbor seal, gray seal, harbor porpoise, Atlantic white-sided dolphin and common dolphin spatially co-occur with the activity to the degree that take is reasonably likely to occur, and we have proposed authorizing take of these species. Harp seal and hooded seal are rare in the project area but could occur and we have proposed authorizing take of these species. All species that could potentially occur in the proposed survey areas are included in the MEDOT's IHA application (see application, Section 3). Humpback whale, North Atlantic right whale, minke whale, sei whale and fin whale could potentially occur in the area. However the spatial and temporal occurrence of these species is very rare, typically further offshore, the species are readily observed, and the applicant would shut down pile driving if they enter the project area (see Proposed Monitoring and Reporting section). Thus take is not expected to occur, and they are not discussed further.
The best available data for marine mammal presence in the vicinity of the project is the result of monitoring surveys completed in preparation for the project. The Shaw Institute (formerly Marine and Environmental Research Institute) was contracted by MEDOT to provide baseline data on seasonal marine mammal observations near the Falls Bridge. Surveys took place on 74 days from June 27, 2017 to July 24, 2018.
Atlantic White-Sided Dolphin
White-sided dolphins occur in temperate and sub-polar waters of the North Atlantic, primarily in continental shelf waters to the 100-m depth contour from central West Greenland to North Carolina (Waring et al., 2019). The Gulf of Maine stock is most common in continental shelf waters from Hudson Canyon to Georges Bank, and in the Gulf of Maine and lower Bay of Fundy. Sighting data indicate seasonal shifts in distribution (Northridge et al., 1997). During January to May, low numbers of white-sided dolphins are found from Georges Bank to Jeffreys Ledge (off New Hampshire), with even lower numbers south of Georges Bank. From June through September, large numbers of white-sided dolphins are found from Georges Bank to the lower Bay of Fundy. From October to December, white-sided dolphins occur at intermediate densities from southern Georges Bank to southern Gulf of Maine (Payne and Heinemann, 1990). This species moves closer inshore in the summers and offshore in the winters.
Common Dolphin
The common dolphin occurs world-wide in temperate to subtropical seas. In the North Atlantic, common dolphins commonly occur over the continental shelf between the 100-m and 2,000-m isobaths and over prominent underwater topography and east to the mid-Atlantic Ridge (Waring et al., 2019). This species is found between Cape Hatteras and Georges Bank from mid-January to May, although they migrate onto the northeast edge of Georges Bank in the fall where large aggregations occur (Kenney and Vigness-Raposa, 2009).
Harbor Porpoise
The harbor porpoise is typically found in colder waters in the northern hemisphere. In the western North Atlantic Ocean, harbor porpoises range from Greenland to as far south as North Carolina (Barco and Swingle, 2014). They are commonly found in bays, estuaries, and harbors less than 200 meters deep (NOAA Fisheries, 2016c). Harbor porpoises in the United States are made up of the Gulf of Maine/Bay of Fundy stock. Gulf of Maine/Bay of Fundy stock are concentrated in the Gulf of Maine in the summer, but are widely dispersed from Maine to New Jersey in the winter. South of New Jersey, harbor porpoises occur at lower densities. Migrations to and from the Gulf of Maine do not follow a defined route (NOAA Fisheries, 2016c).
In most areas, harbor porpoise occur in small groups of just a few individuals. There were 7 harbor porpoise sighted by the Shaw team (Shaw Institute, 2018).
Harbor Seal
The harbor seal occurs in arctic and temperate coastal waters throughout the northern hemisphere, including on both the east and west coasts of the United States. On the east coast, harbor seals can be found from the Canadian Arctic down to Georgia (Blaylock, 1985). Harbor seals occur year-round in Canada and Maine and seasonally (September-May) from southern New England to New Jersey (NOAA Fisheries, 2016d). The range of harbor seals appears to be shifting as they are regularly reported further south than they were historically.
Harbor seals are central-place foragers (Orians and Pearson, 1979) and tend to exhibit strong site fidelity within season and across years, generally forage close to haulout sites, and repeatedly visit specific foraging areas (Suryan and Harvey, 1998; Thompson et al., 1998). Harbor seals tend to forage at night and haul out during the day with a peak in the afternoon between 1 p.m. and 4 p.m. (London et al., 2001).
Harbor seals were the most common marine mammal observed by the Shaw team near Falls Bridge, making up 89 percent of the marine mammals observed (Shaw Institute, 2018).
Gray Seal
The gray seal occurs on both coasts of the Northern Atlantic Ocean and are divided into three major populations (NOAA Fisheries 2016b). The western north Atlantic stock occurs in eastern Canada and the northeastern United States, occasionally as far south as North Carolina. Gray seals inhabit rocky coasts and islands, sandbars, ice shelves and icebergs (NOAA Fisheries 2016b). In the United States, gray seals congregate in the summer to give birth at four established colonies in Massachusetts and Maine (NOAA Fisheries 2016b). From September through May, they disperse and can be abundant as far south as New Jersey. The range of gray seals appears to be shifting as they are regularly being reported further south than they were historically (Rees et al. 2016). There was 1 gray seal observed by the Shaw team near the bridge (Shaw Institute 2018).
Harp Seal
The harp seal is a highly migratory species, its range extending throughout the Arctic and North Atlantic Oceans. The world's harp seal population is separated into three stocks, based on associations with specific locations of breeding activities: (1) Off eastern Canada, (2) on the West Ice off eastern Greenland, and (3) in the White Sea off the coast of Russia. The largest stock, which includes two herds that breed either off the coast of Newfoundland/Labrador or near the Magdelan Islands in the Gulf of St. Lawrence, is equivalent to the western North Atlantic stock under the MMPA. The best estimate of abundance for western North Atlantic harp seals, based on the last survey (in 2012) is 7.4 million, with a minimum estimate of 6.9 million (Waring et al., 2020). In U.S. waters, the species has an increasing presence since the 1990s, evidenced by increasing numbers of sightings and strandings in the coastal waters between Maine and New Jersey (Waring et al., 2020). Harp seals that occur in the United States generally occur in New England waters from January through May (Waring et al., 2020).
Hooded Seal
[top] Hooded seals are generally found in deeper waters or on drifting pack ice.
