Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar in the Western and Central North Pacific Ocean and Eastern Indian Ocean

The Navy must use a comprehensive three-part monitoring program to support the implementation of real-time, activity-based mitigation measures described in the next section. The combined use of all three types of monitoring (i.e., visual monitoring, passive acoustic monitoring, and active acoustic monitoring) increases the likelihood of marine mammal detection and, thereby, the effectiveness of the mitigation measures. The mitigation monitoring measures are provided in table 6.

Table 6--Mitigation Monitoring

Monitoring method Requirements

Visual Monitoring Visual observations must be conducted by

trained Lookouts on the vessel's bridge

using standard binoculars (7x) and the

naked eye. Pedestal-mounted `Big Eye'

(20 x 110 millimeter (mm)) binoculars

(if installed) must be used to assist in

the detection of marine mammals in the

vicinity of the vessel.

Lookouts must conduct visual monitoring

from the vessel's bridge during all

daylight hours (30 minutes before

sunrise until 30 minutes after sunset).

During training and testing activities

that employ SURTASS LFA sonar in the

active mode, Lookouts must conduct

visual monitoring beginning 30 minutes

before sunrise or 30 minutes before

SURTASS LFA sonar begins to transmit and

continue until 30 minutes after sunset

or until 15 minutes after the SURTASS

LFA sonar transmissions cease.

Lookouts must log all detections of

marine mammals during SURTASS LFA sonar

transmissions.

Lookouts must record the number,

identification, bearing, and range of

observed marine mammals and must

identify marine mammals to the lowest

taxonomic level possible.

Lookouts must continue visual

observations until 15 minutes have

passed since the last detection of the

marine mammal. Passive Acoustic Monitoring.. Navy passive acoustic sonar technicians

must conduct passive acoustic monitoring

using the SURTASS towed horizontal line

array to detect vocalizing marine

mammals. Passive acoustic sonar

technicians are trained to identify

detected vocalizations to marine mammal

species whenever possible.

Passive acoustic monitoring must begin 30

minutes before the SURTASS LFA sonar

begins to transmit and continue until 15

minutes after SURTASS LFA sonar

transmissions cease.

If a detected sound is estimated to be

from a vocalizing marine mammal, the

sonar technician will notify the senior

military member-in-charge, who must

alert the HF/M3 sonar operator and

Lookouts (during daylight). Active Acoustic (HF/M3) Active acoustic mitigation uses the HF/M3

Monitoring sonar to detect, locate, and track

marine mammals in relation to the

SURTASS LFA sonar array and the LFA

mitigation zone.

HF/M3 sonar monitoring must begin 30

minutes before the SURTASS LFA sonar

begins to transmit and continue until 15

minutes after SURTASS LFA sonar

transmissions cease.

If a marine mammal is detected during HF/

M3 monitoring within the SURTASS LFA

mitigation zone, the sonar operator must

notify the senior military member-in-

charge.

Note: Effectiveness of the HF/M3 sonar system as a mitigation tool to

detect marine mammals has been described in the Navy's 2001 Final

Overseas Environmental Impact Statement/Environmental Impact Statement

(OEIS/EIS) (section 2 and section 4) for SURTASS LFA sonar (U.S.

