Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Geophysical Surveys in the Gulf of America

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

An incidental take authorization shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring, and reporting of such takings are set forth.

NMFS has defined “negligible impact” in 50 CFR 216.103 as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival. The MMPA states that the term “take” means to harass, hunt, capture, kill or attempt to harass, hunt, capture, or kill any marine mammal.

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

On January 19, 2021, we issued a final rule with ITRs to govern the unintentional taking of marine mammals incidental to geophysical survey activities conducted in U.S. waters of the GOA over the course of the statutory maximum of 5 years (86 FR 5322, January 19, 2021). NMFS subsequently discovered that the 2021 rule was based on erroneous take estimates. We conducted another rulemaking to reassess the statutorily required findings for issuance of the 2021 ITRs using correct take estimates and other newly available and pertinent information relevant to the analyses supporting some of the findings in the 2021 final rule and the taking allowable under the regulations. We issued a final rule affirming those findings in April 2024 (89 FR 31488, April 24, 2024). The 2024 rule did not result in any changes to the existing ITRs, which provide a framework for authorization of incidental take through LOAs upon request from individual applicants planning specific geophysical survey activities. The existing ITRs are in effect through April 19, 2026.

On March 25, 2025, NMFS received an application from EnerGeo requesting development of ITRs governing the taking of marine mammals incidental to geophysical survey activity conducted in the GOA over the course of 5 years following the date of issuance. Following receipt of NMFS' comments on the draft application on April 15, 2025, EnerGeo submitted revised versions of the application on July 14, August 8, and August 12, 2025. On September 24, 2025 (90 FR 45936), we published a notice of receipt of the request in the Federal Register, requesting comments and information related to the request.

On August 28, 2025, NMFS OPR received a request from NMFS Policy for reimplementation of the current ITRs. The request notes that the pending April 2026 expiration of the current ITRs would affect regulatory certainty with loss of an efficient permitting framework, and that reimplementation of the existing ITRs on the basis of the same specified activity and activity levels defined in the initial 2021 final rule and associated estimates of incidental take evaluated in the 2024 corrective rulemaking is consistent with the MMPA and appropriate pursuant to Executive Orders 14156, “Declaring a National Energy Emergency,” and 14154, “Unleashing American Energy.” On September 3, 2025 (90 FR 42569), we published a notice of receipt of the request in the Federal Register, requesting comments and information related to the request. All comments received are available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-america. Among the comments was a letter from EnerGeo and other industry trade associations expressing support for NMFS' proposed issuance of reimplemented ITRs until superseded by new ITRs promulgated on the basis of the separate EnerGeo request. Please see the letters for full comments.

On October 20, 2025, BOEM (the original petitioner for the current ITRs) submitted a request to be included in the process as a co- petitioner, expressing support for the requested reimplementation of the existing ITRs. Both the NMFS Policy and BOEM requests are available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-america.

This final rule provides analysis of the same activities and activity levels considered for the 2021 final rule, which were unchanged in the 2024 final rule, and utilizes the same modeling methodology described in the 2024 final rule. We incorporate the best available information, including information that was newly evaluated in the 2024 final rule and any information that is newly available since issuance of the 2024

final rule. The 2024 final rule incorporated expanded modeling results relative to the 2021 final rule that estimate take utilizing the existing methodology but also consider the effects of using smaller airgun arrays (relative to the proxy source originally defined by BOEM) that are currently prevalent as evidenced by LOA applications received by NMFS to date (see https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-america).

There are no changes to the nature or level of the specified activities within or across years or to the geographic scope of the activity. There is no new information pertaining to the estimates of marine mammal take presented in the 2024 final rule and, therefore, no changes to those take numbers. Based on our assessment of the specified activity in light of the 2024 revised take estimates and other new information, we have determined that the proposed ITRs, which reimplements the current ITRs and includes the required mitigation and associated monitoring measures, satisfies the MMPA requirement to prescribe the means of effecting the LPAI on the affected species or stocks and their habitat, and contains the requirements pertaining to monitoring and reporting.

The specified activity for this action as requested by the NMFS' Policy petition is unchanged from the specified activity considered for the 2021 and 2024 rules, consisting of geophysical surveys conducted for a variety of reasons. Actual total amounts of effort (including by survey type and location) are not known in advance of receiving LOA requests, but take in excess of what is analyzed in this rule would not be authorized. Applicants seeking authorization for take of marine mammals incidental to survey activities outside the geographic scope of the rule (i.e., within the former Gulf of Mexico Energy Security Act (GOMESA) (Sec. 104, Pub. L. 109-432) \3\ moratorium area) would need to pursue a separate MMPA incidental take authorization (see figure 1).

\3\ The Congressional moratorium in GOMESA was in place until June 30, 2022. On September 8, 2020, the President withdrew, under section 12 of the Outer Continental Shelf Lands Act, the same area covered by the prior GOMESA moratorium from disposition by leasing for 10 years, beginning on July 1, 2022, and ending on June 30, 2032.

EnerGeo's 2025 ITR petition suggests that the existing level of effort estimates, by survey type and location, are a reasonable representation of the activities expected to occur under our final ITR reimplementation rule (which EnerGeo supports). EnerGeo's petition, available online at: https://www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-america, carries forward the same survey types and similar estimated annual levels of effort by survey type and location as specified by BOEM over a 10-year period (as adjusted in 2020 by BOEM to account for removal from consideration of the area then under a Congressional leasing moratorium under GOMESA). The most notable difference is EnerGeo's estimate that approximately 40 percent of forecast survey effort may be accomplished using alternative sources that have less environmental impact than airgun arrays (e.g., tuned pulse or dual barbell sources; additional descriptions of these source types may be found in Federal Register notices of LOA issuance under the existing ITRs, e.g., 86 FR 37309, July 15, 2021; 87 FR 55790, September 12, 2022; 88 FR 72739, October 23, 2023). NMFS will address these changes to survey effort in a future rulemaking on EnerGeo's petition. For the current rulemaking, we have determined the specified activity that is the subject of this final rule is a reasonable projection on which to proceed.