Population abundance of hooded seals in the western North Atlantic is derived from pup production estimates, which are developed from whelping pack surveys. The most recent population estimate in the western North Atlantic was derived in 2005. There have been no recent surveys conducted or population estimates developed for this species. The 2005 best population estimate for hooded seals is 593,500 individuals, with a minimum population estimate of 543,549 individuals (Waring et al., 2019). Currently, not enough data are available to determine what percentage of this estimate may represent the population within U.S. waters.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 2.
| Hearing group | Generalized hearing range?* |
|---|---|
| Low-frequency (LF) cetaceans (baleen whales) | 7 Hz to 35 kHz. |
| Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) | 150 Hz to 160 kHz. |
| High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L. australis ) | 275 Hz to 160 kHz. |
| Phocid pinnipeds (PW) (underwater) (true seals) | 50 Hz to 86 kHz. |
| Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) | 60 Hz to 39 kHz. |
| *?Represents the generalized hearing range for the entire group as a composite ( i.e., all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall et al., 2007) and PW pinniped (approximation). | |
The pinniped functional hearing group was modified from Southall et al. (2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemilä et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 2013).
For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. The baleen whales are in the low-frequency hearing group, the dolphins are in the mid-frequency hearing group, harbor porpoises are in the high frequency hearing group, and the seals are in the phocid group.
Potential Effects of Specified Activities on Marine Mammals and Their Habitat
This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.
Acoustic effects on marine mammals during the specified activity can occur from impact and vibratory pile driving and removal and DTH. The effects of underwater noise from MEDOT's proposed activities have the potential to result in Level A or Level B harassment of marine mammals in the action area.
Description of Sound Sources
The marine soundscape is comprised of both ambient and anthropogenic sounds. Ambient sound is defined as the all-encompassing sound in a given place and is usually a composite of sound from many sources both near and far (ANSI 1995). The sound level of an area is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical ( e.g., waves, wind, precipitation, earthquakes, ice, atmospheric sound), biological ( e.g., sounds produced by marine mammals, fish, and invertebrates), and anthropogenic sound ( e.g., vessels, dredging, aircraft, construction).
[top] The sum of the various natural and anthropogenic sound sources at any given location and time-which comprise "ambient" or "background" sound-depends not only on the source levels (as determined by current weather conditions and levels of
In-water construction activities associated with the project would include impact and vibratory pile driving and removal and DTH. The sounds produced by these activities fall into one of two general sound types: Impulsive and non-impulsive. Impulsive sounds ( e.g., explosions, gunshots, sonic booms, impact pile driving) are typically transient, brief (less than 1 second), broadband, and consist of high peak sound pressure with rapid rise time and rapid decay (ANSI, 1986; NIOSH, 1998; NMFS, 2018). Non-impulsive sounds ( e.g., machinery operations such as drilling or dredging, vibratory pile driving, underwater chainsaws, pile clippers, and active sonar systems) can be broadband, narrowband or tonal, brief or prolonged (continuous or intermittent), and typically do not have the high peak sound pressure with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward 1997 in Southall et al., 2007).
Three types of pile hammers would be used on this project: Impact, vibratory, and DTH. Impact hammers operate by repeatedly dropping and/or pushing a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is characterized by rapid rise times and high peak levels, a potentially injurious combination (Hastings and Popper, 2005). Vibratory hammers install piles by vibrating them and allowing the weight of the hammer to push them into the sediment. Vibratory hammers produce significantly less sound than impact hammers. Peak Sound pressure Levels (SPLs) may be 180 dB or greater, but are generally 10 to 20 dB lower than SPLs generated during impact pile driving of the same-sized pile (Oestman et al., 2009). Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time (Nedwell and Edwards, 2002; Carlson et al., 2005).
A DTH hammer is essentially a drill bit that drills through the bedrock using a rotating function like a normal drill, in concert with a hammering mechanism operated by a pneumatic (or sometimes hydraulic) component integrated into to the DTH hammer to increase speed of progress through the substrate ( i.e., it is similar to a "hammer drill" hand tool). Rock socketing involves using DTH equipment to create a hole in the bedrock inside which the pile is placed to give it lateral and longitudinal strength. Tension anchoring involves creating a smaller hole inside and deeper than the rock socket. A long piece of rebar is inserted in this hole, grouted or cemented in place, and then the top of the rebar is connected to the top of the pile to increase pile stability. The sounds produced by the DTH method contain both a continuous, non-impulsive component from the drilling action and an intermittent, impulsive component from the hammering effect. Therefore, we treat DTH systems as both intermittent, impulsive (for Level A thresholds) and continuous, non-impulsive (for Level B thresholds) sound source types simultaneously.
The likely or possible impacts of MEDOT's proposed activity on marine mammals could involve both non-acoustic and acoustic stressors. Potential non-acoustic stressors could result from the physical presence of the equipment, vessels, and personnel; however, any impacts to marine mammals are expected to primarily be acoustic in nature. Acoustic stressors include effects of heavy equipment operation during pile installation and removal.
Acoustic Impacts
The introduction of anthropogenic noise into the aquatic environment from pile driving equipment is the primary means by which marine mammals may be harassed from the MEDOT's specified activity. In general, animals exposed to natural or anthropogenic sound may experience physical and psychological effects, ranging in magnitude from none to severe (Southall et al., 2007). Generally, exposure to pile driving and removal and other construction noise has the potential to result in auditory threshold shifts and behavioral reactions ( e.g., avoidance, temporary cessation of foraging and vocalizing, changes in dive behavior). Exposure to anthropogenic noise can also lead to non-observable physiological responses such an increase in stress hormones. Additional noise in a marine mammal's habitat can mask acoustic cues used by marine mammals to carry out daily functions such as communication and predator and prey detection. The effects of pile driving and demolition noise on marine mammals are dependent on several factors, including, but not limited to, sound type ( e.g., impulsive vs. non-impulsive), the species, age and sex class ( e.g., adult male vs. mom with calf), duration of exposure, the distance between the pile and the animal, received levels, behavior at time of exposure, and previous history with exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss physical auditory effects (threshold shifts) followed by behavioral effects and potential impacts on habitat.
NMFS defines a noise-induced threshold shift (TS) as a change, usually an increase, in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). The amount of threshold shift is customarily expressed in dB. A TS can be permanent or temporary. As described in NMFS (2018), there are numerous factors to consider when examining the consequence of TS, including, but not limited to, the signal temporal pattern ( e.g., impulsive or non-impulsive), likelihood an individual would be exposed for a long enough duration or to a high enough level to induce a TS, the magnitude of the TS, time to recovery (seconds to minutes or hours to days), the frequency range of the exposure ( i.e., spectral content), the hearing and vocalization frequency range of the exposed species relative to the signal's frequency spectrum ( i.e., how animal uses sound within the frequency band of the signal; e.g., Kastelein et al., 2014), and the overlap between the animal and the source ( e.g., spatial, temporal, and spectral).