Department of the Navy, 2001) in addition to the technical report by

Ellison and Stein (1999). To summarize the effectiveness of the HF/M3

sonar system, the Navy's testing and analysis of the HF/M3 sonar

system's capabilities indicated the system: (1) substantially

increased probability of detecting marine mammals within the LFA

mitigation zone; (2) provided a superior mitigation capability,

especially for medium- to large-sized marine mammals to a distance of

2-2.5 km from the system; (3) would result in detections of a marine

mammal before it even entered the LFA mitigation zone--based on the

scan rate of the HF/M3 sonar system, most animals would receive at

least eight pings from the sonar (i.e., eight sonar returns or

detections) before entering the LFA mitigation zone; (4) based on scan

rate, probability of any marine mammal being detected prior to

entering the LFA mitigation zone approached 100 percent (Ellison and

Stein, 1999); (5) the probability of HF/M3 sonar system detecting a

medium- to large-sized (approximately 10-30 m) marine mammal (humpback

to blue whale) swimming towards the system in the LFA mitigation zone

with only one HF/M3 ping would be near 100 percent (Ellison and Stein,

1999); (6) for small (approximately 2.5 m) marine mammals such as a

dolphin, detection probability is 55 percent from one HF/M3 ping when

the sonar is located at a distance of 800-930 m from the marine

mammal, while detection probability increased to 90 percent for four

HF/M3 pings; and (7) may result in higher detection probabilities in a

typical at-sea operating environment--during HF/M3 testing, analysts

noted that in expected at-sea conditions of reduced clutter

interference in the open ocean and small marine mammals traveling in

their typical group configurations (i.e., in pods), the detection rate

would be higher (Ellison and Stein, 1999). Also, we note that the

underwater conditions during which the HF/M3 data on detection

distances were collected were extremely challenging (i.e., poor sea

state and weather conditions).

The primary objective of activity-based mitigation is to reduce overlap of marine mammals with stressors that have the potential to cause mortality/serious injury, Level A harassment (AUD INJ and non- auditory injury), or more severe Level B harassment (including TTS) in real time. The Navy customizes mitigation for each applicable activity category or stressor. Activity-based mitigation generally involves: (1) the use of one or more trained Lookouts to diligently observe for marine mammals within a mitigation zone; (2) requirements for Lookouts to immediately communicate sightings of marine mammals to the appropriate watch station for information dissemination; and (3) requirements for the watch station to implement mitigation (e.g., halt an activity) until certain recommencement conditions have been met.

For SURTASS LFA sonar, the Navy must implement the activity-based mitigation measures described below (manned surface vessel mitigation (table 7), ramp up of HF/M3 sonar (table 8), and the SURTASS LFA mitigation zone and suspension/delay (table 9)), as appropriate, in response to an applicable detection within, or entering into, the relevant mitigation zone.

Table 7--Manned Surface Vessel Mitigation

Mitigation requirements Mitigation benefits

Manned surface vessel mitigation, which applies This mitigation is

to T-AGOS vessels underway, will be implemented intended to minimize

to the maximum extent practical based on the the already low

prevailing circumstances, including likelihood of vessel

consideration of safety of vessels, towing strike of a marine

platforms, and crews, as well as mammal.

maneuverability restrictions. Immediately prior to getting underway and while

underway, the Lookouts will observe for marine

mammals. While underway Navy personnel must

maneuver the manned surface vessels (which may

include reducing speed) to maintain a distance

of at least 457.2 m around observed whales and

182.9 m around all other marine mammals (except

bow- or wake-riding dolphins), providing it is

safe to do so. No further action is necessary

if a dolphin continues to approach the vessel

after it has made one course and/or speed

change.. Pedestal-mounted `Big Eye' (20 x 110 mm)

binoculars (if installed) shall be used to

assist in the detection of marine mammals in

the vicinity of the vessel. If the presence of

marine mammals is detected acoustically,

Lookouts posted on the vessel shall increase

the vigilance of their visual observation. Manned surface vessel mitigation will not be

implemented (1) when dolphins are determined to

be intentionally swimming at the bow, alongside

the vessel or vehicle, or directly behind the

vessel or vehicle (e.g., to bow-ride or wake-

ride), (2) when the vessel's safety is

threatened, or (3) when impractical based on

mission requirements (e.g., restricted ability

to maneuver during towing activities).

