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Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay and the Atlantic Ocean
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Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay and the Atlantic Ocean
A Notice by
the
National Oceanic and Atmospheric Administration
on
09/23/2025
Published Document: 2025-18424 (90 FR 45730)
This document has been published in the
Federal Register
. Use the PDF linked in the document sidebar for the official electronic format.
Published Document: 2025-18424 (90 FR 45730)
Document Details
Published Content - Document Details
Agencies
Department of Commerce
National Oceanic and Atmospheric Administration
Agency/Docket Number
RTID 0648-XF146
Document Citation
90 FR 45730
Document Number
2025-18424
Document Type
Notice
Pages
45730-45750
(21 pages)
Publication Date
09/23/2025
Published Content - Document Details
PDF
Official Content
View printed version (PDF)
Official Content
Document Details
Published Content - Document Details
Agencies
Department of Commerce
National Oceanic and Atmospheric Administration
Agency/Docket Number
RTID 0648-XF146
Document Citation
90 FR 45730
Document Number
2025-18424
Document Type
Notice
Pages
45730-45750
(21 pages)
Publication Date
09/23/2025
Published Content - Document Details
Document Dates
Published Content - Document Dates
Dates Text
This authorization is effective for 1 year from the date of notification by the IHA-holder, not to exceed 1 year from the date of issuance (September 19, 2025).
Published Content - Document Dates
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AGENCY:
ACTION:
SUMMARY:
DATES:
ADDRESSES:
FOR FURTHER INFORMATION CONTACT:
SUPPLEMENTARY INFORMATION:
Background
Summary of Request
Description of the Specified Activity
Comments and Responses
Changes From the Proposed IHA to the Final IHA
Description of Marine Mammals in the Area of Specified Activities
Marine Mammal Hearing
Potential Effects of Specified Activities on Marine Mammals and Their Habitat
Estimated Take of Marine Mammals
Acoustic Criteria
Ensonified Area
Marine Mammal Occurrence
Take Estimation
Mitigation
Vessel Strike Avoidance Measures
Shutdown Zones
PSOs
Monitoring for Level A and Level B Harassment
Pre-and-Post-Activity Monitoring
Soft Start
Monitoring and Reporting
Visual Monitoring
North Atlantic Right Whale and Other Marine Mammal Awareness
Reporting
North Atlantic Right Whale Reporting
Negligible Impact Analysis and Determination
Small Numbers
Unmitigable Adverse Impact Analysis and Determination
Endangered Species Act
National Environmental Policy Act
Authorization
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Department of Commerce
National Oceanic and Atmospheric Administration
[RTID 0648-XF146]
AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION:
Notice; issuance of an incidental harassment authorization.
SUMMARY:
Notification is hereby given that NMFS has issued an incidental harassment authorization (IHA) to Transcontinental Gas Pipe Line Company, LLC (Transco), a subsidiary of Williams Partners L.P., to incidentally harass marine mammals during construction activities associated with the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay, and the Atlantic Ocean.
DATES:
This authorization is effective for 1 year from the date of notification by the IHA-holder, not to exceed 1 year from the date of issuance (September 19, 2025).
ADDRESSES:
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:
printed page 45731)
take-authorizations-construction-activities
In case of problems accessing these documents, please call the contact listed below.
FOR FURTHER INFORMATION CONTACT:
Kate Fleming, Office of Protected Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the “take” of marine mammals, with certain exceptions. Section 101(a)(5)(A) and (D) of the MMPA (
16 U.S.C. 1361
et seq.
) directs the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are proposed or, if the taking is limited to harassment, a notice of a proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (collectively referred to as “mitigation”); and requirements pertaining to the monitoring and reporting of the takings. The definitions of all applicable MMPA statutory terms used above are included in the relevant sections below and can be found in section 3 of the MMPA (
16 U.S.C. 1362
) and NMFS regulations at
50 CFR 216.103
Summary of Request
On May 30, 2025, NMFS received a request from Transco for an IHA to take marine mammals incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay and the Atlantic Ocean (in the New York Bight). During NMFS' application review, Transco indicated that two hammers at the same location may operate at the same time and provided scenarios for simultaneous pile driving on July 11, 2025, which necessitated additional analysis. Following NMFS' review of the application and subsequent discussions between NMFS and Transco, the application was deemed adequate and complete on July 29, 2025. Transco's initial request was for authorization of take of 14 species of marine mammals by Level B harassment and, for a subset of 4 of these species, Level A harassment. Following additional analysis, NMFS proposed to authorize take of 15 species of marine mammals by Level B harassment and, for a subset of 7 of these species, Level A harassment (
90 FR 38104
, August 7, 2025). NMFS has authorized this take as proposed. Neither Transco nor NMFS expect serious injury or mortality to result from this activity and, therefore, an IHA is appropriate.
NMFS previously issued an IHA to Transco for the same project (
85 FR 15125
, March 17, 2020) as updated in the 2025 application. No work was conducted under the 2020 IHA. NMFS also previously issued a separate IHA to Transco for its Lower New York Bay Lateral Maintenance (LNYBL) that occurred in the same region (
89 FR 20170
, March 21, 2024). Transco conducted all required monitoring and reporting under the 2024 IHA, and information regarding Transco's monitoring results may be found in the Potential Effects of the Specified Activity on Marine Mammals and their Habitat section of the proposed IHA (
90 FR 38104
, August 7, 2025).
Description of the Specified Activity
Transco plans to expand its existing interstate natural gas transmission system in Pennsylvania and New Jersey and its existing offshore natural gas transmission system in New Jersey and New York waters. The offshore pipeline facilities would include the installation of the Raritan Bay Loop, which would be located primarily in Raritan Bay, as well as parts of the Lower New York Bay and the Atlantic Ocean.
Construction of the Raritan Bay Loop pipeline would require vibratory and impact installation and vibratory removal of 163 temporary piles, ranging in size from 10 to 60-inches (in) (0.3 to 1.5 meters (m)) in diameter, which may result in the incidental take of marine mammals.
A detailed description of the planned construction activities is provided in the
Federal Register
notice for the proposed IHA (
90 FR 38104
, August 7, 2025). Since that time, no changes have been made to the planned activities. Therefore, a detailed description is not provided here. Please refer to that
Federal Register
notice for the description of the specific activity.
Comments and Responses
NMFS published a notice of its proposal to issue an IHA to Transco in the
Federal Register
on August 7, 2025 (
90 FR 38104
). That notice described, in detail, Transco's specified activities, the marine mammal species that may be affected by the activities, and the anticipated effects on marine mammals. In that notice, we requested public input on the request for authorization described therein, our analyses, the proposed authorization, and any other aspect of the notice of the proposed IHA, and requested that interested persons submit relevant information, suggestions, and comments.
During the 30-day public comment period, NMFS received a total of five substantive comment letters. Letters were received from one state agency (New York State Department of Environmental Conservation), three environmental non-governmental organizations (Clean Ocean Action, New Yorkers for Clean Power, Protect Our Coast New Jersey), and from the “WhoPoo App” entity. Summaries of all relevant, substantive comments and NMFS' responses to these comments are provided below. We have not responded to comments that failed to raise a significant point for us to consider (
e.g.,
comments that are out of scope of the proposed IHA; mitigation, monitoring, or reporting measures already included in the proposed IHA). Furthermore, if a comment received was unclear, NMFS does not include it here as it could not determine whether it raised a significant point for NMFS to consider. The comments are available online at:
Please see the comment submissions for full details regarding the recommendations and supporting rationale.
Comment 1:
Commenters expressed concern regarding NMFS' proposed application of a National Environmental Policy Act (NEPA) Categorical Exclusion (CatEx). Commenters stated that use of the CatEx is inappropriate given what one commentator characterizes as “the uncertainty and uniqueness of the impacts” related to contaminants that the commenter asserts would be released by the project or what a different commenter describes as the “potential for serious acoustic disturbance to sensitive marine mammals,” and recommended that further NEPA analysis be conducted.
Response:
In determining whether a CatEx is appropriately applied for a given Incidental Take Authorization
printed page 45732)
(ITA), NMFS considers the applicant's specified activity, in this case, in-water construction (pile driving), and the potential extent and magnitude of the effects of NMFS' action (
i.e.,
the authorized “takes” of marine mammals and prescribed mitigation, monitoring and reporting requirements) along with the extraordinary circumstances listed in the Companion Manual for NOAA Administrative Order 216-6A. The evaluation of whether extraordinary circumstances (if present) have the potential for significant environmental effects is limited to the decision NMFS is responsible for, which is issuance of an ITA (NMFS' action). NMFS has prepared numerous Environmental Assessments (EAs) analyzing the environmental impacts of authorizing take of marine mammals incidental to construction activities such as these, which resulted in Findings of No Significant Impact. NMFS has performed the necessary analysis and confirmed that there are no extraordinary circumstances present that would make use of the CatEx inappropriate for NMFS' action of issuing an ITA for the construction activities associated with Transco's Northeast Supply Enhancement project. The commenters do not provide adequate support for the apparent contention that there may be extraordinary circumstances associated with NMFS' action of issuing the IHA.
Comment 2:
One commenter stated that “significant resuspension of [. . .] toxin-laced sediments” would occur as a result of the project, specifically dredging, and suggested that resulting impacts on marine mammals were not adequately addressed by NMFS. As discussed in response to Comment 1, the commenter additionally suggested that these potential impacts presented extraordinary circumstances that would make NMFS' proposed application of a CatEx inappropriate.
Response:
NMFS clarifies that our proposed action—the issuance of the IHA authorizing incidental take of marine mammals from the specified activities (
i.e.,
pile driving)—analyzed the impacts of the specified activities on marine mammals, including impacts to habitat and potential prey species. Transco did not request and NMFS is not authorizing incidental take of marine mammals from Transco's dredging activities. As we discussed in the proposed
Federal Register
notice (
90 FR 38104
, August 7, 2025), there is no information suggesting more than temporary, localized impacts to water quality and temporary impacts to marine mammal prey from pile driving activities and, in fact, the commenter refers to what it states are expected impacts as “temporary loss of habitat and foraging areas.”
The project area has not been identified as particularly important foraging habitat for marine mammals, except for humpback whales, which may use it as supplementary feeding habitat. In addition, Estabrook
et al.
(2025) noted that humpback whale calls were more frequently detected near New York Harbor between November and March, and at sites near the shelf edge, away from the project area, between July and September when most of the project activities are planned. NMFS' review of the available information does not indicate that the expected temporary effects could be significant enough to impact marine mammal prey to the extent that marine mammal fitness would be affected. As stated in the proposed
Federal Register
notice (
90 FR 38104
, August 7, 2025), our review of the available information and the specific nature of the activities considered herein suggest that the specified activities are not likely to have more than temporary adverse effects on any prey habitat or populations of prey species. Further, any impacts to prey species are not expected to result in significant or long-term consequences for individual marine mammals, or to contribute to adverse impacts on their populations. The commenter does not provide evidence to the contrary. We have appropriately considered effects to marine mammal habitat and, as discussed in response to comment 1, the concerns raised by the commenter do not present extraordinary circumstances that would invalidate NMFS use of the CatEx in this circumstance.
Comment 3:
Commenters expressed concern regarding the effects of incidental takes on certain species of marine mammals based on what the commenters describe as other threats these species face in the region, and state that NMFS should deny the requested authorization on this basis.