[top] Permanent Threshold Shift (PTS) -NMFS defines PTS as a permanent, irreversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Available data from humans and other terrestrial mammals indicate that a 40 dB threshold shift approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson and Hu, 2008). PTS levels for marine mammals are
Temporary Threshold Shift (TTS) -A temporary, reversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS, 2018). Based on data from cetacean TTS measurements (see Southall et al., 2007), a TTS of 6 dB is considered the minimum threshold shift clearly larger than any day-to-day or session-to-session variation in a subject's normal hearing ability (Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in Finneran (2016), marine mammal studies have shown the amount of TTS increases with cumulative sound exposure level (SEL cum ) in an accelerating fashion: At low exposures with lower SEL cum , the amount of TTS is typically small and the growth curves have shallow slopes. At exposures with higher SEL cum , the growth curves become steeper and approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during time when communication is critical for successful mother/calf interactions could have more serious impacts. We note that reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall et al., 2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without cost.
Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin, beluga whale ( Delphinapterus leucas ), harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis )) and five species of pinnipeds exposed to a limited number of sound sources ( i.e., mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). TTS was not observed in trained spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran, 2015). The potential for TTS from impact pile driving exists. After exposure to playbacks of impact pile driving sounds (rate 2760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 minute exposure to 5 dB after 360 minute exposure; recovery occurred within 60 minutes (Kastelein et al., 2016). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. No data are available on noise-induced hearing loss for mysticetes. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall et al. (2007), Finneran and Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018).
Installing piles for this project requires impact pile driving and DTH. There would likely be pauses in activities producing the sound during each day. Given these pauses and that many marine mammals are likely moving through the action area and not remaining for extended periods of time, the potential for TS declines.
Behavioral Harassment -Exposure to noise from pile driving and removal also has the potential to behaviorally disturb marine mammals. Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, l et al one the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 2005).
Disturbance may result in changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where sound sources are located. Pinnipeds may increase their haul out time, possibly to avoid in-water disturbance (Thorson and Reyff, 2006). Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors ( e.g., species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors ( e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al., 2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison et al., 2012), and can vary depending on characteristics associated with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). In general, pinnipeds seem more tolerant of, or at least habituate more quickly to, potentially disturbing underwater sound than do cetaceans, and generally seem to be less responsive to exposure to industrial sound than most cetaceans. Please see Appendices B and C of Southall et al. (2007) for a review of studies involving marine mammal behavioral responses to sound.
Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance ( e.g., Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal.
[top] In 2016, the Alaska Department of Transportation and Public Facilities (ADOT&PF) documented observations
Stress responses -An animal's perception of a threat may be sufficient to trigger stress responses consisting of some combination of behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses ( e.g., Seyle 1950; Moberg 2000). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress-including immune competence, reproduction, metabolism, and behavior-are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance ( e.g., Moberg 1987; Blecha 2000). Increases in the circulation of glucocorticoids are also equated with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and "distress" is the cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose serious fitness consequences. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other functions. This state of distress will last until the animal replenishes its energetic reserves sufficient to restore normal function.
Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well-studied through controlled experiments and for both laboratory and free-ranging animals ( e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker 2000; Romano et al., 2002b) and, more rarely, studied in wild populations ( e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as "distress." In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003), however distress is an unlikely result of this project based on observations of marine mammals during previous, similar projects in the area.
Masking -Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., pile driving, shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest ( e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities ( e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Masking of natural sounds can result when human activities produce high levels of background sound at frequencies important to marine mammals. Conversely, if the background level of underwater sound is high ( e.g., on a day with strong wind and high waves), an anthropogenic sound source would not be detectable as far away as would be possible under quieter conditions and would itself be masked. The project area contains active commercial shipping, as well as numerous recreational and other commercial vessel and background sound levels in the area are already elevated.
Airborne Acoustic Effects -Pinnipeds that occur near the project site could be exposed to airborne sounds associated with pile driving and removal that have the potential to cause behavioral harassment, depending on their distance from pile driving activities. Cetaceans are not expected to be exposed to airborne sounds that would result in harassment as defined under the MMPA.
[top] Airborne noise would primarily be an issue for pinnipeds that are swimming or hauled out near the project site within the range of noise levels elevated above the acoustic criteria. There are no known haulouts in the project vicinity. We recognize that pinnipeds in the water could be exposed to airborne sound that may result in behavioral harassment when looking with their heads above water. Most likely, airborne sound would cause behavioral responses similar to those discussed above in relation to underwater sound. For instance, anthropogenic sound could cause hauled out pinnipeds to exhibit changes in their normal behavior, such as reduction in vocalizations, or cause them to temporarily abandon the area and move further from the source. However, these animals would likely previously have been `taken' because of exposure to underwater sound above the behavioral harassment thresholds, which are generally larger than those associated
Marine Mammal Habitat Effects
MEDOT's construction activities could have localized, temporary impacts on marine mammal habitat and their prey by increasing in-water sound pressure levels and slightly decreasing water quality. Increased noise levels may affect acoustic habitat (see masking discussion above) and adversely affect marine mammal prey in the vicinity of the project area (see discussion below). During DTH, impact and vibratory pile driving or removal, elevated levels of underwater noise would ensonify the project area where both fishes and mammals occur and could affect foraging success. Additionally, marine mammals may avoid the area during construction, however, displacement due to noise is expected to be temporary and is not expected to result in long-term effects to the individuals or populations. Construction activities are of short duration and would likely have temporary impacts on marine mammal habitat through increases in underwater and airborne sound.
A temporary and localized increase in turbidity near the seafloor would occur in the immediate area surrounding the area where piles are installed or removed. In general, turbidity associated with pile installation is localized to about a 25-foot (7.6-m) radius around the pile (Everitt et al., 1980). The sediments of the project site are sandy and will settle out rapidly when disturbed. Cetaceans are not expected to be close enough to the pile driving areas to experience effects of turbidity, and any pinnipeds could avoid localized areas of turbidity. Local strong currents are anticipated to disburse any additional suspended sediments produced by project activities at moderate to rapid rates depending on tidal stage. Therefore, we expect the impact from increased turbidity levels to be discountable to marine mammals and do not discuss it further.
In-Water Construction Effects on Potential Foraging Habitat
The area likely impacted by the project is relatively small compared to the available habitat. The project area does not include any Biologically Important Areas or other habitat of known importance. The area is highly influenced by anthropogenic activities. The total seafloor area affected by pile installation and removal is a small area compared to the vast foraging area available to marine mammals in the area. At best, the impact area provides marginal foraging habitat for marine mammals and fishes. Furthermore, pile driving and removal at the project site would not obstruct movements or migration of marine mammals.