Table 8--Ramp-Up of High Frequency Marine Mammal Monitoring (HF/M3)

Sonar

Mitigation requirements Mitigation benefits

Prior to full-power use, Navy personnel must A ramp-up procedure

ramp up the HF/M3 sonar power level beginning for the HF/M3 sonar

at a maximum SL of 180 dB re 1 [mu]Pa at 1 m system is intended to

RMS SPL in 10 dB increments to full operating prevent inadvertent

level (if required) over a period of no less exposures of marine

than 5 minutes. mammals to higher Navy personnel must implement this ramp-up received levels more

procedure at least 30 minutes prior to any likely to result in

SURTASS LFA sonar transmissions and any time AUD INJ or more

after the HF/M3 sonar has been powered down for severe behavioral

more than 2 minutes.. responses if an Navy personnel must not increase the HF/M3 animal were to occur

active sonar system's SPL once a marine mammal in close proximity to

is detected. The ramp-up may recommence once the HF/M3 sonar

marine mammals are no longer detected by all of system when it is

the monitoring methods.. turned on.

Table 9--SURTASS LFA Mitigation Zone and Suspension/Delay

Mitigation requirements Mitigation benefits

The Navy has established a single, fixed This mitigation is

mitigation zone of 1.8 km for use with the designed to reduce

suspension and delay measures described below. exposure of marine

At 1.8 km, modeling shows that the sound field mammals to levels of

would be about 174.75 dB. Utilizing a single, sound that have the

fixed mitigation zone for SURTASS LFA sonar potential to cause

training and testing activities standardizes AUD INJ or more

and thus simplifies mitigation implementation severe behavioral

while continuing to ensure protection of marine impacts.

mammals in real time by limiting the potential

for marine mammals to be exposed to received

levels more likely to result in AUD INJ or more

severe behavioral responses. If a marine mammal is detected during visual or

acoustic monitoring within the LFA mitigation

zone, the sonar operator must notify the senior

military member-in-charge, who must order the

immediate delay or suspension of LFA sonar

transmissions. During the delay/suspension,

active acoustic, visual, and passive acoustic

monitoring for marine mammals would continue.. If visual monitoring detects a marine mammal

outside the LFA mitigation zone, the bridge

officer will notify the senior military member-

in-charge of the estimated range and bearing of

the observed marine mammal. For possible visual

or acoustic marine mammal observations outside

of the zone, the sonar operator must verify (in

the case of a visual observation) or determine

(in the case of an acoustic detection) the

range and projected track of the marine mammal

and notify the senior military member-in-charge

that a detected animal is likely to pass within

the LFA mitigation zone. The senior military

member-in-charge must notify the bridge and

passive sonar operator of the potential

presence of a marine animal projected to enter

the mitigation zone. The senior military member-

in-charge must order the delay or suspension of

LFA sonar transmissions only when the marine

mammal enters the LFA mitigation zone. Navy personnel must not commence or recommence

SURTASS LFA sonar transmissions earlier than 15

minutes after all marine mammals have left the

LFA mitigation zone and there is no further

detection of marine mammals within the LFA

mitigation zone by visual, active acoustic (HF/

M3 sonar), or passive acoustic mitigation.

In addition to activity-based mitigation, the Navy must implement geographic mitigation measures to avoid or minimize potential impacts on marine mammals, including a CSR and activity limitations around OBIAs. A full technical analysis of the geographic mitigation that the Navy considered for marine mammals is provided in section 4.6 and appendix F of the 2026 SURTASS SEIS/OEIS. The Navy took into account public comments received on the 2025 SURTASS Draft SEIS/OEIS, 2019 SURTASS SEIS/OEIS, the best available science, and the practicability of implementing additional mitigation measures and has enhanced its mitigation areas and mitigation measures beyond those that were included in the 2019-2026 regulations to further reduce impacts to marine mammals.