Response:
Along varying ranges of the Atlantic coast, there have been ongoing Unusual Mortality Events (UMEs) for North Atlantic right whales, humpback whales, and minke whales, which includes animals stranded since 2017, 2016, and 2017, respectively. We provide further information on these UMEs in the Description of Marine Mammals in the Area of Specified Activities section of the proposed IHA (August 7, 2025,
90 FR 38104
).Ongoing UMEs for humpback and minke whales do not provide meaningful cause for concern at the population level for these marine mammal stocks. Far from indicating that these species are in crisis, as is suggested by commenters stating that no takes should be authorized for these species, these species are healthy, with estimated population abundance exceeding 10,000 and 20,000 animals, respectively. For North Atlantic right whales, while we agree that the species faces significant threats, primarily from vessel strike and entanglement in fishing gear, we do not agree with the suggestion that the population cannot sustain 12 incidents of Level B harassment, which are likely to be relatively low-level, temporary behavioral reactions with no lasting significance for the impacted individuals.
As described in this notice of final IHA, NMFS finds that small numbers of marine mammals may be taken relative to the population size of the affected species or stocks and that the incidental take of marine mammal from Transco's specified activities will have a negligible impact on all affected marine mammal species or stocks.
Comment 4:
A commenter states that modeling and past monitoring data are not adequate to assess real-time presence of at-risk species, and do not consider seasonal fluctuations in population density, and as such, asserts that the precautionary principle demands stricter mitigation or deferral is necessary to ensure effective protections.
Response:
NMFS is required to issue the requested ITA if the necessary findings are made based on the best scientific information available (
16 U.S.C. 1371(a)(5)(A)(i)
). In this case, NMFS considered the best available marine mammal density data, published and peer reviewed scientific literature, on-the-water reports from other nearby projects and monitoring from past MMPA actions in the area. Seasonal fluctuations in population density have been accounted for in the density analysis, as the mean density across the total project period was compared to the mean density across the year and the largest value was the selected input calculating take estimates. The commenter did not provide additional scientific information regarding marine mammal presence for NMFS to consider. The commenter did not provide evidence to support the claim that the mitigation measures are not sufficient to affect the least practicable impact on the species or stock and its habitat and did not recommend additional mitigation measures for NMFS to consider.
Comment 5:
A commenter suggests that the required length of time to conduct re-detection monitoring should be extended before work recommences,
printed page 45733)
referencing. Smith
et al.,
2022, which reports humpback whales lunge-feeding in shallow waters including in the project area.
Response:
Given the evidence presented, in which humpback whales have been documented lunge feeding in shallow habitats, including in the project area, NMFS agrees that an increase in re-detection monitoring to 30 minutes following a shutdown is reasonable for low frequency cetaceans and has revised relevant mitigation measures.
Comment 6:
Commenters suggest that the proposed mitigation requirements are inadequate, including a statement that the proposed requirements do not “establish adequate safeguard thresholds or clear criteria for halting operations.” A commenter states that Transco must be required to follow the same mitigation and monitoring requirements that have been included in certain ITAs (
e.g.,
offshore wind project construction), while another commenter specifically recommends that NMFS require use of passive acoustic monitoring (PAM), and state that NMFS should restrict pile driving to within seasonal windows when marine mammals are less abundant and should “develop clear, enforceable, operational triggers requiring immediate shutdown upon detection of protected species”. The commenter also claims the IHA lacks transparent adaptive management measures.
Response:
The commenters have not provided evidence to support their conclusion that the proposed mitigation measures are not sufficient to affect the least practicable adverse impact on species or stocks and their habitat. NMFS first emphasizes that mitigation measures are specified activity specific and designed to mitigate specific effects. Thus, mitigation measures included in one ITA may not be appropriate for another ITA (
e.g.,
sound related mitigation measures for pile driving of offshore wind turbine
foundations
versus measures for pile driving temporary piles with a maximum diameter of 1.5 m). Implementation of noise attenuation devices and sound field verification would be costly and logistically challenging given the nature of the activity, in which Transco plans to vibratory install 163 piles along a string at 8 locations in 43 days and removing the same piles in 26 days, and impact installing 34 piles along a string at 3 locations separated by >20 km in some instances. Such measures would likely increase project costs and create delays. NMFS is not requiring a dedicated PSO vessel because the IHA requires PSOs to monitor from each pile driving location and the shutdown zones are reliably observable from this location. In addition to complying with existing vessel speed restrictions for North Atlantic right whales, NMFS highlights that Transco also intends to comply with voluntary programs NMFS uses to notify vessel operators to slow down to avoid right whales. Transco has agreed to adhere to rules for DMAs if they are designated by NMFS in the project area during the project, which could be established any time of year; as such, should a DMA be established outside of the SMA, Transco has indicated they will voluntarily comply. NMFS does not find it reasonable to require that Transco adhere to vessel speed restrictions outside these programs designed to protect right whales, given the relatively low occurrence of this species, as well as other low-frequency cetaceans, in the project area.
While we acknowledge that use of PAM provides utility for detection of vocalizing marine mammals that may not be detected by visual observers, development and implementation of such systems carry meaningful operational costs. Use of PAM systems as a component of an overall monitoring approach has been included as a requirement in certain incidental take authorizations with greater expected potential for impacts to marine mammals,
e.g.,
multi-year offshore pile driving associated with wind energy development. However, for activities with lower expected potential for impacts to marine mammals, including more typical inshore coastal construction actions of shorter duration similar to what is planned by Transco, use of PAM is not a typical requirement due to the costs of operation relative to the expected benefits of the addition of what is expected to be a relatively limited incremental addition in terms of monitoring capability in this context,
e.g.,
inshore, daylight only, and with relatively small harassment zones for impact pile driving. Therefore, NMFS is not requiring Transco to implement PAM.
The commenters do not provide a recommended time of year or suggest which species should be prioritized in establishing seasonal restrictions. Migrating North Atlantic right whales are most likely to be in the project area between November and April while other species that may reasonably be considered as priorities for protection are more likely to occur in the spring and summer months. Additionally, harbor porpoises are expected to occur in highest densities in the spring and fall while pinnipeds are expected to occur in the winter and spring only. Transco intends to complete pile driving activities June through November when North Atlantic right whale and pinniped occurrences are less likely to be in the project area. NMFS disagrees that a time of year restriction is necessary to affect the least practicable adverse impact on marine mammals.
It is unclear what the commenter means by developing clear, enforceable operational triggers requiring immediate shutdown upon detection of protected species. The establishment and implementation of shutdown zones are described in the shutdown zone and pre and post activity monitoring headings of the Mitigation sections in the proposed
Federal Register
notice (
90 FR 38104
, August 7, 2025) and herein. Regarding the commenter's concern about a lack of detail regarding shutdown implementation, NMFS has further explained that process here. In the event that pile driving is underway when a marine mammal is observed entering or within the shutdown zone, pile driving must be halted. In the event that pile driving is not currently underway (
e.g.,
at the beginning of a work day, when a pile is being positioned for driving,
etc.
) when a marine mammal is observed entering or within the shutdown zone, pile driving must be delayed (
i.e.,
not begin). For both scenarios, pile driving cannot begin (in the case of a delay) or resume (in the case of a halt) until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zone or the required amount of time has passed without re-detection of the animal. NMFS expects that in coastal environments where the water is relatively shallow and therefore, most marine mammal dives are generally shorter, 15 minutes is sufficient to conclude that most animals are no longer within the shutdown zone. In the case of large whales, NMFS has extended the re-detection monitoring period to 30 minutes, to account for humpback whale lunge-feeding behavior reported in the project area (Smith
et al.,
2022). The protocol for pausing activities based on real-time evidence of injury or death of a marine mammal, in which it is apparent that the death or injury is caused by the specified activity, is described in the reporting section of the IHA.
Adaptive management is not typically included in IHAs because of their short effective period (contrast incidental take regulations and associated letters of authorizations that may be effective for up to five years).
Comment 8:
NYDEC recommends revisions to reporting requirements to
printed page 45734)
ensure that any sightings of cetaceans be shared with local stranding network partners as soon as feasible. NYDEC points to the chance of stranding(s) and/or out of habitat movement subsequent to project activities, to suggest that local awareness (
i.e.,
the states of New York and New Jersey and the federally permitted stranding response groups in each state) of (potentially) at-risk animals should be prioritized via near real-time communications. Specifically NYDEC requests that: (1) as soon as feasible and by the end of the day, report North Atlantic right whale sightings to NMFS at 866-755-6622 and, (2) as soon as feasible and by the end of the day, report all cetacean sightings to the above referenced NMFS hotline and the local state stranding hotlines.
Response:
NMFS agrees that it is reasonable for Transco to report North Atlantic right whale sightings to the NOAA/GARFO hotline and has added a requirement to the IHA to ensure that this is reported immediately and no longer than 24 hours after the sighting rather than the end of the day, as well as the RWSAS or through the Whale Alert App.
NMFS also notes that Transco is required to report discoveries of injured or dead marine mammals to the Office of Protected Resources (OPR), and to the Northeast Marine Mammal and Sea Turtle Entanglement Hotline (866-755-6622) (noting that this hotline is a revised contact based on a request from GARFO, as the hotline provides continuous coverage throughout the region, and reports are collected by a NOAA biologist who would relay the report to the local stranding agreement holder as appropriate). NMFS does not find it appropriate to require direct reporting of
any
cetacean in any condition to the above reference hotline or local stranding hotlines on a daily basis. No serious injury or mortality is anticipated or proposed to be authorized for this activity, even in the absence of required mitigation measures, and such a measure would unnecessarily utilize Transco, NMFS, and local stranding network resources.
Comment 9:
In addition to consulting with Whale Alert, Whale Map, RWSAS, and VHF Ch. 16 as currently required, a commenter recommends that Transco also consult non-publicly available sources to enhance awareness of marine mammal presence in the project area. Sources highlighted include location stranding response groups, whale watching companies, research teams and relevant state offices to facilitate the exchange of knowledge of the most recent marine mammal sightings within and just outside the project area.
Response:
NMFS does not agree that the addition of the non-publicly available sources of information suggested by the commenter would result in improved awareness and information exchange beyond what will be achieved with the listed media and through Transco's requirements to report any North Atlantic right whale and any injured or dead marine mammal to the hotline. The existing requirements are considered comprehensive. For example, there is usually only a 24-hour lag between North Atlantic right whale reports and website updating on Whale Map, and the Northeast Marine Mammal and Sea Turtle Entanglement Hotline (866-755-6622) provides continuous coverage throughout the region, and reports are collected by a NOAA biologist who would relay the report to the local stranding agreement holder, as appropriate.
Comment 10:
A commenter requests more details regarding soft-start procedures such as the time period over which the three sets of strikes occur, the reduced energy level, and how long after the complete soft start procedure does impact pile driving occur.
Response:
NMFS thanks the commenter for its support of the soft start measure and its implementation at the start of impact pile driving on each day and at any time following cessation of impact pile driving for a period of 30 minutes or longer. Soft-start procedures are used to provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the hammer operating at full capacity. During a soft start for construction activities, NMFS requires a 30-second waiting period between reduced-energy strike sets. In the past, NMFS required a 1-minute waiting period between reduced-energy strike sets. PSOs reported that, in some cases, the 1-minute interval was too long, and marine mammals would leave the area but would return during the 1-minute quiet period. Therefore, the soft start measure was not accomplishing its intended effect, as marine mammals would not have left the area prior to the hammers operating at full capacity. Therefore, in this final IHA, NMFS continues to require a 30-second waiting period between reduced-energy strike sets during soft starts. As such, the soft start procedures should take about 60 seconds from first set to the third set and pile driving should commence within 90 seconds of the first soft-start set. Transco has indicated they will reduce strikes to a 25 percent capacity level for the initial strikes.