Avoidance by potential prey ( i.e., fish) of the immediate area due to the temporary loss of this foraging habitat is also possible. The duration of fish avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution and behavior is anticipated. 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.
In-water Construction Effects on Potential Prey -Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies by species, season, and location. Here, we describe studies regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning ( e.g., Zelick and Mann, 1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.
Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation ( e.g., feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish; several are based on studies in support of large, multiyear bridge construction projects ( e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 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).
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 and removal and construction activities at the project area would be temporary behavioral avoidance of the area. The duration of fish avoidance of this area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution and behavior is anticipated.
Construction activities, in the form of increased turbidity, have the potential to adversely affect forage fish in the project area. Forage fish form a significant prey base for many marine mammal species that occur in the project area. Increased turbidity is expected to occur in the immediate vicinity (on the order of 10 feet (3 m) or less) of construction activities. However, suspended sediments and particulates are expected to dissipate quickly within a single tidal cycle. Given the limited area affected and high tidal dilution rates any effects on forage fish are expected to be minor or negligible.
[top] In summary, given the short daily duration of sound associated with individual pile driving events and the relatively small areas being affected,
Estimated Take
This section provides an estimate of the number of incidental takes proposed for authorization through this IHA, which will inform both NMFS' consideration of "small numbers" and the negligible impact determination.
Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines "harassment" as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use of the acoustic sources has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for Level A harassment to result, primarily for phocids because predicted auditory injury zones are larger than for other groups and harbor seals are common. Auditory injury is unlikely to occur for other species/groups. The proposed mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. As described previously, no mortality is anticipated or proposed to be authorized for this activity. Below we describe how the take is estimated.
Generally speaking, we estimate take by considering: (1) Acoustic thresholds above which marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and, (4) and the number of days of activities. We note that while these basic factors can contribute to a basic calculation to provide an initial prediction of takes, additional information that can qualitatively inform take estimates is also sometimes available ( e.g., previous monitoring results or average group size). Due to the lack of marine mammal density data available for this location, NMFS relied on local occurrence data and group size to estimate take for some species. Below, we describe the factors considered here in more detail and present the proposed take estimate.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment).
Level B Harassment for non-explosive sources -Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source ( e.g., frequency, predictability, duty cycle), the environment ( e.g., bathymetry), and the receiving animals (hearing, motivation, experience, demography, behavioral context) and can be difficult to predict (Southall et al., 2007, Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a factor that is both predictable and measurable for most activities, NMFS uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS predicts that marine mammals are likely to be behaviorally harassed in a manner we consider Level B harassment when exposed to underwater anthropogenic noise above received levels of 120 dB re 1 microPascal (µPa) (root mean square (rms)) for continuous ( e.g., vibratory pile-driving) and above 160 dB re 1 µPa (rms) for non-explosive impulsive ( e.g., impact pile driving) or intermittent ( e.g., scientific sonar) sources.
MEDOT's proposed activity includes the use of continuous (vibratory hammer and DTH) and impulsive (impact pile-driving) sources, and therefore the 120 and 160 dB re 1 µPa (rms) thresholds are applicable.
Level A harassment for non-explosive sources -NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). MEDOT's activity includes the use of impulsive (impact pile-driving and DTH) and non-impulsive (vibratory hammer and DTH) sources.
These thresholds are provided in Table 3. The references, analysis, and methodology used in the development of the thresholds are described in NMFS 2018 Technical Guidance, which may be accessed at https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
[top]
| Hearing group | PTS onset acoustic thresholds?* (received level) | Impulsive | Non-impulsive |
|---|---|---|---|
| Low-Frequency (LF) Cetaceans | Cell 1: L pk,flat : 219 dB; L E,LF,24h : 183 dB | Cell 2: L E,LF,24h : 199 dB. | |
| Mid-Frequency (MF) Cetaceans | Cell 3: L pk,flat : 230 dB; L E,MF,24h : 185 dB | Cell 4: L E,MF,24h : 198 dB. | |
| High-Frequency (HF) Cetaceans | Cell 5: L pk,flat : 202 dB; L E,HF,24h : 155 dB | Cell 6: L E,HF,24h : 173 dB. | |
| Phocid Pinnipeds (PW) (Underwater) | Cell 7: L pk,flat : 218 dB; L E,PW,24h : 185 dB | Cell 8: L E,PW,24h : 201 dB. | |
| Otariid Pinnipeds (OW) (Underwater) | Cell 9: L pk,flat : 232 dB; L E,OW,24h : 203 dB | Cell 10: L E,OW,24h : 219 dB. | |
| *?Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered. |
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| Note: Peak sound pressure ( L pk ) has a reference value of 1 µPa, and cumulative sound exposure level ( L E ) has a reference value of 1µPa 2 s. In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript "flat" is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be exceeded in a multitude of ways ( i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be exceeded. | |||
Ensonified Area
Here, we describe operational and environmental parameters of the activity that will feed into identifying the area ensonified above the acoustic thresholds, which include source levels and transmission loss coefficient.
The sound field in the project area is the existing background noise plus additional construction noise from the proposed project. Marine mammals are expected to be affected via sound generated by the primary components of the project ( i.e., impact and vibratory pile driving, and DTH).
In order to calculate distances to the Level A harassment and Level B harassment sound thresholds for the methods and piles being used in this project, NMFS used acoustic monitoring data from other locations to develop source levels for the various pile types, sizes and methods (Table 4).
| Method | Estimated noise levels (dB) | Source |
|---|---|---|
| DTH-24-inch impulsive (Level A) | 154 SELss | Denes et al. (2016). |
| DTH-8-inch impulsive (Level A) | 144 SELss | Reyff (2020). |
| DTH-non-impulsive (Level B) All sizes | 166 dB RMS | Denes et al. (2016). |
| Impact-24-inch | 203 Pk, 177 SEL | Caltrans (2015). |
| Vibratory-24-inch | 165 RMS | Caltrans (2015). |
| Note: SEL = single strike sound exposure level; RMS = root mean square. | ||
Level B Harassment Zones
Transmission loss (TL) is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is:
TL = B * Log10 (R1/R2),
where
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement
The recommended TL coefficient for most nearshore environments is the practical spreading value of 15. This value results in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions, which is the most appropriate assumption for MEDOT's proposed activity in the absence of specific modelling.