NMFS conducted an independent analysis of the geographic mitigation measures that the Navy proposed, which are described below, with a few modifications resulting from coordination between NMFS and the Navy. NMFS' analysis indicates that the measures in these mitigation areas are both practicable and will reduce the likelihood, magnitude, or severity of adverse impacts to marine mammals or their habitat in the manner described in the Navy's analysis and this rule. NMFS is heavily reliant on the Navy's description of operational practicability, since the Navy is best equipped to describe the degree to which a given mitigation measure affects personnel safety or mission effectiveness, and how practical it is to implement. The Navy considers the required measures in this rule to be practicable, and NMFS concurs. We further discuss the manner in which the geographic mitigations will reduce the likelihood, magnitude, or severity of adverse impacts to marine mammal species or their habitat in the Analysis and Negligible Impact Determination section.

Table 10 details geographic mitigation related to the implementation of a CSR.

Table 10--Coastal Standoff Range

Mitigation requirements Mitigation benefits

The received level of SURTASS LFA sonar Many areas of biological

transmissions will not exceed 180 dB importance to, and with higher

re 1 [mu]Pa RMS SPL within 22 km (12 density of, marine mammals

nmi) from any emergent land, including occur in coastal waters. The

offshore islands. CSR would lower the risk to SURTASS LFA sonar activities will not many marine mammals which

occur within the territorial seas of aggregate in coastal waters.

foreign nations, which are areas from In a review of existing and

0 to 22 km (0-12 nmi) from shore.. proposed marine protected

areas, approximately 80

percent were found to be

located in the CSR. Coastal

waters are heavily used

seasonally for biologically

important behaviors such as

calving, foraging, and

migrating.

Given the unique transmission characteristics of SURTASS LFA sonar and recognizing that certain areas of biological importance lie outside of the CSR (i.e., more than 22 km from any emergent land), Navy and NMFS developed the concept of marine mammal OBIAs for SURTASS LFA sonar. OBIAs for SURTASS LFA sonar are not intended to apply to any other Navy activities and were established solely as a mitigation measure to reduce incidental harassment of marine mammals associated with the use of SURTASS LFA sonar (77 FR 50290, August 20, 2012). OBIAs pertain to only species considered more sensitive to SURTASS LFA sonar, including marine mammals in the VLF and LF groups, as well as sperm whales and elephant seals, since the potential for impacts to other protected marine species from exposure to SURTASS LFA sonar transmissions would be low to moderate, necessitating no additional preventative measures for these taxa beyond those already established for SURTASS LFA sonar. Table 11 lists the identified OBIAs (figure 1 herein) within the Study Area, and table 12 describes the mitigation requirements within OBIAs.

Appendix F of the 2026 SURTASS SEIS/OEIS describes the selection criteria and stepwise analysis Navy used to identify OBIAs. In summary, the comprehensive assessment of marine areas as OBIA candidates included a thorough review of the Important Marine Mammal Areas (IMMAs), Ecologically or Biologically Significant Marine Areas (EBSAs), areas listed in the World Database of Protected Areas (WDPA), Mission Blue Hope Spots, Pew Bertarelli Ocean Legacy Sites, High Seas Alliance Hot Spots, NOAA NMSs, NMFS ESA Critical Habitat, and areas previously included on the OBIA Watch List or that otherwise previously received full assessment for potential OBIA designation. The OBIA Watch List includes potential marine areas already identified and reviewed by the Navy and NMFS but for which documentation on the importance of the area to marine mammals has not been established or is lacking in detail. A total of 418 candidate marine areas in the Pacific and Indian Oceans were identified and added to a database for recordkeeping and analysis.

While the BIAs identified by Kratofil et al. (2023) and discussed in the Biologically Important Areas section of this rule were not considered in the OBIA selection criteria, NMFS considered BIAs in this rulemaking. Humpback whale is the only LF cetacean species for which Kratofil et al. (2023) identified a BIA, and this BIA fully overlaps identified OBIAs or the CSR, and therefore, mitigation will be implemented within the BIA. All other BIAs identified in the Pacific SURTASS LFA Study Area fully or partially overlap identified OBIAs or the CSR, as described in the Biologically Important Areas section. NMFS and the Navy also reviewed additional literature that led to the recommended OBIA modifications and addition in this final rule, as described below.