Comment 11:
Commenters provide concerns regarding the proposed authorization of take for North Atlantic right whales. A commenter stated that such authorization does not meet the MMPA's “least practicable adverse impact” standard and, therefore, that shutdowns must be implemented when any large whale is present within the Level B harassment zones.
Similarly, a commenter expresses concern by noting that the Potential Biological Removal (PBR) is less than 1 and that no North Atlantic right whale can be lost; that its resilience to future perturbations is expected to be low, that harassment can have population impacts, and that increased shipping traffic during construction pose a risk to North Atlantic right whale from both vessel strikes and underwater noise. The commenter recommends that NMFS deny authorization of all North Atlantic right whale takes.
Response:
We first note that commenters erroneously conflate the loss of individual right whales with the effects of behavioral harassment. The low-level, temporary instances of Level B harassment authorized through the IHA are not expected to cause energetic effects to the affected individuals, much less cause population-level impacts as would be required to reach the conclusions of commenters that the take of North Atlantic right whales contemplated here should not be authorized.
The MMPA requires that we include measures that will affect the least practicable adverse impact on the affected species and stocks and, in practice, NMFS agrees that the IHA should include conditions for the construction activities that will first avoid adverse effects on North Atlantic right whales in and around the project area, where practicable, and then minimize the effects that cannot be avoided.
No serious injury or mortality is anticipated or authorized. The project is planned to occur between June and November when North Atlantic right whales are less likely to be in the project area. Take by Level B harassment has been requested and authorized for North Atlantic right whales to account for potential for schedule shifts. NMFS has determined that this final IHA meets this requirement to effect the least practicable adverse impact.
NMFS is required to authorize the requested incidental take if it finds such incidental take of small numbers of marine mammals by the requestor while engaging in the specified activities
printed page 45735)
within the specified geographic region will have a negligible impact on such species or stock and where appropriate, will not have an unmitigable adverse impact on the availability of such species or stock for subsistence uses. As described in this notice of final IHA, NMFS finds that small numbers of marine mammals may be taken relative to the population size of the affected species or stocks and that the incidental take of marine mammal from Transco's specified activities will have a negligible impact on all affected marine mammal species or stocks.
Comment 12:
Two commenters question the need for the project, with one calling for re-evaluating the project necessity and exploration of less invasive alternatives of technologies, and the other suggesting that the tangible benefits do not outweigh the cost of disturbing natural resources.
Response:
NMFS is not authorizing the specified activities; rather, it is authorizing the take of marine mammals incidental to those activities. The MMPA requires that upon request, NMFS, as delegated by the Secretary of Commerce, issue an ITA if necessary findings are made (
e.g.,
negligible impact) and to prescribe (1) methods of taking pursuant to the specified activities, (2) means of effecting the least practicable adverse impact on marine mammals and their habitat (
i.e.,
mitigation measures), and (3) monitoring and reporting measures (
16 U.S.C. 1371(a)(5)(A)(i)
).
Changes From the Proposed IHA to the Final IHA
NMFS made corrections to several tables to address typographical errors. In table 6 of the proposed IHA
Federal Register
notice (
90 FR 38104
, August 7, 2025), the sound level (SPLrms) for vibratory installation of 60-in (1.5 m) steel piles was incorrectly listed as 193 dB. This typographical error has been corrected here in table 4 to clarify that the sound level analyzed is 195 dB. In table 7 of the proposed IHA
Federal Register
notice, under pile removal, the contents of “piles per day” and “duration to drive a single pile” columns were reversed for all piles. These typographical errors have been corrected here in table 5. In table 9 of the proposed IHA
Federal Register
notice, the Level B harassment isopleths (m) listed for vibratory installation of 48-in (1.2 m) steel, impact installation of 36-in (0.9 m) steel, and concurrent impact installation of two 36-in (0.9 m) steel piles were misarranged. These typographical errors have been corrected here in table 7 and in table 4 of the IHA. Also, in table 9 of the proposed IHA
Federal Register
notice, the Level A harassment zone (km
) for low frequency cetaceans during impact installation of 34-in (0.9 m) steel pile at MP 34.5/35.04 was misidentified. This typographical error has been corrected here in table 7. NMFS confirms that these were typographical errors and that the correct values were used in analysis in all cases. Given that the information used in the analysis did not change, these corrections do not change NMFS' analysis, findings, or determinations.
NMFS also corrected the IHA to require that injured and dead marine mammals be reported to the Northeast Marine Mammal and Sea Turtle Stranding and Entanglement Hotline (866-755-6622) rather than the Greater Atlantic Region/New England and Regional Stranding Coordinators that were listed in the proposed IHA.
In addition, NMFS has added clarifying language to certain IHA requirements: (1) Item 5.C. has been revised to specify that four PSOs would be employed at a pile driving location during concurrent pile driving, to meet the requirement of two PSOs being assigned at each active pile driving site; (2) Item 6.c.ii. of the IHA has been revised to specify that the combination of piles used during concurrent pile driving should be reported.
NMFS has also revised the IHA to include clarifications to proposed mitigation, monitoring, and/or reporting measures: (1) Item 6.c.v. of the IHA has been revised to include a requirement that Transco report whether/what mitigation is implemented for each marine mammal sighting, which was inadvertently omitted from the proposed IHA; and, (2) Transco must report any observations of North Atlantic right whales to NMFS and Right Whale Sightings Advisory System, or WhaleAlert. The report should include the time, date, and location of the sighting, number of whales, animal description/certainty of sighting (provide photos/video if taken), and PSO/reporter's contact information, and (3) as a result of public comment, Item 4 (e) of the IHA has been revised to increase the timeframe that monitoring must be conducted following a shutdown or delay due to the presence of a marine mammal within a shutdown zone, to 30 minutes for low-frequency cetaceans.
Transco agreed that these revised mitigation measures are practicable and monitoring and reporting measures are appropriate.
NMFS has made these adjustments in the final IHA. These changes do not affect our analysis, findings, or determinations.
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. NMFS fully considered all of this information, and we refer the reader to these descriptions, instead of reprinting the information. Additional information regarding population trends and threats may be found in NMFS' Stock Assessment Reports (SARs;
) and more general information about these species (
e.g.,
physical and behavioral descriptions) may be found on NMFS' website (
).
Table 1 lists all species or stocks for which take is expected and authorized for this activity and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and PBR, where known. PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS' SARs). While no serious injury or mortality is neither anticipated nor authorized here, PBR and annual serious injury and mortality (M/SI) from anthropogenic sources are included here as gross indicators of the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS' U.S. Atlantic SARs. All values presented in table 1 are the most recent available at the time of publication (including from the draft 2024 SARs) and are available online at:
printed page 45736)
Table 1—Species
With Estimated Take From the Specified Activities
Common name
Scientific name
Stock
ESA/
MMPA
status;
strategic

(Y/N)
Stock abundance
(CV, Nmin, most recent

abundance survey)
PBR
Annual M/SI
Order Artiodactyla—Cetacea—Mysticeti (baleen whales)
Family Balaenidae:
N Atlantic Right Whale
Eubalaena glacialis
Western Atlantic
E, D, Y
372 (0, 367, 2023)
0.73
14.8
Family Balaenopteridae (rorquals):
Fin Whale
Balaenoptera physalus
Western N Atlantic
E, D, Y
6,802 (0.24, 5,573, 2021)
11
2.05
Humpback Whale
Megaptera novaeangliae
Gulf of Maine
-, -, N
1,396 (0, 1380, 2016)
22
12.15
Minke Whale
Balaenoptera acutorostrata
Canadian Eastern Coastal
-, -, N
21,968 (0.31, 17,002, 2021)
170
9.4
Sei Whale
Balaenoptera borealis
Nova Scotia
E, D, Y
6,292 (1.02, 3,098, 2021)
6.2
0.6
Odontoceti (toothed whales, dolphins, and porpoises)
Family Delphinidae:
Long-Finned Pilot Whale
Globicephala melas
Western N Atlantic
-, -, N
39,215 (0.30, 30,627, 2021)
306
5.7
Short-Finned Pilot Whale
Globicephala macrorhynchus
Western N Atlantic
-, -, Y
18,726 (0.33, 14,292, 2021)
143
218
Atlantic Spotted Dolphin
Stenella frontalis
Western N Atlantic
-, -, N
31,506 (0.28, 25,042, 2021)
250
Atlantic White-Sided Dolphin
Lagenorhynchus acutus
Western N Atlantic
-, -, N
93,233 (0.71, 54,443, 2021)
544
28
Bottlenose Dolphin
Tursiops truncatus
Northern Migratory Coastal
-, -, Y
6,639 (0.41, 4,759, 2016)
48
12.2-21.5
Western N Atlantic Offshore
-, -, N
64,587 (0.24, 52,801, 2021)
507
28
Common Dolphin
Delphinus delphis
Western N Atlantic
-, -, N
93,100 (0.56, 59,897, 2021)
1,452
414
Family Phocoenidae (porpoises):
Harbor Porpoise
Phocoena phocoena
Gulf of Maine/Bay of Fundy
-, -, N
85,765 (0.53, 56,420, 2021)
649
145
Order Carnivora—Pinnipedia
Family Phocidae (earless seals):
Gray Seal
Halichoerus grypus
Western N Atlantic
-, -, N
27,911 (0.20, 23,624, 2021)
1,512
4,570
Harbor Seal
Phoca vitulina
Western N Atlantic
-, -, N
61,336 (0.08, 57,637, 2018)
1,729
339
Harp Seal
Pagophilus groenlandicus
Western N Atlantic
-, -, N
7.6M (UNK, 7.1M, 2019)
426,000
178,573
Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy (
).
Endangered Species Act 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.
NMFS marine mammal stock assessment reports online at:
CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
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, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
The current SAR includes an estimated population (N
est
372) based on sighting history through November 2023. In October 2024, NMFS released a technical report identifying that the North Atlantic right whale population size based on sighting history through 2023 was 372 whales, with a 95 percent credible interval ranging from 360 to 383 (Linden, 2024). Total annual average observed North Atlantic right whale mortality during the period 2018-2022 was 5.45 animals and annual average observed fishery mortality was 3.95 animals. Numbers presented in this table (14.8 total mortality and 10.8 fishery mortality) are 2018-2022 estimated annual means, accounting for undetected mortality and serious injury.
Key uncertainties exist in the population size estimate for this species, including uncertain separation between short-finned and long-finned pilot whales, small negative bias due to lack of abundance estimate in the region between U.S. and the Newfoundland/Labrador survey area, and uncertainty due to unknown precision and accuracy of the availability bias correction factor that was applied.
A key uncertainty exists in the population size estimate for this species based upon the assumption that the logistic regression model accurately represents the relative distribution of short-finned vs. long-finned pilot whales.
Estimates may include sightings of the coastal form.
NMFS' stock abundance estimate (and associated PBR value) applies to the U.S. population only. Total stock abundance (including animals in Canada) is approximately 394,311. The annual M/SI value given is for the total stock.
As indicated above, all 15 species (with 16 managed stocks) in table 1 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur.