Geophysical surveys are conducted to obtain information on marine seabed and subsurface geology for a variety of reasons, including to obtain data for hydrocarbon and mineral exploration and production; aid in siting of oil and gas structures, facilities, and pipelines; identify possible seafloor or shallow depth geologic hazards; and locate potential archaeological resources and benthic habitats that should be avoided.

Deep penetration seismic surveys using airgun arrays as an acoustic source (sound sources are described in the Detailed Description of Activities section) are a primary method of obtaining geophysical data used to characterize subsurface structure. These surveys are designed to illuminate deeper subsurface structures and formations. A deep penetration survey uses an acoustic source suited to provide data on geological formations that may be thousands of meters (m) beneath the seafloor, as compared with a shallow penetration or high resolution geophysical (HRG) survey that may be intended to evaluate shallow subsurface formations or the seafloor itself (e.g., for hazards).

Deep penetration surveys may be two-dimensional (2D) or three- dimensional (3D), and there are a variety of survey methodologies designed to provide the specific data of interest. 2D surveys are designed to acquire data over large areas (thousands of square miles) in order to screen for potential hydrocarbon prospectivity, and provide a cross-sectional image of the structure. In contrast, 3D surveys may use similar acoustic sources but are designed to cover smaller areas with greater resolution (e.g., with closer survey line spacing), providing a volumetric image of underlying geological structures. Repeated 3D surveys are referred to as four-dimensional (4D), or time- lapse, surveys that assess the depletion of a reservoir.

Shallow penetration and high-resolution surveys are designed to highlight seabed and near-surface potential obstructions, archaeology, and geohazards that may have safety implications during rig installation or well and development facility siting. Shallow penetration surveys may use a small airgun array, single airgun, or similar sources, while high-resolution surveys (which are limited to imaging the seafloor itself) may use a variety of sources, such as sub- bottom profilers, single or multibeam echosounders, or side-scan sonars.

Because the specifics of acoustic sources to be used cannot be known in advance of receiving LOA requests from industry operators, it is necessary to define representative acoustic source parameters, as well as representative survey patterns. The supporting modeling for the 2021 ITRs considered two specific airgun array sizes/configurations (4,130 and 8,000 in\3\ arrays) as well as a single, 90-in\3\ airgun. For the 2024 rule, modeling of a third representative airgun array size (5,110-in\3\) was also specifically considered. In its petition for the 2021 ITRs, BOEM determined realistic representative proxy sound sources and survey patterns. We note that EnerGeo's 2025 petition for new ITRs carries forward these assumed proxies regarding survey patterns, as well as the 5,110-in\3\ array modeled for the 2024 rule, as representative of ongoing industry survey activities in the GOA.

Acoustic exposure modeling for the 8,000-in\3\ airgun array and 90- in\3\ single airgun, which provided support for the 2021 rule, was described in detail in “Acoustic Propagation and Marine Mammal Exposure Modeling of Geological and Geophysical Sources in the Gulf of Mexico” and “Addendum to Acoustic Propagation and Marine Mammal Exposure Modeling of Geological and Geophysical Sources in the Gulf of Mexico” (Zeddies et al., 2015, 2017a). Additional information, including evaluation of the 4,130-in\3\ airgun array, was provided in “Gulf of Mexico Acoustic Exposure Model Variable Analysis” (Zeddies et al., 2017b).

Modeling of the more representative 5,110-in\3\ airgun array for NMFS' 2024 rule (in view of LOA applications received to date under the current ITRs) was described in a 2022 memorandum (Weirathmueller et al., 2022). These reports provide full detail regarding the modeled acoustic sources and survey types and are available online at: www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-america.

Representative sources for the modeling include the three different airgun arrays, the single airgun, and an acoustic source package including a sub-bottom profiler in combination with multibeam echosounder and side-scan sonar. Two major survey types were considered: large-area seismic (including 2D, 3D NAZ, 3D WAZ, and coil surveys) and small-area, high-resolution geotechnical (including single airgun surveys and HRG surveys using the aforementioned package of sources). The nominal airgun sources used for analysis of this final rule include a small single airgun (90-in\3\

airgun) and a large airgun array (8,000-in\3\). While the 5,110-in\3\ airgun array is considered most representative of the airgun sources that are likely to be used during deep penetration surveys during the period of effectiveness of these ITRs, the 8,000-in\3\ airgun array results in larger take numbers for most species for which acoustic exposures were modeled, and provides the basis for the analysis herein to allow the flexibility for applicants to use larger sources when survey objectives dictate. The modeling for the alternative 4,130- and 5,110-in\3\ arrays provides more realistic estimates of take for use in survey-specific LOAs, depending on the actual acoustic sources planned for use (see Letters of Authorization section). We note that while high-resolution geophysical sources were included for consideration in the 2021 final rule to allow for take authorization if necessary, these types of sources would not typically be expected to cause the incidental take of marine mammals (Ruppel et al., 2022).

New technologies and/or uses of existing technologies may come into practice during the period of validity of these regulations. As under the 2021 and 2024 final rules, NMFS will evaluate any such developments on a case-specific basis to determine whether expected impacts on marine mammals are consistent with those described or referenced in this document and, therefore, whether any anticipated take incidental to use of those new technologies or practices may appropriately be authorized under the existing regulatory framework. See Letters of Authorization for additional information.