The process for selection of OBIAs for SURTASS LFA sonar, from the candidate list, includes a stepwise analysis based on four criteria: (1) geographic; (2) presence of LF-Hearing cetaceans; (3) biological importance; and (4) Navy practicability: Criterion 1: Geographic

A marine area must be located at least partly in the Study Area and partly outside of the CSR (i.e., the area within 22 km of any emergent land including islands or island systems) for OBIA consideration. The CSR already receives the same protection as OBIAs, and therefore marine areas entirely within the CSR are not considered for further OBIA analysis. Criterion 2: LF-Hearing Cetaceans

A marine area must have evidence of the presence of cetaceans that specialize in LF-hearing, such as all baleen whales, or marine mammals that have demonstrated sensitivity to LF sounds, such as sperm whales and elephant seals. SURTASS LFA sonar transmissions are well below the range of best hearing sensitivity for most other odontocetes and pinnipeds based on the measured hearing thresholds (U.S. Department of the Navy, 2025; Houser et al., 2008; Houser et al., 2024; Kastelein et al., 2009; NMFS, 2024). The intent of OBIAs is to protect those marine mammal species most likely to hear and be affected by SURTASS LFA sonar transmissions and to provide the animal additional protections during periods when they are conducting biologically significant activities. Thus, the primary focus of the OBIA mitigation measures is on LF- hearing sensitive species. Criterion 3: Biological Importance

If a marine area meets Criteria 1 and 2, it must also have known biological importance to the relevant species present. As such, the marine area must meet at least one of the following biological sub- criteria to be considered as an OBIA: (1) have a presence of small, distinct populations with limited distributions; (2) have a presence of particularly high densities; (3) be a known breeding/calving ground(s); (4) be a known foraging ground(s); (5) be a known migration route(s); or (6) be a Critical Habitat as designated under the ESA. When direct data relevant to one of the biological subcriteria are limited, other available data and information may be used if those data and information, either alone or in combination with the limited direct data, are sufficient to establish that the biological criteria are met. Criterion 4: Navy Practicability

If an area meets the (1) geographic, (2) presence of LF-Hearing cetaceans, and (3) biological importance criteria, it is considered a candidate OBIA, and the Navy conducts a practicability assessment (e.g., consideration of personnel safety, practicality of implementation, and impacts on the effectiveness of SURTASS LFA sonar training and testing activities). If the candidate area passes the practicability assessment, then the marine area is considered to meet all criteria for designation as a SURTASS LFA sonar

OBIA for marine mammals. If the Navy determines that it is not practicable to designate the area as an OBIA, the Navy will identify the concerns that lead to this conclusion and discuss with NMFS whether modifications could be made to the proposed OBIA to alleviate the Navy's practicability concerns.

Of the 38 marine areas assessed, the Navy and NMFS' analysis resulted in the recommendation of 5 new OBIAs since publication of the 2019 SURTASS final rule (84 FR 40132, August 13, 2019), pending Navy review for practicability. One OBIA is an expansion of an existing OBIA (OBIA #35, Western Australia--Blue Whale), to include the entirety of the Indian Ocean Blue Whale Migratory Route Important Marine Mammal Area (a designation by the International Union for Conservation of Nature). A second OBIA (OBIA #43, South of Lombok and Sumbawa Islands) represents an area that connects an existing OBIA (OBIA #37, Southern Bali) to the newly expanded OBIA #35, Western Australia-Blue Whale. The remaining three OBIAs are standalone areas (OBIA #40, #41, #42), disconnected from any existing OBIAs in the Study Area.

The five candidate OBIAs underwent Navy practicability review. The Navy determined that the identification of the five candidate OBIAs in the Study Area and the relevant seasonal effectiveness periods would not impede the effectiveness of SURTASS LFA sonar training and testing activities, would be practicable to implement as a geographic mitigation measure, and would not impact personnel safety. As a result, five new marine mammal OBIAs for SURTASS LFA sonar have been identified: OBIA #35 (expansion), #40, #41, #42, and #43 (table 11).