In addition to what is included in sections 3 and 4 of the IHA application, and NMFS' website (
), further detail informing the regional occurrence for select species of particularly or unique vulnerability (
i.e.,
information regarding ESA listed or MMPA depleted species, information regarding current UMEs and known important habitat areas such as Biologically Important Areas (BIAs)) (Van Parijs, 2015) were provided in the
Federal Register
notice for the proposed IHA (
90 FR 38104
, August 7, 2025). Since publication of the notice of proposed IHA, we are not aware of any new relevant information; therefore, detailed descriptions are not provided here. Please refer to the
Federal Register
notice (
90 FR 38104
, Aug. 7, 2025) for these descriptions.
printed page 45737)
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities (
e.g.,
Richardson
et al.,
1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall
et al.,
(2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling,
etc.
). Generalized hearing ranges were chosen based on the ~65 decibel (dB) threshold from composite audiograms, previous analyses in NMFS (2018), and/or data from Southall
et al.
(2007) and Southall
et al.
(2019). We note that the names of two hearing groups and the generalized hearing ranges of all marine mammal hearing groups have been recently updated (NMFS 2024) as reflected below in table 2.
Table 2—Marine Mammal Hearing Groups
[NMFS, 2024]
Hearing group
Generalized
hearing range *
Low-frequency (LF) cetaceans (baleen whales)
7 Hz to 36 kHz.
High-frequency (HF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)
150 Hz to 160 kHz.
Very High-frequency (VHF) cetaceans (true porpoises,
Kogia,
river dolphins, Cephalorhynchid,
Lagenorhynchus cruciger
L. australis
200 Hz to 165 kHz.
Phocid pinnipeds (PW) (underwater) (true seals)
40 Hz to 90 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)
60 Hz to 68 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 may not be as broad. Generalized hearing range chosen based on ~65 dB threshold from composite audiogram, previous analysis in NMFS 2018, and/or data from Southall
et al.
2007; Southall
et al.
2019. Additionally, animals are able to detect very loud sounds above and below that “generalized” hearing range.
For more detail concerning these groups and associated frequency ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their Habitat
The effects of underwater noise from Transco's specified activities have the potential to result in behavioral harassment, and, in limited cases, an auditory threshold shift (TS), of marine mammals in the vicinity of the project area. The notice of proposed IHA (
90 FR 38104
, Aug. 7, 2025) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from Transco's specified activity on marine mammals and their habitat. NMFS is not aware of any new relevant information. Therefore, a discussion of potential effects is not repeated here; please refer to the
Federal Register
notice of the proposed IHA (
90 FR 38104
, Aug. 7, 2025).
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes authorized through the IHA, which informed NMFS' consideration of “small numbers,” the negligible impact determinations, and impacts on subsistence uses.
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 are primarily by Level B harassment, as use of the acoustic source/s (
i.e.,
impact and vibratory pile driving and removal) has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for auditory injury (AUD INJ) (Level A harassment) to result for all hearing groups. However, the planned mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is anticipated or authorized for this activity. Below we describe how the authorized take numbers were estimated.
For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic criteria above which NMFS believes there is some reasonable potential for marine mammals to be behaviorally harassed or incur some degree of AUD INJ; (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) the number of days of activities. We note that while these factors can contribute to a basic calculation to provide an initial prediction of potential takes, additional information that can qualitatively inform take estimates is also sometimes available (
e.g.,
previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the authorized take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria 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 AUD INJ of some degree (equated to Level A harassment). We note that the criteria for AUD INJ, as well as the names of two hearing groups, have been recently updated (NMFS 2024) as reflected below in the Level A harassment section.
Level B Harassment
—Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context (
e.g.,
frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment (
e.g.,
bathymetry, other noises in the area, predators in the area), and the receiving
printed page 45738)
animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict (
e.g.,
Southall
et al.,
2007, 2021, Ellison
et al.,
2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (root mean square, RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous (
e.g.,
vibratory pile driving, drilling) and above RMS SPL 160 dB re 1 μPa for non-explosive impulsive (
e.g.,
seismic airguns) or intermittent (
e.g.,
scientific sonar) sources. Generally speaking, Level B harassment take estimates based on these behavioral harassment thresholds are expected to include any likely takes by TTS as, in most cases, the likelihood of TTS occurs at distances from the source less than those at which behavioral harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as reduced hearing sensitivity and the potential reduced opportunities to detect important signals (conspecific communication, predators, prey) may result in changes in behavior patterns that would not otherwise occur.
Transco's planned activity includes the use of continuous (vibratory pile driving and removal) and impulsive (impact pile driving) sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1 μPa are applicable.
Level A Harassment
—NMFS' Updated Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 3.0) (Updated Technical Guidance, 2024) identifies dual criteria to assess AUD INJ (Level A harassment) to five different underwater marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). Transco's planned activity includes the use of impulsive (impact pile driving) and non-impulsive (vibratory pile driving and removal) sources.
The 2024 Updated Technical Guidance criteria include both updated thresholds and updated weighting functions for each hearing group. The thresholds are provided in the table below. The references, analysis, and methodology used in the development of the criteria are described in NMFS' 2024 Updated Technical Guidance, which may be accessed at:
Table 3—Thresholds Identifying the Onset of Auditory Injury
Hearing group
AUD INJ onset acoustic thresholds *
(received level)
Impulsive
Non-impulsive
Low-Frequency (LF) Cetaceans
Cell 1:
pk,flat
: 222 dB;
E,
LF,24h
: 183 dB
Cell 2:
E,
LF,24h
: 197 dB.
High-Frequency (HF) Cetaceans
Cell 3:
pk,flat
: 230 dB;
E,
HF,24h
: 193 dB
Cell 4:
E,
HF,24h
: 201 dB.
Very High-Frequency (VHF) Cetaceans
Cell 5:
pk,flat
: 202 dB;
E,
VHF,24h
: 159 dB
Cell 6:
E,
VHF,24h
: 181 dB.
Phocid Pinnipeds (PW); (Underwater)
Cell 7:
pk,flat
: 223 dB;
E,
PW,24h
: 183 dB
Cell 8:
E,
PW,24h
: 195 dB.
Otariid Pinnipeds (OW); (Underwater)
Cell 9:
pk,flat
: 230 dB;
E,
OW,24h
: 185 dB
Cell 10:
E,
OW,24h
: 199 dB.
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-impulsive sources.
Note
: Peak sound pressure level (
p,0-pk
) has a reference value of 1 µPa, and weighted cumulative sound exposure level (
E,p
) has a reference value of 1 µPa
s. In this table, criteria are abbreviated to be more reflective of International Organization for Standardization standards (ISO 2017). The subscript “flat” is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized hearing range of marine mammals underwater (
i.e.,
7 Hertz (Hz) to 165 Kilohertz (kHz)). The subscript associated with cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The weighted cumulative sound exposure level criteria 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 criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and transmission loss coefficient.
The sound field in the project area is the existing background noise plus additional construction noise from the planned project. Marine mammals are expected to be affected via sound generated by the primary components of the project (
i.e.,
vibratory pile driving and removal, and impact pile driving).
The project includes vibratory pile installation and removal, and impact pile driving. Since there would be many piles at each of the eight construction sites within close proximity to one another, Transco found, and NMFS agreed, that it was not practical to estimate harassment zones for each individual pile at specific locations and results would have been nearly identical for all similarly sized piles at each construction location. In order to simplify calculations, a representative pile site was selected for the eight separate pile locations (figure 1). For strings where only a single pile type would be installed or removed (
i.e.,
Neptune Power Cable Crossing MP 13.84 and MP 35.04, MP 14.5 to MP 16.5, MP 28 to MP 29.36, and MP 34.5 to MP 35.04), Transco selected a representative location in the middle of the string. For the Morgan Shore Approach HDD string site, Transco selected the location closest to the platform installation as the representative pile location because it represents the area with the largest pile sizes. At the HDD Ambrose West Side and HDD Ambrose East Side locations, Transco's representative pile locations were selected based on the entry and exit pits. The HDD Ambrose East Side is the entry pit and the HDD Ambrose West Side is the exit pit. This would also represent the outer limit of the HDD Ambrose string, and is therefore the most conservative modeling option.
In its application, Transco indicated that it identified source levels for installation and removal of each pile type and size using the compendium
printed page 45739)
compiled by Caltrans 2015, but also referenced Caltrans, 2020 and Illingworth & Rodkin, 2017. Transco did not specify which sound levels were based on which reference. NMFS revised source levels for these activities based on reviews of measurements of the same or similar types and dimensions of piles available in the literature (table 4). NMFS and Transco assumed that the representative sound source levels were based on the largest pile expected to be driven/removed at each potential in-water construction site. For example, where Transco may use a range of pile sizes (
i.e.,
36 to 48-in (0.9 to 1.2 m) piles), the largest potential pile size (48-in (1.2 m)) was used in modeling. Source levels for vibratory installation and removal are assumed to be the same.
Additionally, while not included in its application, Transco indicated that two hammers, including a combination of vibratory and impact hammers, may operate simultaneously at three out of eight locations. As such, source levels for the combination of piles that would create the largest cumulative sound exposure level at location are also presented in table 4.
The methods for how the source levels for these concurrent activities are derived are described here: When two noise sources have overlapping sound fields, the sources are considered additive and combined using the rules of dB addition. For addition of two simultaneous sources, the difference between the two sound source levels is calculated, and if that difference is between 0 and 1 dB, 3 dB are added to the higher sound source levels; if the difference is between 2 and 3 dB, 2 dB are added to the highest sound source levels; if the difference is between 4 and 9 dB, 1 dB is added to the highest sound source levels; and with differences of 10 or more dB, there is no addition. For two simultaneous sources of different type (
i.e.,
impact and vibratory driving), there is no sound source addition. In such cases, the isopleth associated with the individual source which results in the largest isopleths is conservatively used for both sources to account for periods of overlapping activities.
Table 4—Estimates of Mean Underwater Sound Levels
Generated During Vibratory and Impact Pile Driving and Vibratory Removal of Temporary Steel Piles
Method
Pile size
(inches)
dB RMS
dB Peak
dB SEL
References
Vibratory
10
155
N/A
N/A
Caltrans 2015.
24
157
N/A
N/A
Caltrans 2020.
34
170
N/A
N/A
Caltrans 2015.
36
170
N/A
N/A
Caltrans 2015.
48
170
N/A
N/A
NMFS 2024.
60
170
N/A
N/A
NMFS 2024.
Impact
34
193
210
183
Caltrans 2015, Caltrans 2020.
36
193
210
183
Caltrans 2015, Caltrans 2020.
60
195
210
185
Caltrans 2020.
Impact, Impact
36, 36
196
213
183
Caltrans 2015.
Impact, Vibratory
60, 48
170
210
185
Caltrans 2020.
Vibratory, Vibratory
48, 48
173
N/A
N/A
NMFS 2024.
36, 36
173
N/A
N/A
36, 48
173
N/A
N/A
Note:
dB peak = peak sound level; rms = root mean square; SEL = sound exposure level.
All sound levels are referenced at 10 m.
Refers to a NMFS compendium of recommended source level proxies.
Source levels adjusted following rules of dB addition described above.
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
× Log10 (
),
where:
TL
= transmission loss in dB
= transmission loss coefficient
= the distance of the modeled SPL from the driven pile, and
= the distance from the driven pile of the initial measurement
Absent site-specific acoustical monitoring with differing measured
TL,
a practical spreading value of 15 is used as the
TL
coefficient in the above formula. Site-specific
TL
data for the New York Bight are not available; therefore, the default coefficient of 15 is used to determine the distances to the Level A harassment and Level B harassment thresholds.
The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the 2024 Updated Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources pile driving and removal, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur AUD INJ. Inputs used in the optional User Spreadsheet tool, and the resulting estimated isopleths, are reported in tables 5 and 6.