MEDOT determined underwater noise would fall below the behavioral effects threshold of 160 dB RMS for impact driving at 1,585 m and the 120 dB rms threshold for vibratory driving at 10,000 m and all diameters of holes created by DTH at 11,660 m (Table 5). It should be noted that based on the bathymetry and geography of the project area, sound will not reach the full distance of the harassment isopleths in all directions (see Application Figures 6-3 and 6-4).
| Method | Piles per day | MF | HF | Phocid | Level B |
|---|---|---|---|---|---|
| DTH-24-inch | 1 | 6 | 199 | 89 | 11,660 |
| 2 | 10 | 315 | 142 | ||
| 3 | 13 | 413 | 186 | ||
| DTH-8-inch | 1 | 2 | 43 | 20 | |
| 2 | 2 | 68 | 31 | ||
| 3 | 3 | 89 | 40 | ||
| Impact-24-inch | 1 | 1 | 35 | 16 | 1,585 |
| 2 | 2 | 56 | 25 | ||
| 3 | 3 | 73 | 33 | ||
| Vibratory-24-inch | 3 | 2 | 25 | 11 | 10,000 |
Level A Harassment Zones
[top] When the NMFS Technical Guidance (2016) was published, in recognition of the fact that ensonified area/volume could be more technically challenging to predict because of the duration component in the new thresholds, we developed a User Spreadsheet that includes tools to help predict a simple isopleth that can be used in conjunction with marine mammal density or occurrence to help predict takes. We note that because of some of the assumptions included in the methods used for these tools, we anticipate that isopleths produced are typically going to be overestimates of some degree, which may result in some degree of overestimate of take by Level A harassment. However, these tools offer the best way to predict appropriate isopleths when more sophisticated 3D modeling methods are not available, and NMFS continues to develop ways to
| Method | Piles per day | Strikes per pile or duration (min) |
|---|---|---|
| DTH-24-inch | 1-3 | 54,000 |
| DTH-8-inch | 1-3 | 54,000 |
| Impact-24-inch | 1-3 | 20 |
| Vibratory-24-inch | 3 | 30 |
Marine Mammal Occurrence and Take Calculation and Estimation
In this section we provide the information about the presence, density, or group dynamics of marine mammals that will inform the take calculations. Here we describe how the information provided above is brought together to produce a quantitative take estimate. The main information used to inform take calculations is the Shaw Institute (2018) monitoring study commissioned for this project and discussed above. Density of animals from that study was calculated for either side of the bridge and was applied to the size of the Level B harassment zones (see Application Section 6.3 for full details). A summary of proposed take is in Table 7.
Atlantic White-Sided Dolphin
Density data for this species in the project vicinity do not exist as no Atlantic white-sided dolphin were seen in the Shaw Institute (2018) study. Atlantic white-sided dolphins do not generally occur in the shallow, inland bays and estuaries of Maine. However, some could occur in rare circumstances. To be precautionary, we propose to authorize take for two groups of 20 animals over the course of the project. Therefore, we propose to authorize 40 Level B harassment takes of Atlantic white-sided dolphins. No takes by Level A harassment are expected or proposed for authorization because we expect MEDOT will effectively shutdown for Atlantic white-sided dolphins at the full extent of the very small Level A harassment zones.
Common Dolphin
Density data for this species in the project vicinity do not exist as no common dolphin were seen in the Shaw Institute (2018) study. Common dolphins do not generally occur in the shallow, inland bays and estuaries of Maine. However, some could occur in rare circumstances. As with Atlantic white-sided dolphins above, to be precautionary, we propose to authorize take for two groups of 20 animals over the course of the project. Therefore, we propose to authorize 40 Level B harassment takes of common dolphins. No takes by Level A harassment are expected or proposed for authorization because we expect MEDOT will effectively shutdown for common dolphins at the full extent of the very small Level A harassment zones.
Harbor Porpoise
The peak month of observation from Shaw Institute (2018) was May when the equivalent of 40 harbor porpoise per day would be observed in the Level B harassment zone for DTH. With 80 days of in-water work for the project we estimate potential Level B harassment take events at 3,200 for harbor porpoise. No takes by Level A harassment are expected or proposed for authorization because we expect MEDOT will effectively shutdown for harbor porpoises at the full extent of the small Level A harassment zones.
Harbor Seal
The peak month of observation from Shaw Institute (2018) was August when the equivalent of 99 seals per day would be observed in the Level B harassment zone for DTH. With 80 days of in-water work for the project we estimate potential Level B harassment zone exposures for harbor seals at 7,920.
Because of the larger size of the Level A harassment zones for 24-inch DTH and the abundance of harbor seals, we propose to authorize 2 of the above assumed 99 takes per day by Level A harassment for the 48 days of possible DTH activity. Thus of the 7,920 assumed harbor seal exposures we propose to authorize 96 Level A harassment takes and 7,824 Level B harassment takes.
Gray Seal
The peak month of observation from Shaw Institute (2018) was July when the equivalent of 4 seals per day would be observed in the Level B harassment zone for DTH. With 80 days of in-water work for the project we estimate potential Level B harassment takes for gray seals at 320. No takes by Level A harassment are expected or proposed for authorization because we expect MEDOT will effectively shutdown for gray seals at the full extent of the small Level A harassment zones.
Harp Seal
Density data for this species in the project vicinity do not exist as no harp seals were seen in the Shaw Institute (2018) study. Most sightings on record in Maine occur during the winter months when transient individuals extend their range south in search of food. To be precautionary, we propose to authorize 1 take per month of harp seals. The project has 80 days of in water work equivalent to 16 5-day work weeks or 4 months. Therefore, we propose to authorize 4 Level B harassment takes of harp seals. No takes by Level A harassment are expected or proposed for authorization because we expect MEDOT will effectively shutdown for harp seals at the full extent of the small Level A harassment zones.