Further, since publication of the proposed rule, NMFS and the Navy identified a new OBIA and modifications to several OBIAs identified in the proposed rule. The new OBIA #44 (Southeast Kamchatka Offshore) will minimize impacts to Western NPRWs in an identified high use foraging area offshore of Southeast Kamchatka. Ovsyanikova et al. (2015) found NPRWs utilize deep, pelagic waters southeast of Kamchatka, an area that could serve as a primary summer foraging grounds and Matsuoka et al. (2021) described two main high-density areas, including one offshore southeast of Kamchatka Peninsula, between latitudes 45 [deg]N and 51 [deg]N, and longitudes 158 [deg]E and 168 [deg]E, which is within the Study Area. Additionally, this final rule includes the following modifications to OBIAs identified in the proposed rule to further minimize adverse impacts to marine mammal populations from SURTASS LFA sonar:

OBIA #28 (Mariana Islands) is now effective from December through May (previously February through April). This extension is supported by information from Oleson et al. (2015), Hill et al. (2016), Hill et al. (2020), and Deakos et al. (2021) showing humpback whales have been regularly sighted in the Mariana Islands from January-March and acoustic detections have been recorded from December-April with the highest level of acoustic activity occurring in January in some areas (Allen et al., 2021);

OBIA #33 (Southeast Kamchatka) is now effective year-round (previously June through September) and has been spatially expanded northward along the eastern side of the Kamchatka Peninsula to meet the northern boundary of the Study Area. The temporal expansion is supported by data from the NMSDD, which included the highest predicted densities of NPRWs in the area of OBIA #33 Southeast Kamchatka (and throughout the entire Study Area) are anticipated in the winter and spring (December-May). The Southeast Kamchatka Coastal Waters Marine EBSA, as determined by the Conference of the Parties to the Convention on Biological Diversity, includes the migratory route for large whales which, in addition to data on NPRW sightings off Cape Kozlova and the western Aleutian Islands (Ovsyanikova et al., 2015), supports the northward expansion of this OBIA; and

OBIA #37 (Southern Bali) is now effective August through November (previously October through November) and has been spatially expanded to minimize impacts to pygmy blue whales participating in reproductive and foraging activities in this area. Sahri et al. (2022) developed a pygmy blue whale habitat suitability model that predicted this area as moderately suitable habitat. Further, a satellite tracking study of pygmy blue whales by M[ouml]ller et al. (2020) confirmed the use of the proposed expanded area south of Bali. In Indonesian waters, whales mostly showed a high probability of being in area restricted search behavior, which is possibly associated with breeding and/or foraging (M[ouml]ller et al., 2020).

Additionally, this final rule corrects errors in the effective period of two OBIAs: OBIA #42 South of Java Island is effective from May through November and OBIA #43 South of Lombok Sumbawa Islands is effective May through November.

Table 11--Identified OBIAs in the Study Area

Relevant marine

OBIA No. Name Location/water body mammal species Effective period

26....................... Main Hawaiian Central North Humpback whale...... November through

Islands. Pacific Ocean. April. 27....................... Northwestern Central North Humpback whale...... December through

Hawaiian Islands. Pacific Ocean. April. 28 **.................... Mariana Islands..... Western North Humpback whale...... December through

Pacific Ocean. May. 29....................... Ryukyu-Philippines.. Western North Humpback whale...... January through

Pacific Ocean. April. 30....................... Ogasawara--Sperm Western North Sperm whale......... June through

whale. Pacific Ocean. September. 31....................... Ogasawara-Kazin-- Western North Humpback whale...... December through

Humpback whale. Pacific Ocean. May. 32....................... Honshu.............. Western North Gray whale.......... January through

Pacific Ocean. May. 33 **.................... Southeast Kamchatka. Western North Fin, gray (Western Year-round.