To calculate Level A harassment isopleths for two impact hammers operating simultaneously, the NMFS User Spreadsheet calculator was used with modified inputs to account for the total estimated number of strikes for all piles. For simultaneous impact pile driving of two 36-in (0.9 m) steel piles (the most conservative scenario identified at Morgan Shore Approach HDD MP 12.59), the total estimated number of strikes per day was summed
printed page 45740)
to estimate total sound exposure during simultaneous installation, and the number of piles per day was reduced to one. The source level for two simultaneous impact hammers was not adjusted because for identical sources the accumulation of energy depends only on the total number of strikes, whether or not they overlap fully in time.
To calculate the Level A harassment isopleths for one impact and one vibratory hammer operating simultaneously, sources were treated as though they were non-overlapping. The isopleths associated with the individual source which results in the largest Level A harassment isopleths were conservatively used for both sources to account for periods of overlapping activities.
To calculate Level A harassment isopleths for two simultaneous vibratory hammers, the NMFS User Spreadsheet was used with modified inputs to account for accumulation, weighting, and source overlap in space and time. Using the rules of dB addition described above (
i.e.,
if the difference between the two source levels is between 0 and 1 dB, 3 dB are added to the higher sound source level), the combined sound source level for the simultaneous vibratory installation of two 48-in steel piles, or two 36-in (0.9 m) steel piles, or a 36-in (0.9 m) and a 48-in (1.2 m) steel pile is 173 dB RMS in all cases.
Table 5—User Spreadsheet Inputs—Single Pile Driving Scenarios
Location
Pile size
Spreadsheet tab used
Weighting
factor
adjustment
(kHz)
Piles
per day
Duration to
drive a
single pile
(minutes)
Strikes
Installation
Morgan Shore Approach HDD (MP 12.59)
24
36
48
A.1 Vibratory pile driving
2.5
15
N/A
36
E.1 Impact pile driving
N/A
2,500
Neptune Power Cable Crossing (MP 13.84)
10
A.1 Vibratory pile driving
2.5
15
N/A
MP 14.5 to MP 16.5
24
A.1 Vibratory pile driving
2.5
15
N/A
MP 28.0 to MP 29.36
34
A.1 Vibratory pile driving
2.5
15
N/A
HDD Ambrose West Side (MP 29.4)
24
36
48
60
A.1 Vibratory pile driving
2.5
15
N/A
E.1 Impact pile driving
N/A
3,382
HDD Ambrose East Side (MP 30.48)
24
36
48
60
A.1 Vibratory pile driving
2.5
15
N/A
MP 34.5 to MP 35.04
34
A.1 Vibratory pile driving
2.5
15
N/A
E.1 Impact pile driving
15
2,500
Neptune PC Crossing (MP 35.04)
10
A.1 Vibratory pile driving
2.5
15
N/A
Removal
Morgan Shore Approach HDD (MP 12.59)
24
36
48
A.1 Vibratory pile driving
2.5
30
15
N/A
Neptune PC Crossing (MP 13.84)
10
A.1 Vibratory pile driving
2.5
15
N/A
MP 14.5 to MP 16.5
24
A.1 Vibratory pile driving
2.5
11
15
N/A
MP 28.0 to MP 29.36
34
A.1 Vibratory pile driving
2.5
30
N/A
HDD Ambrose West Side (MP 29.4)
24
36
48
60
A.1 Vibratory pile driving
2.5
15
15
30
N/A
HDD Ambrose East Side (MP 30.48)
24
36
48
60
A.1 Vibratory pile driving
2.5
22
15
N/A
MP 34.5 to MP 35.04
34
A.1 Vibratory pile driving
2.5
15
N/A
Neptune PC Crossing (35.04)
10
A.1 Vibratory pile driving
2.5
15
N/A
Table 6—User Spreadsheet Inputs: Simultaneous Pile Driving Scenarios
Location
Pile sizes
(inches)
and methods
Spreadsheet tab used
Weighting
factor
adjustment
(kHz)
Piles
per day
Duration to
drive a
single pile
(minutes)
Strikes
Installation
Morgan Shore Approach HDD (MP 12.59)
36 impact, 36 impact
E.1 Impact pile driving
N/A
15,000
HDD Ambrose West Side (MP 29.4)
60 impact, 48 vibratory
E.1 Impact pile driving
N/A
3,382
HDD Ambrose East Side (MP 30.48)
48 vibratory, 48 vibratory
A.1 Vibratory pile driving
2.5
60
N/A
Removal
Morgan Shore Approach HDD (MP 12.59)
36 vibratory, 36 vibratory
A.1 Vibratory pile driving
2.5
40
N/A
HDD Ambrose West Side (MP 29.4)
36 vibratory, 48 vibratory
A.1 Vibratory pile driving
2.5
60
N/A
HDD Ambrose East Side (MP 30.48)
48 vibratory, 48 vibratory
A.1 Vibratory pile driving
2.5
60
N/A
printed page 45741)
NMFS recommends use of Level B harassment thresholds of 160 dB re1μPa (rms) for impulsive sounds (
e.g.,
impact pile driving) and 120 dB re1μPa (rms) for non-impulsive sounds (
e.g.,
vibratory driving and removal). Based on the predicted source levels associated with various pile sizes (table 4) the distances from the pile driving/removal equipment to the Level B harassment thresholds were calculated, using the distance to the 160 dB threshold for the impact hammer and the distance to the 120 dB threshold for the vibratory device, at the representative pile locations (table 7). It should be noted that while sound levels associated with the Level B harassment threshold for vibratory driving/removal were estimated to propagate as far as 34,146 m from pile installation and removal activities based on modeling, it is likely that the noise produced from vibratory activities associated with the project would be masked by background noise before reaching this distance, as the Port of New York and New Jersey, which represents the busiest port on the east coast of the United States and the third busiest port in the United States, is located near the project area and sounds from the port and from vessel traffic propagate throughout the project area. However, take estimates conservatively assume propagation of project-related noise to the full extent of the modeled isopleth distance to the Level B harassment threshold. The modeled distances to isopleths associated with Level B harassment thresholds for impact and vibratory driving are shown in table 9.
Table 7—Projected Distances to Level A and Level B Harassment Isopleths
(m)
(and Associated Areas
(km

by Marine Mammal Hearing Group
Location
Pile size
(inches)
Hammer type
Level A harassment zones (m) (areas km
Level B
harassment
zone
LF
HF
VHF
PW
Installation
Morgan Shore Approach HDD (MP 12.59)
24
36
48
Vibratory
36.7
36.7
1.9
14.1
14.1
4.1
30.0
30.0
6.4
47.3
47.3
2,929
21,544
21,544
36
Impact
4,618.4
589.3
7,147.0
4,102.8
1,585
36 and 36
Impact and Impact
6,052 (34.20)
772 (1.72)
9,365 (59.13)
5,376 (29.19)
2,512
Neptune PC Crossing (MP 13.84)
10
Vibratory
3.7
1.4
3.0
4.7
2,154
MP 14.5 to MP 16.5
24
Vibratory
5.8
2.2
4.7
7.5
2,929
MP 28.0 to MP 29.36
34
Vibratory
36.7
14.1
30.0
47.3
21,544
HDD Ambrose West Side (MP 29.4)
24
36
48
60
Vibratory
6.5
23.1
36.7
23.1
2.5
8.9
14.1
8.9
5.3
18.9
30.0
18.9
8.4
29.8
47.3
29.8
2,929
21,544
21,544
21,544
Impact
4,837.6
617.2
7,486.1
4,297.5
2,154
60 and 48
Impact and Vibratory
4,837.6 (72.22)
617.2 (1.20)
7,486.1 (159.37)
4,297.5 (57.63)
34,146 (1,502)
HDD Ambrose East Side (MP 30.48)
24
36
48
60
Vibratory
5.8
30.3
58.3
14.6
2.2
11.6
22.4
5.6
4.7
24.8
47.6
11.9
7.5
39.0
75.0
18.8
2,929
21,544
21,544
21,544
21,544
48 and 48
Vibratory and Vibratory
58.3
22.4
47.6
75.0
34,146 (1,502)
MP 34.5 to MP 35.04
34
Vibratory
23.1
8.9
18.9
29.8
21,544
Impact
2,909.4 (26.59)
371.2 (0.43)
4,502.3 (62.49)
2,584.6 (20.99)
1,585
Neptune PC Crossing (MP 35.04)
10
Vibratory
2.3
0.9
1.9
3.0
2,154 (14.58)
Removal
Morgan Shore Approach HDD (MP 12.59)
24
36
48
Vibratory
2.4
92.5
30.3
0.9
35.5
11.6
2.0
75.6
24.8
3.1
119.1
39.0
2,929
21,544
21,544
36 and 36
Vibratory and Vibratory
44.4
17.1
36.3
57.2
34,146 (1,539)
Neptune PC Crossing (MP 13.84)
10
Vibratory
3.7
1.4
3.0
4.7
2,154
MP 14.5 to MP 16.5
24
Vibratory
9.8
3.8
8.0
12.6
2,929
MP 28.0 to MP 29.36
34
Vibratory
76.4
29.8
62.4
98.3
21,544
HDD Ambrose West Side (MP 29.4)
24
36
48
60
Vibratory
3.1
30.3
58.3
92.5
1.2
11.6
22.4
35.5
2.6
24.8
47.6
75.6
4.0
39.0
75.0
119.1
2,929
21,544
21,544
21,544
36 and 48
Vibratory and Vibratory
58.3
22.4
47.6
75.0
34,146
HDD Ambrose East Side (MP 30.48)
24
36
48
60
Vibratory
15.6
30.3
58.3
14.6
6.0
11.6
22.4
5.6
12.7
24.8
47.6
11.9
20.0
39.0
75.0
18.8
2,929
21,544
21,544
21,544
48 and 48
Vibratory and Vibratory
58.3
22.4
47.6
75.0
34,146
MP 34.5 to MP 35.04
34
Vibratory
23.1
8.9
18.9
29.8
21,544
Neptune PC Crossing (35.04)
10
Vibratory
2.3
0.9
1.9
3.0
2,154
Only areas relevant for take estimates (the largest Level B harassment zones at each location, and the largest Level A harassment zones associated with impact pile driving at each location) are presented.
printed page 45742)
Level A harassment zones are typically smaller than Level B harassment zones. However, during impact pile driving, the calculated Level A harassment isopleth is greater than the calculated Level B harassment isopleth for low frequency cetaceans, very high-frequency cetaceans and phocids (however, because all activities are assumed as potentially occurring on the same day, we functionally reference the largest Level A and Level B harassment zones for purposes of estimating take). Calculation of Level A harassment isopleths includes a duration component, which in the case of impact pile driving, is estimated through the total number of daily strikes and the associated pulse duration. For a stationary sound source such as impact pile driving, we assume here that an animal is exposed to all of the strikes expected within a 24-hour period. Calculation of a Level B harassment zone does not include a duration component.
Marine Mammal Occurrence
In this section we provide information about the occurrence of marine mammals, including density or other relevant information which will inform the take calculations. Additionally, we describe how the occurrence information is synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and authorized.