Hooded Seal
[top] Density data for this species in the project vicinity also do not exist as no hooded seals were seen in the Shaw Institute (2018) study. Most sightings on record in Maine occur during the winter months when transient individuals extend their range south in search of food. As with harp seals, above, to be precautionary, we propose to authorize 1 take per month of hooded seals. Therefore, we propose to authorize 4 Level B harassment takes of hooded
| Common name | Scientific name | Stock | Level A | Level B | Percent of stock |
|---|---|---|---|---|---|
| Harbor porpoise | Phocoena phocoena | Gulf Maine/Bay of Fundy | 0 | 3,200 | 3.3 |
| Atlantic white-sided dolphin | Lagenorhynchus acutus | Western North Atlantic | 0 | 40 | <0.1 |
| Common dolphin | Delphinus delphis | Western North Atlantic | 0 | 40 | <0.1 |
| Harbor seal | Phoca vitulina | Western North Atlantic | 96 | 7,824 | 12.8 |
| Gray seal | Halichoerus grypus | Western North Atlantic | 0 | 320 | <0.1 |
| Harp seal | Pagophilus groenlandicus | Western North Atlantic | 0 | 4 | <0.1 |
| Hooded seal | Cystophora cristata | Western North Atlantic | 0 | 4 | NA |
| NA-not available as there is no official stock size estimate. | |||||
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity, and other means of effecting the least practicable impact on the species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stock for taking for certain subsistence uses (latter not applicable for this action). NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting the activity or other means of effecting the least practicable adverse impact upon the affected species or stocks and their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to ensure the least practicable adverse impact on species or stocks and their habitat, as well as subsistence uses where applicable, we carefully consider two primary factors:
(1) The manner in which, and the degree to which, the successful implementation of the measure(s) is expected to reduce impacts to marine mammals, marine mammal species or stocks, and their habitat. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned); and
(2) The practicability of the measures for applicant implementation, which may consider such things as cost, impact on operations, and, in the case of a military readiness activity, personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity.
The following mitigation measures are proposed in the IHA:
• Avoid direct physical interaction with marine mammals during construction activity. If a marine mammal comes within 10 m of such activity, operations must cease and vessels must reduce speed to the minimum level required to maintain steerage and safe working conditions;
• Conduct training between construction supervisors and crews and the marine mammal monitoring team and relevant MEDOT staff prior to the start of all pile driving and DTH activity and when new personnel join the work, so that responsibilities, communication procedures, monitoring protocols, and operational procedures are clearly understood;
• Pile driving activity must be halted upon observation of either a species for which incidental take is not authorized or a species for which incidental take has been authorized but the authorized number of takes has been met, entering or within the harassment zone;
• MEDOT will establish and implement the shutdown zones indicated in Table 8. The purpose of a shutdown zone is generally to define an area within which shutdown of the activity would occur upon sighting of a marine mammal (or in anticipation of an animal entering the defined area). Shutdown zones typically vary based on the activity type and marine mammal hearing group. To simplify implementation of shutdown zones MEDOT has proposed to implement shutdown zones for two groups of marine mammals, cetaceans and pinnipeds, with the shutdown zone in each group being the largest of the shutdown zones for any of the hearing groups contained within that group. MEDOT has also voluntarily proposed to increase shutdown sizes above those we would typically require in order to be precautionary and protective to marine mammals. They have proposed to round-up shutdown zone sizes to the next highest 50 m from the distances in Table 5. For comparison purposes, Table 8 shows both the minimum shutdown zones we would normally require and the shutdown zones MEDOT proposes to implement. NMFS proposes to include the latter in the requested IHA;
• Employ Protected Species Observers (PSOs) and establish monitoring locations as described in the Marine Mammal Monitoring Plan and Section 5 of the IHA. MEDOT must monitor the project area to the maximum extent possible based on the required number of PSOs, required monitoring locations, and environmental conditions. For all DTH, pile driving and removal at least one PSO must be used. The PSO will be stationed as close to the activity as possible;
• The placement of the PSOs during all pile driving and removal and DTH activities will ensure that the entire shutdown zone is visible during pile installation. Should environmental conditions deteriorate such that marine mammals within the entire shutdown zone will not be visible ( e.g., fog, heavy rain), pile driving and removal must be delayed until the PSO is confident marine mammals within the shutdown zone could be detected;
[top] • Monitoring must take place from 30 minutes prior to initiation of pile driving activity through 30 minutes post-completion of pile driving activity. Pre-start clearance monitoring must be conducted during periods of visibility sufficient for the lead PSO to determine the shutdown zones clear of marine mammals. Pile driving may commence
• If pile driving is delayed or halted due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zone or 15 minutes have passed without re-detection of the animal; and
• MEDOT must use soft start techniques when impact pile driving. Soft start requires contractors to provide an initial set of three strikes at reduced energy, followed by a 30-second waiting period, then two subsequent reduced-energy strike sets. A soft start must be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer;
| Method | Piles per day | MF | HF | Phocid | Cetacean | Pinniped |
|---|---|---|---|---|---|---|
| DTH-24-inch | 1 | 10 | 200 | 90 | 200 | 100 |
| 2 | 10 | 320 | 150 | 350 | 200 | |
| 3 | 20 | 420 | 190 | 450 | 200 | |
| DTH-8-inch | 1 | 10 | 50 | 20 | 100 | 50 |
| 2 | 10 | 70 | 40 | 100 | 50 | |
| 3 | 10 | 90 | 40 | 100 | 50 | |
| Impact-24-inch | 1 | 10 | 40 | 20 | 50 | 50 |
| 2 | 10 | 60 | 30 | 100 | 50 | |
| 3 | 10 | 80 | 40 | 100 | 50 | |
| Vibratory-24-inch | 3 | 10 | 30 | 20 | 50 | 50 |
| Note: First three columns are what NMFS would consider appropriate in this circumstance, and the last two are what the applicant has proposed and what NMFS proposes to include in the IHA. | ||||||
Based on our evaluation of the applicant's proposed measures, as well as other measures considered by NMFS, NMFS has preliminarily determined that the proposed mitigation measures provide the means effecting the least practicable impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of the MMPA states that NMFS must set forth requirements pertaining to the monitoring and reporting of such taking. The MMPA implementing regulations at 50 CFR 216.104 (a)(13) indicate that requests for authorizations must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that are expected to be present in the proposed action area. Effective reporting is critical both to compliance as well as ensuring that the most value is obtained from the required monitoring.
Monitoring and reporting requirements prescribed by NMFS should contribute to improved understanding of one or more of the following:
• Occurrence of marine mammal species or stocks in the area in which take is anticipated ( e.g., presence, abundance, distribution, density);
• Nature, scope, or context of likely marine mammal exposure to potential stressors/impacts (individual or cumulative, acute or chronic), through better understanding of: (1) Action or environment ( e.g., source characterization, propagation, ambient noise); (2) affected species ( e.g., life history, dive patterns); (3) co-occurrence of marine mammal species with the action; or (4) biological or behavioral context of exposure ( e.g., age, calving or feeding areas);
• Individual marine mammal responses (behavioral or physiological) to acoustic stressors (acute, chronic, or cumulative), other stressors, or cumulative impacts from multiple stressors;
• How anticipated responses to stressors impact either: (1) Long-term fitness and survival of individual marine mammals; or (2) populations, species, or stocks;
• Effects on marine mammal habitat ( e.g., marine mammal prey species, acoustic habitat, or other important physical components of marine mammal habitat); and
• Mitigation and monitoring effectiveness.