Pacific Ocean. North Pacific

stock), humpback,

and North Pacific

right whale. 34....................... Gulf of Thailand.... Eastern Indian Ocean Bryde's whale....... April through

November. 35 *..................... Western Australia-- Eastern Indian Ocean Blue (pygmy) whale.. May through

Blue whale. November. 36....................... Western Australia-- Eastern Indian Ocean Humpback whale...... May through

Humpback whale. December. 37 **.................... Southern Bali....... Eastern Indian Ocean Blue (pygmy), August through

Bryde's, humpback, November.

Omura's, sei, and

sperm whale. 38....................... Swatch-of-No-Ground Northern Bay of Bryde's whale....... Year-round.

(SoNG). Bengal. 39....................... Sri Lanka........... Eastern Indian Ocean Blue (pygmy) and October through

sperm whale. April. 40 *..................... Maldives Archipelago Central Indian Ocean Blue (pygmy), October through

Bryde's, humpback, May.

and sperm whale.

41 *..................... Northeast Arabian Arabian Sea......... Blue, Bryde's, and Year-round.

Sea. humpback (Arabian

Sea stock) whale. 42 *..................... South of Java Island East Indian Ocean... Blue (pygmy) whale.. May through

November. 43 *..................... South of Lombok East Indian Ocean... Blue (pygmy) whale.. May through

Sumbawa Islands. November. 44 **.................... Southeast Kamchatka Western North North Pacific right April through

Offshore. Pacific Ocean. whale. October.

Note: This final rule corrects the effective period of OBIA #42 South of Java Island and OBIA #43 South of

Lombok Sumbawa Islands. * New or expanded OBIAs since the 2019 SURTASS final rule (84 FR 40132, August 13, 2019). ** New or expanded OBIA since the proposed rule.

Table 12--OBIA Mitigation Requirements

Mitigation requirements Mitigation benefits

The received level of SURTASS LFA sonar OBIAs would protect species

transmissions will not exceed 180 dB considered more sensitive to

re 1 [mu]Pa RMS SPL at a distance of 1 SURTASS LFA sonar (including

km (0.5 nmi) seaward of the outer marine mammals in the VLF and

perimeter of any OBIA in the SURTASS LF groups, as well as sperm

LFA Study Area during the effective whales and elephant seals)

period \1\ specified. OBIAs and the from receiving injurious

related effective periods are listed effects (i.e., AUD INJ) and

in (table 11) or may be subsequently more severe behavioral impacts

identified through the adaptive from SURTASS LFA

management process.\2\ transmissions. No more than 25 percent of the sound

source amount analyzed (i.e., no more

than 275 hours in a given year) of

SURTASS LFA sonar for training and

testing will be conducted within 18.5

km of any single OBIA during any

year.\3\

\1\ OBIAs are active only during the specific time of year when

biologically significant activities are potentially occurring within

that area. \2\ Although it is difficult to compare SPL and SEL based metrics since

SEL accumulates with increasing exposure time, auditory injury

thresholds are well above 180 dB, even without considering frequency

weighting of the received sound levels, except for VHF cetaceans.

However, VHF cetaceans do not hear well at the low frequencies

associated with SURTASS LFA, so it is expected that the received level

at these frequencies would be greatly reduced. \3\ Should national security present a requirement to conduct more than

25 percent of the analyzed hours of SURTASS LFA sonar within 18.5 km

of any single OBIA during any year, personnel conducting the activity

would be required to obtain approval through the chain of command

prior to commencement of the activity. The Navy must provide NMFS with

notification as soon as is practicable and include the information

(e.g., sonar hours in exceedance of 25 percent) in its annual activity

reports submitted to NMFS.