To estimate take during impact and vibratory pile driving and removal, Transco first generated an annual average density estimate for each noise-producing scenario, for each species, using Duke University Marine Geospatial Ecology Laboratory marine mammal habitat-based density data (
) (Roberts
et al.,
2016; Roberts
et al.,
2023, Roberts
et al.,
2024). Instead of generating average annual density estimates for each species for each noise producing scenario, NMFS subsequently created a single project area that encompassed the largest Level B harassment zones across each of the eight project locations. This project area was used as the basis for generating an annual average density estimate and an average density estimate between June and November, which corresponds to the planned project period, for each species. Specifically, in a Geographic Information System, for each month and each species, the density rasters were clipped to the polygon representing the above referenced project area. To generate the annual average density estimate for each species, the density estimates for each clipped density raster (January through December) were summed and divided by 12 (table 8). To generate the average density across June through November, the density values for each clipped density raster (June through November) were summed and divided by 6. In both cases, the mean density values for each species were selected to use as a basis for take estimates.
Table 8—Marine Mammal Density Estimates Generated for the Transco Northeast Supply Enhancement Project Area
Marine mammal species
Mean densities
(January-December)

animals/100 km
Mean densities
(June-November)

animals/100 km
North Atlantic Right Whale
0.021304616299007
0.0030074206269121
Fin Whale
0.034273800129881
0.019738282989868
Humpback Whale
0.057397781000022
0.032971508482719
Minke Whale
0.094349173218718
0.027476606940787
Sei Whale
0.013016774291886
0.0056379703117625
Pilot Whale spp guild
0.0010383579896433
0.0010383579896433
Atlantic Spotted Dolphin
0.012827813937997
0.025403273029717
Atlantic White-Sided Dolphin
0.1092249846683
0.068747673449369
Bottlenose Dolphin
5.2491380360819
8.0931224515361
Common Dolphin
0.9122067405692
0.63518957481269
Harbor Porpoise
0.8396537609158
0.022988098221005
Seal guild
8.6582116388505
8.0272698748496
The Duke University density data treats all bottlenose dolphins as a single group and as such are not subset between the Migratory Coastal stocks and the Offshore stocks by the 20-meter isobath.
The Duke University density data for pilot whale
spp.
is not broken up for each species and only a single density file is available. The density here represents the entire guild and will be the same for the annual mean or the June to November analysis.
The Duke University data for pinnipeds is not broken up for each species that could occur and represents the density for the guild.
In addition to consulting the output of marine mammal habitat-based density models, NMFS also consulted the following data sets: (1) Monitoring data associated with Transco's LNYBL Maintenance Project in Sandy Hook Channel, New Jersey, in which PSO's monitored for marine mammals on 59 days between mid-July and late October 2024 in Raritan and Lower New York Bays; and, (2) group sizes derived from NOAA Atlantic Marine Assessment Program for Protected Species data from 2010 to 2019 shipboard distance sampling surveys (Palka
et al.,
2021).
Take Estimation
Here we describe how the information provided above is synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and authorized. Generally, take estimates are the product of density, ensonified area, and number of days of pile driving work. Specifically, take estimates are calculated by multiplying the expected densities of marine mammals in the activity area(s) by the area of water likely to be ensonified above the NMFS defined threshold levels in a single day (24-hr period) and the number of construction days planned. A summary of this method is illustrated in the following formula:
Estimated Take
ZOI
× #
of construction days
Where:
D =
density estimate for each species (individuals/km
) within the ZOI. (Note that since densities in Roberts
et al.
(2023, 2024) are provided in individuals per 100 square km, they were converted to individuals per square km for ease of use in generating take estimates).
ZOI =
maximum daily ensonified area to relevant thresholds (km
To estimate take, Transco initially multiplied the location-specific annual average density estimates for each
printed page 45743)
species by the ZOI associated with each noise-producing activity, by the number of construction days estimated for each noise-producing activity (based on pile size and location). Activity-specific take estimates were then summed to generate an overall take estimate for each species across the project.
Because any activity could occur on any construction day, NMFS instead multiplied the density estimate generated for the entire project area by the largest ZOI associated with each of the eight project locations by the total number of construction days planned at each location. The resulting location-specific take estimates were summed to generate an overall take estimate for each species across the project. To be conservative, NMFS compared the results using the annual average density estimate for each species and the average density estimate for June through November and selected the largest result to use as the basis for its take authorization.
NMFS used the same equation to calculate take by Level A harassment, with the ZOIs referring to the largest hearing group specific Level A harassment zones at each location, during impact pile driving activities only. Because Transco plans to shut down at distances greater than the Level A harassment zones during vibratory activities, only impact pile driving activities were included in estimates of take by Level A harassment.
The ZOI's and total construction days used in density-based take analyses are presented in the tables 9 and 10.
Table 9—The ZOI's and Total Construction Days Used in Density-Based Estimates of Take by Level B Harassment
Location
ZOIs at each representative

pile driving location (km

(and associated isopleths (m))
Total construction days associated
with vibratory pile driving

(installation and removal)
at each

representative pile driving location
(and associated isopleths (m))
Morgan Shore Approach HDD (MP 12.59)
373 km
(34,146 m)
21
Neptune Power Cable Crossing (MP 13.84)
15 km
(2,154 m)
MP 14.5 to MP 16.5
24 km
(2,929 m)
MP 28.0 to MP 29.36
761 km
(21,544 m)
HDD Ambrose West Side (MP 29.4)
1502 km
(34,146 m)
13
HDD Ambrose East Side (MP 30.48)
1502 km
(34,146 m)
14
MP 34.5 to MP 35.04
857 km
(21,544 m)
Neptune Power Cable Crossing (MP 35.04)
15 km
(2,154 m)
Total construction days have been rounded up.
Table 10—The ZOI's and Total Construction Days Used in Density-Based Estimates of Take by Level A Harassment
Location
ZOI representing the largest hearing group specific Level A harassment zones (km
at each location during impact pile driving (and associated isopleths (m)
Total construction days associated with impact pile driving
LF
HF
VHF
PW
Morgan Shore Approach HDD (MP 12.59)
34.2 km
(6,052 m)
1.72 km
(722 m)
59.13 km
(9,365 m)
29.19 km
(5,376 m)
HDD Ambrose West Side (MP 29.4)
72.23 km
(4,838 m)
1.20 km
(617 m)
159.37 km
(7,486 m)
57.63 km
(4,298 m)
MP 34.5 to MP 35.04
26.59 km
(2,909 m)
0.43 km
(371 m)
62.49 km
(4,502 m)
20.99 km
(2,585 m)
Total construction days have been rounded up.
Monitoring data reported by PSO's during Transco's LNYBL Maintenance project in Raritan Bay, Lower New York Bay, and the Atlantic Ocean, in which PSOs monitored for marine mammals on 59 days between July and October 2024, were also consulted to inform estimates of take by Level A harassment.
A total of eight sightings of 10 humpback whales were observed within 4,000 m of the pile driving source, translating to approximately one sighting of humpback whales per week. The maximum group size reported during this project was two humpback whales. As such, NMFS has authorized take by Level A harassment of one group of two humpback whales each week that impact pile driving activities are planned (two weeks). Therefore, NMFS has authorized four takes by Level A harassment of humpback whale (1 group × 2 humpback whales × 2 weeks of impact pile driving).
During Transco's LNYBL project, PSOs also reported an average of six bottlenose or unidentified dolphins each day occurring within 770 m of the pile driving source, which represents the largest Level A harassment zones associated with impact pile driving for this project. As such, NMFS has authorized six takes by Level A harassment for each construction day that impact pile driving is planned (14 days). Therefore, NMFS has authorized 84 takes by Level A harassment of bottlenose dolphins (6 takes of bottlenose dolphins × 14 construction days = 84 takes by Level A harassment of bottlenose dolphin).
Additional data regarding average group sizes from survey effort in the region was considered to ensure adequate take estimates are evaluated. Take estimates for several species were adjusted based on average group sizes derived from NOAA Atlantic Marine Assessment Program for Protected Species data from 2010 to 2019 shipboard distance sampling surveys (Palka
et al.,
2021). This is particularly true for uncommon or rare species with very low densities in the models. The calculated take estimates were adjusted for species as follows:
Pilot whales (long-finned and short-finned): Only one take by Level B harassment was estimated. Authorized takes were increased to the average number of pilot whales in a group reported in Palka
et al.
2021 (n = 14) and applied to both stocks; and
Atlantic spotted dolphin: Only 14 takes by Level B harassment were estimated. Authorized takes were increased to the average number of dolphins in a group reported in Palka
et al.,
2021 (n = 25).
For bottlenose dolphins, the density data presented by Roberts
et al.
(2023, 2024) does not differentiate between
printed page 45744)
stocks. Thus, the take estimate for bottlenose dolphins calculated by the method described above resulted in an estimate of the total number of bottlenose dolphins expected to be taken, from all stocks. However, as described above, both the Western North Atlantic Northern Migratory Coastal stock and the Western North Atlantic Offshore stock have the potential to occur in the project area. Because approximately 50 percent of the project area occurs in waters shallower than 20 m, the isobaths at which we expect segregation of these stocks (Garrison
et al.,
2017), we assign take to each stock accordingly. Thus, we assume that 50 percent of the total authorized bottlenose dolphin takes would accrue to the Western North Atlantic Offshore stock, and 50 percent to the Western North Atlantic Northern Migratory Coastal stock (table 11).
Finally, takes by Level B harassment are modified to deduct the amount of take by Level A harassment in order to avoid double-counting in the estimate of total takes for each species or stock.
Table 11—Take by Stock and Harassment Type and as a Percentage of Stock Abundance
Species
Stock
Level B
take
authorized
Level A
take
authorized
Total take
authorized
% Stock
North Atlantic Right Whale
Western Atlantic
12
12
<3.2
Fin Whale
Western North Atlantic
19
19
<1
Humpback Whale
Gulf of Maine
29
33
<1
Minke Whale
Canadian East Coast
53
54
<1
Sei Whale
Nova Scotia
<1
Pilot Whale, Long-finned
Western N Atlantic
14
14
<1
Pilot Whale, Short-finned
Western N Atlantic
Atlantic Spotted Dolphin
Western N Atlantic
25
25
<1
Atlantic White-sided Dolphin
Western N Atlantic
62
62
<1
Bottlenose Dolphin
Western N Atlantic Migratory Coastal
2,295
42
2,253
35
Western N Atlantic Offshore
2,296
42
2,254
3.5
Common Dolphin
Western N Atlantic
518
518
<1
Harbor Porpoise
Gulf of Maine/Bay of Fundy
465
11
465
<1
Gray Seal
Western N Atlantic
4,868
44
4,912
17.6
Harbor Seal
Western N Atlantic
Harp Seal
Western N Atlantic
<1
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, NMFS considers 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, and impact on operations.
The mitigation requirements described in the following were proposed by Transco in its adequate and complete application or are the result of subsequent coordination between NMFS and Transco. Transco has agreed that all of the mitigation measures are practicable. NMFS has fully reviewed the specified activities and the mitigation measures to determine if the mitigation measures would result in the least practicable adverse impact on marine mammals and their habitat, as required by the MMPA, and has determined the measures are appropriate. NMFS describes these below as mitigation requirements, and has included them in the issued IHA.
Vessel Strike Avoidance Measures
In addition to complying with existing vessel speed restrictions for North Atlantic right whales, Transco intends to comply with voluntary programs NMFS uses to notify vessel operators to slow down to avoid right whales. All project related vessels, regardless of size, will operate at 10 knots (18.5 km/hr) or less when traveling in an SMA (active in portions of the project area between November 1 and April 30). Additionally, at all times and locations, vessel operators and crews would use the following protocols:
Maintain a vigilant watch for right whales and slow down or stop the vessel to avoid striking the animal(s);
Conform to the regulations prohibiting approach of right whales closer than 500 yards (460 m) (
50 CFR 224.103(c)
);
Adhere to rules for DMAs if they are designated by NMFS in the project area during the project.