Visual Monitoring
• Monitoring must be conducted by qualified, NMFS-approved PSOs, in accordance with the following: PSOs must be independent ( i.e., not construction personnel) and have no other assigned tasks during monitoring periods. At least one PSO must have prior experience performing the duties of a PSO during construction activity pursuant to a NMFS-issued incidental take authorization. Other PSOs may substitute other relevant experience, education (degree in biological science or related field), or training. PSOs must be approved by NMFS prior to beginning any activity subject to this IHA;
• PSOs must record all observations of marine mammals as described in the Section 5 of the IHA and the Marine Mammal Monitoring Plan, regardless of distance from the pile being driven or DTH activity. PSOs shall document any behavioral reactions in concert with distance from piles being driven or removed;
PSOs must have the following additional qualifications:
• Ability to conduct field observations and collect data according to assigned protocols;
• Experience or training in the field identification of marine mammals, including the identification of behaviors;
• Sufficient training, orientation, or experience with the construction operation to provide for personal safety during observations;
• Writing skills sufficient to prepare a report of observations including but not limited to the number and species of marine mammals observed; dates and times when in-water construction activities were conducted; dates, times, and reason for implementation of mitigation (or why mitigation was not implemented when required); and marine mammal behavior; and
[top] • Ability to communicate orally, by radio or in person, with project
• MEDOT must establish the following monitoring locations. For all pile driving and DTH activities, a minimum of one PSO must be assigned to the active pile driving or DTH location to monitor the shutdown zones and as much of the Level A and Level B harassment zones as possible. When a vibratory hammer or DTH is used a second PSO must be located in the Level B harassment zone at one of two shoreline stations east of the bridge (see map in application Figure 13-1).
Reporting
A draft marine mammal monitoring report will be submitted to NMFS within 90 days after the completion of pile driving and removal activities, or 60 days prior to a requested date of issuance of any future IHAs for projects at the same location, whichever comes first. The report will include an overall description of work completed, a narrative regarding marine mammal sightings, and associated PSO data sheets. Specifically, the report must include:
• Dates and times (begin and end) of all marine mammal monitoring;
• Construction activities occurring during each daily observation period, including the number and type of piles driven or removed and by what method ( i.e., impact or cutting) and the total equipment duration for cutting for each pile or total number of strikes for each pile (impact driving);
• PSO locations during marine mammal monitoring;
• Environmental conditions during monitoring periods (at beginning and end of PSO shift and whenever conditions change significantly), including Beaufort sea state and any other relevant weather conditions including cloud cover, fog, sun glare, and overall visibility to the horizon, and estimated observable distance;
• Upon observation of a marine mammal, the following information: Name of PSO who sighted the animal(s) and PSO location and activity at time of sighting; Time of sighting; Identification of the animal(s) ( e.g., genus/species, lowest possible taxonomic level, or unidentified), PSO confidence in identification, and the composition of the group if there is a mix of species; Distance and bearing of each marine mammal observed relative to the pile being driven for each sighting (if pile driving was occurring at time of sighting); Estimated number of animals (min/max/best estimate); Estimated number of animals by cohort (adults, juveniles, neonates, group composition, etc.); Animal's closest point of approach and estimated time spent within the harassment zone; Description of any marine mammal behavioral observations ( e.g., observed behaviors such as feeding or traveling), including an assessment of behavioral responses thought to have resulted from the activity ( e.g., no response or changes in behavioral state such as ceasing feeding, changing direction, flushing, or breaching);
• Number of marine mammals detected within the harassment zones, by species; and
• Detailed information about any implementation of any mitigation triggered ( e.g., shutdowns and delays), a description of specific actions that ensued, and resulting changes in behavior of the animal(s), if any.
If no comments are received from NMFS within 30 days, the draft final report will constitute the final report. If comments are received, a final report addressing NMFS comments must be submitted within 30 days after receipt of comments.
Reporting Injured or Dead Marine Mammals
In the event that personnel involved in the construction activities discover an injured or dead marine mammal, the IHA-holder must immediately cease the specified activities and report the incident to the Office of Protected Resources (OPR) ( PR.ITP.MonitoringReports@noaa.gov ), NMFS and to Greater Atlantic Regional Stranding Coordinator as soon as feasible. If the death or injury was clearly caused by the specified activity, MEDOT must immediately cease the specified activities until NMFS is able to review the circumstances of the incident and determine what, if any, additional measures are appropriate to ensure compliance with the terms of the IHA. The IHA-holder must not resume their activities until notified by NMFS. The report must include the following information:
• Time, date, and location (latitude/longitude) of the first discovery (and updated location information if known and applicable);
• Species identification (if known) or description of the animal(s) involved;
• Condition of the animal(s) (including carcass condition if the animal is dead);
• Observed behaviors of the animal(s), if alive;
• If available, photographs or video footage of the animal(s); and
• General circumstances under which the animal was discovered.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival (50 CFR 216.103). A negligible impact finding is based on the lack of likely adverse effects on annual rates of recruitment or survival ( i.e., population-level effects). An estimate of the number of takes alone is not enough information on which to base an impact determination. In addition to considering estimates of the number of marine mammals that might be "taken" through harassment, NMFS considers other factors, such as the likely nature of any responses ( e.g., intensity, duration), the context of any responses ( e.g., critical reproductive time or location, migration), as well as effects on habitat, and the likely effectiveness of the mitigation. We also assess the number, intensity, and context of estimated takes by evaluating this information relative to population status. Consistent with the 1989 preamble for NMFS's implementing regulations (54 FR 40338; September 29, 1989), the impacts from other past and ongoing anthropogenic activities are incorporated into this analysis via their impacts on the environmental baseline ( e.g., as reflected in the regulatory status of the species, population size and growth rate where known, ongoing sources of human-caused mortality, or ambient noise levels).
Pile driving and removal and DTH activities have the potential to disturb or displace marine mammals. Specifically, the project activities may result in take, in the form of Level B harassment from underwater sounds generated from pile driving and removal and DTH for all species and a small amount of Level A harassment take for harbor seals. Potential takes could occur if individuals are present in the ensonified zone when these activities are underway.
To avoid repetition, the discussion of our analyses applies to all the species listed in Table 7, given that the anticipated effects of this activity on these different marine mammal stocks are expected to be similar. There is little information about the nature or severity of the impacts, or the size, status, or structure of any of these species or stocks that would lead to a different analysis for this activity.