Shutdown Zones
For all pile driving and removal activities, Transco would implement shutdowns within designated zones. 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
printed page 45745)
in anticipation of an animal entering the defined area). Shutdown zones vary based on the activity type and marine mammal hearing group (tables 12 and 13).
In cases where it would be challenging to detect marine mammals at the Level A harassment isopleth, (
e.g.,
all hearing groups during impact pile driving activities), and where shutting down at the Level A harassment zone would create practicability concerns due to the distances at which species would need to be detected (
e.g.,
high frequency cetaceans during impact pile driving), smaller shutdown zones have been established (table 13).
Construction supervisors and crews, PSOs, and relevant Transco staff must 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, as necessary to avoid direct physical interaction. If an activity 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 indicated in tables 12 and 13, or 30 minutes (low-frequency cetaceans) or 15 minutes (all other marine mammals) have passed without re-detection of the animal.
Finally, construction activities must be halted upon observation of 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 any harassment zone. If a marine mammal species for which take is not authorized enters a harassment zone, all in-water activities will cease until the animal leaves the zone or has not been observed for at least 30 minutes (low-frequency cetaceans) or 15 minutes (all other marine mammals). Pile driving will proceed if the unauthorized species is observed leaving the harassment zone or if 30 minutes (low frequency cetaceans) or 15 minutes (all other marine mammals) have passed since the last observation.
Table 12—Shutdown Zones During Vibratory Pile Driving and Removal
Site
Pile size
(inches)
Installation or
removal method
Shutdown for all
hearing groups,
install and removal
(m)
Morgan Shore Approach HDD (MP 12.59)
24
Vibratory
10
36
Vibratory
120
36, 36
Vibratory, Vibratory
60
48
Vibratory
50
Neptune PC Crossing (MP 13.84)
10
Vibratory
10
MP 14.5 to MP 16.5
24
Vibratory
20
MP 28.0 to MP 29.36
34
Vibratory
100
HDD Ambrose West Side (MP 29.4)
24
Vibratory
10
36
Vibratory
40
48
Vibratory
80
36, 48
Vibratory, Vibratory
80
60
Vibratory
120
HDD Ambrose East Side (MP 30.48)
24
Vibratory
20
36
Vibratory
40
48
Vibratory
80
48, 48
Vibratory, Vibratory
80
60
Vibratory
20
MP 34.5 to MP 35.04
34
Vibratory
30
Neptune PC Crossing (MP 35.04)
10
Vibratory
10
Table 13—Shutdown Zones During Impact Pile Driving
[m]
Location
Pile types
Activity
Hearing group-specific shutdown zones (m)
LF
HF
VHF
PW
HDD Morgan Offshore (MP 12.59)
36-in
Impact
2,000
200
200
150
36, 36
Impact, Impact
60
Impact
HDD Ambrose West Side (MP 29.4)
60, 48
Impact, Vibratory
MP 34.5 to MP 35.04
34
Impact
PSOs
The number and placement of PSOs during all construction activities (described in the Monitoring and Reporting section) would ensure that the shutdown zones are generally visible, such that PSOs are reasonably confident of their ability to observe species at relevant distances. Transco would employ at least two PSOs at each active pile driving site during all pile driving activities.
Monitoring for Level A and Level B Harassment
PSOs would monitor the shutdown zones and beyond to the extent that PSOs can see. Monitoring beyond the shutdown zones enables observers to be aware of and communicate the presence of marine mammals in the project areas outside the shutdown zones and thus prepare for a potential cessation of activity should the animal enter the shutdown zone. Transco also plans to take measures beyond visual observations to ensure that they are
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aware of marine mammal locations by monitoring media throughout the day including, but not limited to, Whale Alert, Whale Map, Right Whale Sightings Advisory System (RWSAS), and U.S. Coast Guard very high frequency (VHF) Channel 16 (see Monitoring and Reporting section).
Pre-and-Post-Activity Monitoring
Prior to the start of daily in-water construction activity, or whenever a break in pile driving of 30 minutes or longer occurs, PSOs would observe the shutdown zones and as much of the harassment zones as possible for a period of 30 minutes. Pre-start clearance monitoring must be conducted during periods of visibility sufficient for the lead PSO to determine that the shutdown zones are clear of marine mammals for which take is authorized. If the shutdown zone for which take is authorized is obscured by fog or poor lighting conditions, in-water construction activity will not be initiated until the entire shutdown zone is visible. Pile driving may commence following 30 minutes of observation when the determination is made that the shutdown zones are clear of marine mammals. If a marine mammal is observed entering or within shutdown zones, pile driving activity must be delayed or halted. 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. If a marine mammal for which take by Level B harassment is authorized is present in the Level B harassment zone, activities may begin. If work ceases for more than 30 minutes, the pre-activity monitoring of the shutdown zones would commence.
Soft Start
The use of soft-start procedures during impact pile driving are believed to provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the hammer operating at full capacity. For impact pile driving, contractors would be required to provide an initial set of three strikes from the hammer at reduced energy, with each strike followed by a 30-second waiting period. This procedure would be conducted a total of three times before impact pile driving begins. Soft start would 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. As such, soft start procedures are expected to be completed within 60 seconds from the first set to the third set and pile driving should commence within 90 seconds of the first soft-start set. Transco will reduce energy levels of strikes to 25 percent during soft start procedures. Soft start is not required during vibratory pile driving activities.
Based on our evaluation of the applicant's planned measures, as well as other measures considered by NMFS, NMFS has determined that the mitigation measures provide the means of 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.
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 while conducting the activities. 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 activity; 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.
The monitoring and reporting requirements described in the following were proposed by Transco in its adequate and complete application or are the result of subsequent coordination between NMFS and Transco. Transco has agreed that all of the monitoring and reporting measures are appropriate. NMFS describes those below as requirements, and has included them in the issued IHA.
Visual Monitoring
Marine mammal monitoring during pile driving activities must be conducted by NMFS-approved PSOs in a manner consistent with the following:
PSOs must be independent of the activity contractor (for example, employed by a subcontractor), 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 for experience performing the duties of a PSO during construction activities pursuant to NMFS-issued take authorization;
Where a team of three or more PSOs is required, a lead observer or monitoring coordinator will be designated. The lead observer will be required to have prior experience working as a marine mammal observer during construction activity pursuant to a NMFS-issued incidental take authorization; and,
PSOs must be approved by NMFS prior to beginning any activity subject to this IHA.
PSOs should also have the following qualifications:
Ability to conduct field observations and collect data according to assigned protocols;
Experience or training in the field identification of marine mammals, including identification of behaviors;
Sufficient training, orientation, or experience with the construction
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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,
Ability to communicate orally, by radio or in person, with project personnel to provide real-time information on marine mammals observed in the area as necessary.
Visual monitoring would be conducted by trained PSOs positioned at suitable vantage points to generally be able to observe the entirety of the shutdown zones. Transco would place at least two PSOs at each active pile driving site during all pile driving and removal activities. During concurrent pile driving activities, this would translate to at least four PSOs being placed within a given location to conduct monitoring: at least one PSO would monitor each shutdown zone around each active hammer. An additional PSO would be placed at each site to monitor the extents of each shutdown zone and beyond. PSOs would be stationed either on the construction barge or a separate support vessel. PSOs would monitor for marine mammals 360 degrees around their respective vessels.
Monitoring would be conducted 30 minutes before, during, and 30 minutes after all in water construction activities. In addition, PSOs will record all incidents of marine mammal occurrence, regardless of distance from activity, and will document any behavioral reactions in concert with distance from piles being driven or removed. Pile driving activities include the time to install or remove a single pile or series of piles, as long as the time elapsed between uses of the pile driving equipment is no more than 30 minutes.
North Atlantic Right Whale and Other Marine Mammal Awareness
Throughout each day, Transco plans to use available sources of information on North Atlantic right whale and other marine mammals, including but not limited to Whale Alert, Whale Map, RWSAS, and U.S. Coast Guard very high frequency (VHF) Channel 16, to receive notifications of any marine mammal sightings and information associated with any DMAs. Maintaining frequent daily awareness of North Atlantic right whale presence in the area, through Transco's ongoing visual monitoring efforts and opportunistic data sources (outside of Transco's efforts), and subsequent coordination for disseminating that information across project personnel affords increased protection of North Atlantic right whales and other marine mammals by alerting project personnel and the marine mammal monitoring team to a higher likelihood of encountering these species, potentially increasing the efficacy of mitigation efforts.
Reporting
Transco would submit a draft marine mammal monitoring report to NMFS within 90 days after the completion of pile driving activities, or 60 days prior to a requested date of issuance of any future IHAs for the project, or other projects at the same location, whichever comes first. The marine mammal monitoring report will include an overall description of work completed, a narrative regarding marine mammal sightings, and associated PSO data sheets. Specifically, the report will include:
Dates and times (begin and end) of all marine mammal monitoring;
Construction activities occurring during each daily observation period, including: (1) the number and type of piles that were driven and the method (
e.g.,
impact or vibratory); and (2) total duration of driving time for each pile (vibratory driving) and 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 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: (1) name of PSO who sighted the animal(s) and PSO location and activity at time of sighting; (2) time of sighting; (3) 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; (4) distance and location of each observed marine mammal relative to the pile being driven for each sighting; (5) estimated number of animals (min/max/best estimate); (6) estimated number of animals by cohort (adults, juveniles, neonates, group composition,
etc.
); (7) animal's closest point of approach and estimated time spent within the harassment zone; (8) 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); (9) Description of any actions implemented in response to the sighting (
e.g.,
delays, shutdown) and time and location of the action;
Number of marine mammals detected within the harassment zones, by species; and,
Summary information about implementation of any mitigation (
e.g.,
shutdowns and delays), a description of specific actions that ensued, and resulting changes in behavior of the animal(s), if any.
A final report must be prepared and submitted within 30 calendar days following receipt of any NMFS comments on the draft report. If no comments are received from NMFS within 30 calendar days of receipt of the draft report, the report shall be considered final. All PSO data would be submitted electronically in a format that can be queried such as a spreadsheet or database and would be submitted with the draft marine mammal report.
In the event that personnel involved in the construction activities discover an injured or dead marine mammal, the Transco must report the incident to the NMFS Office of Protected Resources (OPR) (
PR.ITP.MonitoringReports@noaa.gov
and
itp.fleming@noaa.gov
) and Greater Atlantic Regional Fisheries Office (GARFO) Northeast Marine Mammal and Sea Turtle Entanglement Hotline (866-755-6622) as soon as feasible. If the death or injury was clearly caused by the specified activity, the Transco must immediately cease the activities until NMFS OPR 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 this IHA. Transco 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 animals(s), if alive;
If available, photographs or video footage of the animal(s); and,
printed page 45748)
General circumstances under which the animal was discovered.
North Atlantic Right Whale Reporting
Transco will also report any sightings of North Atlantic right whales by PSOs or project personnel to NMFS (866-755-6622), and the Right Whale Sightings Advisory System (RWSAS) or through the WhaleAlert app. The report must include the time, date, and location of the sighting, number of whales, animal description/certainty of sighting (provide photos/video if taken), PSO/personnel name, and reporter's contact information.
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 impacts or responses (
e.g.,
intensity, duration), the context of any impacts or responses (
e.g.,
critical reproductive time or location, foraging impacts affecting energetics), 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' 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 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).
To avoid repetition, the majority of our analysis applies to all the species listed in table 1, given that many of the anticipated effects of this project on different marine mammal stocks are expected to be relatively similar in nature. Where there are meaningful differences between species or stocks, or groups of species, in anticipated individual responses to activities, impact of expected take on the population due to differences in population status, or impacts on habitat, they are described independently in the analysis below.
Pile driving and removal associated with this project, as outlined previously, have the potential to disturb or displace marine mammals. Specifically, the specified activities may result in take, in the form of Level B harassment and, for some species, Level A harassment from underwater sounds generated by pile driving and removal. Potential takes could occur if individuals are present in the ensonified zone when these activities are underway.
No serious injury or mortality is expected, even in the absence of required mitigation measures, given the nature of the activities. Further, for eight species of marine mammals, no take by Level A harassment is anticipated, due to the rarity of the species near the project area. The likelihood of take by Level A harassment occurring is further reduced implementation of mitigation measures such as shutdown zones that encompass all or a portion of the Level A harassment zones (see Mitigation section).
Level A harassment is authorized for humpback whale, minke whale, bottlenose dolphin, harbor porpoise, and pinnipeds that may occur in the project area (gray seal, harbor seal, and harp seal). Any take by Level A harassment is expected to result in, at most, a small degree of AUD INJ (
i.e.,
minor degradation of hearing capabilities within regions of hearing that align most completely with the energy produced by impact pile driving such as the low-frequency region below 2 kHz), not severe hearing impairment or impairment within the ranges of greatest hearing sensitivity. Animals would need to be exposed to higher levels and/or longer duration than are expected to occur here in order to incur any more than a small degree of PTS.
Additionally, the number of takes by Level A harassment authorized is very low. NMFS expects no more than 4 takes by Level A harassment for humpback whale; 1 take by Level A harassment for minke whale; and 11 takes by Level A harassment for harbor porpoise. The authorized number of takes by Level A harassment for bottlenose dolphin and the guild of pinnipeds that may occur in the project area are a bit larger—42 takes and 44 takes, respectively. However, for all hearing groups, if hearing impairment occurs, it is most likely that the affected animal would lose only a few dB in its hearing sensitivity. Due to the small degree anticipated, any AUD INJ potentially incurred would not be expected to affect the reproductive success or survival of any individuals, much less result in adverse impacts on the species or stock.
Additionally, some subset of the individuals that are behaviorally harassed could also simultaneously incur some small degree of TTS for a short duration of time. However, since the hearing sensitivity of individuals that incur TTS is expected to recover completely within minutes to hours, it is unlikely that the brief hearing impairment would affect the individual's long-term ability to forage and communicate with conspecifics, and would therefore not likely impact reproduction or survival of any individual marine mammal, let alone adversely affect rates of recruitment or survival of the species or stock.
Effects on individuals that are taken by Level B harassment in the form of behavioral disruption, on the basis of reports in the literature as well as monitoring from other similar activities, would likely be limited to reactions such as avoidance, increased swimming speeds, increased surfacing time, or decreased foraging (if such activity were occurring) (
e.g.,
Thorson and Reyff, 2006). Most likely, individuals would simply move away from the sound source and temporarily avoid the area where pile driving is occurring. If sound produced by project activities is sufficiently disturbing, animals are likely to simply avoid the area while the activities are occurring. We expect that any avoidance of the project areas by marine mammals would be temporary in nature and that any marine mammals that avoid the project areas during construction would not be permanently displaced. Short-term avoidance of the project areas and energetic impacts of interrupted foraging or other important behaviors is unlikely to affect the reproduction or survival of individual marine mammals, and the effects of behavioral disturbance on individuals is not likely to accrue in a manner that would affect the rates of recruitment or survival of any affected stock.
Some individual marine mammals in the project area, such as harbor seals or bottlenose dolphins, may be present and be subject to repeated exposure to sound from pile driving activities on multiple days. However, pile driving and extraction is not expected to occur on every day, and these individuals would likely return to normal behavior during gaps in pile driving activity within each day of construction and in between work days. As discussed above, individuals could temporarily relocate
printed page 45749)
during construction activities to reduce exposure to elevated sound levels from the project. Thus, even repeated Level B harassment of some small subset of an overall stock is unlikely to result in any effects on rates of reproduction and survival of the stock.
The project is also not expected to have significant adverse effects on affected marine mammals' habitats. The project activities would not modify existing marine mammal habitat for a significant amount of time. The activities may cause a low level of turbidity in the water column and some fish may leave the area of disturbance, thus temporarily impacting marine mammals' foraging opportunities in a limited portion of the foraging range; but, because of the short duration of the activities and the relatively small area of the habitat that may be affected (with the exception of right whales, there are no habitats of known particular importance to marine mammals), the impacts to marine mammal habitat are not expected to cause significant or long-term negative consequences.
There is a BIA for migrating right whales that intersects with the offshore portion of the project area (LaBrecque
et al.,
2015; Van Parijs
et al.,
2015), but it is active between March and April and November and December, when most of the project activities are not planned to occur. This suggests that impacts from the project would have minimal to no impact on important right whale habitat and would therefore not affect reproduction and survival. While there are plans for project activities to occur in November, and Transco has also accounted for the potential that the project schedule could shift into any time of year, most of the North Atlantic right whales observed in the New York Bight, when present, are detected in deeper waters of the continental shelf, much further offshore (Zoidis
et al.,
2021; Morrison and Taggart, 2021, accessed July 25, 2025). Given the nature of migratory behavior (
e.g.,
continuous path), as well as the low number of total takes, we anticipate that few, if any, of the instances of take would represent repeat takes of any individual.
As described above, North Atlantic right, humpback, and minke whales are experiencing ongoing UMEs, and an ongoing UME for gray and harbor seals is pending closure. However, we do not expect authorized takes to exacerbate or compound upon these ongoing and closure pending UMEs. As discussed above, very little injury is expected or authorized, and the impact of Level A and Level B harassment takes of these species will be minimized through the implementation of mitigation measures. The UMEs do not provide cause for concern regarding population-level impacts. Moreover, no serious injury or mortality is expected or authorized. Despite the UMEs, the relevant population of humpback whales (the West Indies breeding population, or DPS), minke whales, and relevant pinniped species (gray and harbor seals) remain healthy.
For North Atlantic right whales, no injury as a result of the project is expected or authorized, and Level B harassment takes of right whales are expected to be in the form of avoidance of the immediate area of construction. In addition, the number of authorized takes by level B harassment are minimal (
i.e.,
12). As no injury or mortality is expected or authorized, the authorized takes of right whales would not exacerbate or compound the ongoing UME in any way.
Finally, it is unlikely that minor noise effects in a small, localized area of habitat would have any effect on the reproduction or survival of any individuals, much less these stocks' annual rates of recruitment or survival. 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 would have only minor, short-term effects on individuals. The specified activities are not expected to impact rates of recruitment or survival and would therefore not result in population-level impacts.
In summary and as described above, the following factors primarily support our determination that the impacts resulting from this activity are not expected to adversely affect any of the species or stocks through effects on annual rates of recruitment or survival:
No serious injury or mortality is anticipated or authorized;
No take by Level A harassment is authorized for seven species;
Take by Level A harassment would be of low severity;
Takes by Level B harassment would primarily be in the form of behavioral disturbance, resulting in avoidance of the project areas around where impact or vibratory pile driving is occurring, with some low-level TTS that may limit the detection of acoustic cues for relatively brief amounts of time in relatively confined footprints on their populations;
The lack of anticipated significant or long-term negative effects to marine mammal habitat;
Effects on species that serve as prey for marine mammals from the specified activities are expected to be short-term and, therefore, any associated impacts on marine mammal feeding are not expected to result in significant or long-term consequences for individuals, or to accrue to adverse impacts on their populations from either project;
The ensonified areas are small relative to the overall habitat ranges of all species and stocks, and overlap with known areas of important habitat is minimal;
Transco is required to implement mitigation measures, including visual monitoring and shutdown zones, to minimize the numbers of marine mammals exposed to injurious levels of sound.
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 planned monitoring and mitigation measures, NMFS finds that the total marine mammal take from the activity will have a negligible impact on all affected marine mammal species or stocks.
Small Numbers
As noted previously, only take of small numbers of marine mammals may be authorized under section 101(a)(5)(A) and (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 (see
86 FR 5322
, January 19, 2021). Additionally, other qualitative factors may be considered in the analysis, such as the temporal or spatial scale of the activities.
For all stocks, except for the Western North Atlantic Migratory Coastal stock of bottlenose dolphin, the authorized number of takes is less than one-third of the best available population abundance estimate (
i.e.,
less than 1 percent for 11 stocks, less than 4 percent for 2 stocks, and less than 18 percent for 2 stocks) (table 11).
The total number of authorized takes for bottlenose dolphins, if assumed to accrue solely to new individuals of the northern migratory coastal stock, is 35 percent of the total stock abundance, which is currently estimated as 6,639.
printed page 45750)
However, these numbers represent the estimated incidents of take, not the number of individuals taken. That is, it is highly likely that a relatively small subset of these bottlenose dolphins, given their range extends well beyond the project area, will be harassed by project activities.
Given that the specified activity will be stationary within an area not recognized as being of any special significance that would serve to attract or aggregate dolphins, we therefore conclude that the estimated numbers of takes, were they to occur, likely represent repeated exposures of a much smaller number of bottlenose dolphins and that these estimated incidents of take represent small numbers of bottlenose dolphins.
Based on the analysis contained herein of the activity (including the mitigation and monitoring measures) and the estimated take of marine mammals, NMFS finds that small numbers of marine mammals would 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 of 1973 (
16 U.S.C. 1531
et seq.
) requires that each Federal agency ensures 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 OPR consults internally whenever we propose to authorize take for endangered or threatened species, in this case with NMFS' GARFO. NMFS OPR is authorizing take of North Atlantic right whale, fin whale, and sei whale, which are listed under the ESA.
In 2020, NMFS GARFO concluded consultation pursuant to section 7 of the ESA with the Federal Energy Regulatory Commission regarding Transco's proposed Northeast Supply Enhancement Project. That consultation considered effects of all proposed Federal actions, inclusive of the proposed issuance of an IHA to Transco. GARFO concluded that no take, as defined by the ESA, was anticipated to occur and that NMFS OPR's action was not likely to adversely affect any ESA-listed marine mammal species.
NMFS OPR requested initiation of section 7 consultation with NMFS GARFO for the issuance of this IHA. Upon consideration of that request, NMFS GARFO determined that the conclusions reached in the 2020 consultation remain valid and no additional consultation is necessary for the current action. Therefore, NMFS has determined that the 2020 consultation sufficiently analyzed the effects of the issuance of an IHA to Transco.
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 NAO 216-6A, which do not individually or cumulatively have the potential for significant impacts on the quality of the human environment and for which we have not identified any extraordinary circumstances that would preclude this categorical exclusion. Accordingly, NMFS has determined that the issuance of the IHA qualifies to be categorically excluded from further NEPA review.
Authorization
NMFS has issued an IHA to Transco for the potential harassment of small numbers of 15 marine mammal species (16 stocks) incidental to the Northeast Supply Enhancement Project in Raritan Bay, Lower New York Bay, and the Atlantic Ocean that includes the previously explained mitigation, monitoring, and reporting requirements.
Dated: September 19, 2025.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries Service.
FR Doc. 2025-18424
Filed 9-22-25; 8:45 am]
BILLING CODE 3510-22-P
Published Document: 2025-18424 (90 FR 45730)
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