[top] The takes from Level A and Level B harassment would be due to potential
Many of the Level A harassment zones identified in Table 7 are based upon an animal exposed to pile driving or DTH multiple piles per day. Considering the short duration to impact drive or DTH each pile and breaks between pile installations (to reset equipment and move pile into place), this means an animal would have to remain within the area estimated to be ensonified above the Level A harassment threshold for multiple hours. This is highly unlikely given marine mammal movement throughout the area. If an animal was exposed to accumulated sound energy, the resulting PTS would likely be small ( e.g., PTS onset) at lower frequencies where pile driving energy is concentrated, and unlikely to result in impacts to individual fitness, reproduction, or survival.
The nature of the pile driving project precludes the likelihood of serious injury or mortality. For all species and stocks, take would occur within a limited, confined area (adjacent to the Falls Bridge) of the stock's range. Level A and Level B harassment will be reduced to the level of least practicable adverse impact through use of mitigation measures described herein. Further the amount of take proposed to be authorized is small when compared to stock abundance.
Behavioral responses of marine mammals to pile driving at the project site, if any, are expected to be mild and temporary. Marine mammals within the Level B harassment zone may not show any visual cues they are disturbed by activities (as noted during modification to the Kodiak Ferry Dock) or could become alert, avoid the area, leave the area, or display other mild responses that are not observable such as changes in vocalization patterns. Given the short duration of noise-generating activities per day, any harassment would be temporary. There are no other areas or times of known biological importance for any of the affected species.
In addition, it is unlikely that minor noise effects in a small, localized area of habitat would have any effect on the stocks' ability to recover. In combination, we believe that these factors, as well as the available body of evidence from other similar activities, demonstrate that the potential effects of the specified activities will have only minor, short-term effects on individuals. The specified activities are not expected to impact rates of recruitment or survival and will therefore not result in population-level impacts.
In summary and as described above, the following factors primarily support our preliminary determination that the impacts resulting from this activity are not expected to adversely affect the species or stock through effects on annual rates of recruitment or survival:
• No mortality is anticipated or authorized;
• Authorized Level A harassment of harbor seals would be very small amounts and of low degree;
• No important habitat areas have been identified within the project area;
• For all species, the project is a very small and peripheral part of their range;
• MEDOT would implement mitigation measures such as soft-starts, and shut downs.
Based on the analysis contained herein of the likely effects of the specified activity on marine mammals and their habitat, and taking into consideration the implementation of the proposed monitoring and mitigation measures, NMFS preliminarily finds that the total marine mammal take from the proposed activity will have a negligible impact on all affected marine mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be authorized under section 101(a)(5)(D) of the MMPA for specified activities other than military readiness activities. The MMPA does not define small numbers and so, in practice, where estimated numbers are available, NMFS compares the number of individuals taken to the most appropriate estimation of abundance of the relevant species or stock in our determination of whether an authorization is limited to small numbers of marine mammals. When the predicted number of individuals to be taken is fewer than one third of the species or stock abundance, the take is considered to be of small numbers. Additionally, other qualitative factors may be considered in the analysis, such as the temporal or spatial scale of the activities.
The amount of take NMFS proposes to authorize is below one third of the estimated stock abundance for all species and stocks (in fact, take of individuals is less than 10 percent of the abundance of the affected stocks except for harbor seals where take is 12.8 percent, see Table 7). This is likely a conservative estimate because they assume all takes are of different individual animals which is likely not the case. Some individuals may return multiple times in a day, but PSOs would count them as separate takes if they cannot be individually identified.
In summary and as described above, the following factors primarily support our preliminary determination regarding the incidental take of small numbers of a species or stock:
• The take of marine mammal stocks authorized for take comprises less than 10 percent of any stock abundance (with the exception of harbor seals); and
• Many of the takes would be repeats of the same animal and it is likely that a number of individual animals could be taken 10 or more times.
Based on the analysis contained herein of the proposed activity (including the proposed mitigation and monitoring measures) and the anticipated take of marine mammals, NMFS preliminarily finds that small numbers of marine mammals will be taken relative to the population size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine mammal stocks or species implicated by this action. Therefore, NMFS has determined that the total taking of affected species or stocks would not have an unmitigable adverse impact on the availability of such species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the ESA (16 U.S.C. 1531 et seq. ) requires that each Federal agency insure that any action it authorizes, funds, or carries out is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destruction or adverse modification of designated critical habitat. To ensure ESA compliance for the issuance of IHAs, NMFS consults internally whenever we propose to authorize take for endangered or threatened species.
No incidental take of ESA-listed species is proposed for authorization or expected to result from this activity. Therefore, NMFS has determined that formal consultation under section 7 of the ESA is not required for this action.
Proposed Authorization
[top] As a result of these preliminary determinations, NMFS proposes to issue an IHA to the MEDOT to conduct the Falls Bridge Replacement Project in
Request for Public Comments
We request comment on our analyses, the proposed authorization, and any other aspect of this notice of proposed IHA for the proposed Falls Bridge Replacement Project. We also request at this time comment on the potential renewal of this proposed IHA as described in the paragraph below. Please include with your comments any supporting data or literature citations to help inform decisions on the request for this IHA or a subsequent Renewal IHA.
On a case-by-case basis, NMFS may issue a one-time 1 year Renewal IHA following notice to the public providing an additional 15 days for public comments when (1) up to another year of identical, or nearly identical, activities as described in the Description of Proposed Activity section of this notice is planned or (2) the activities as described in the Description of Proposed Activity section of this notice would not be completed by the time the IHA expires and a Renewal would allow for completion of the activities beyond that described in the Dates and Duration section of this notice, provided all of the following conditions are met:
• A request for renewal is received no later than 60 days prior to the needed Renewal IHA effective date (recognizing that Renewal IHA expiration date cannot extend beyond one year from expiration of the initial IHA);
• The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the requested Renewal IHA are identical to the activities analyzed under the initial IHA, are a subset of the activities, or include changes so minor ( e.g., reduction in pile size) that the changes do not affect the previous analyses, mitigation and monitoring requirements, or take estimates (with the exception of reducing the type or amount of take); and
(2) A preliminary monitoring report showing the results of the required monitoring to date and an explanation showing that the monitoring results do not indicate impacts of a scale or nature not previously analyzed or authorized; and
• Upon review of the request for Renewal, the status of the affected species or stocks, and any other pertinent information, NMFS determines that there are no more than minor changes in the activities, the mitigation and monitoring measures will remain the same and appropriate, and the findings in the initial IHA remain valid.
Dated: November 1, 2021.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries Service.
[FR Doc. 2021-24164 Filed 11-4-21; 8:45 am]
BILLING CODE 3510-22-P