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NMFS has carefully evaluated the Navy's proposed mitigation measures--many of which were developed with NMFS' input during the previous phases of SURTASS LFA sonar activities--and considered a range of other measures (i.e., the measures considered but eliminated in the 2026 SURTASS SEIS/OEIS, which reflect many of the comments that have arisen from public input or through discussion with NMFS in past years) in the context of ensuring that NMFS prescribes the means of effecting the least practicable adverse impact on the affected marine

mammal species and their habitat. Our evaluation of potential measures included consideration of the following factors in relation to one another: (1) the manner in which, and the degree to which, the successful implementation of the mitigation measures is expected to reduce the likelihood and/or magnitude of adverse impacts to marine mammal species and their habitat; (2) the proven or likely efficacy of the measures; and (3) the practicability of the measures for applicant implementation, including consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity.

Based on our evaluation of the Navy's proposed measures, as well as other measures considered by the Navy and NMFS (see section 4.6 of the 2026 SURTASS SEIS/OEIS), NMFS has determined that these mitigation measures are appropriate means of effecting the least practicable adverse impact on marine mammal species and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and considering specifically personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. Thus, NMFS concludes that the mitigation measures outlined in this final rule satisfy the statutory standard.

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 by Level A harassment or Level B harassment (as presented in table 3), NMFS considers other factors, such as the likely nature of any responses (e.g., intensity, duration) and the context of any responses (e.g., critical reproductive time or location, migration), as well as effects on habitat and the likely effectiveness of the mitigation. We also assess the number, intensity, and context of estimated takes by evaluating this information relative to population status. Consistent with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989), the impacts from other past and ongoing anthropogenic activities are incorporated into this analysis via their impacts on the environmental baseline (e.g., as reflected in the regulatory status of the species, population size and growth rate where known, other ongoing sources of human-caused mortality, and ambient noise levels).

In the Estimated Take of Marine Mammals section, we identified the subset of potential effects that would be expected to qualify as take under the MMPA both annually and over the 7-year period covered by this rule and then identified the maximum number of takes we believe are reasonably expected to occur (harassment) based on the methods described. The impact that any given take will have is dependent on many case-specific factors that need to be considered in the negligible impact analysis (e.g., the context of behavioral exposures such as duration or intensity of a disturbance, the health of impacted animals, the status of a species that incurs fitness-level impacts on individuals). For this rule we evaluated the likely impacts of the enumerated maximum number of harassment takes that are authorized and reasonably expected to occur, in the context of the specific circumstances surrounding these predicted takes. Last, we collectively evaluated this information, as well as mitigation measure effectiveness, that supports our negligible impact conclusions for each stock or species. To avoid repetition, the discussion of our analysis applies to all the species listed in table 1, given that the anticipated effects of this activity on these different marine mammal species or stocks are expected to be similar. There is little information about the nature or severity of the impacts, or the size, status, or structure of any of these species or stocks that would lead to a different analysis for this activity.

The specified activities reflect best estimates of the number of hours the Navy will conduct SURTASS LFA training and testing activities. The Description of the Specified Activity section describes annual activities. There may be some flexibility in the exact number of transmission hours from year to year, but it will not exceed the annual total of 1,100 transmission hours for all vessels and take totals would not exceed the maximum annual total and 7-year total indicated in table 3. We base our analysis and negligible impact determination on the maximum number of takes that would be reasonably expected to occur annually and are authorized, although, as stated before, the number of takes is only one part of the analysis, which includes qualitative consideration of other contextual factors that influence the degree of impact of the takes on the affected individuals.

The Navy's harassment take request was calculated using a model (NAEMO) for acoustic stressors, which NMFS reviewed and concurs does appropriately estimate the maximum amount of harassment that is reasonably likely to occur based on the maximum number of hours and equal distribution of hours across the 15 geographic modeling areas. As described in more detail in the Navy Acoustic Effects Model section of the proposed rule, NAEMO calculates: (1) sound energy propagation from SURTASS LFA sonar during military readiness activities; (2) the sound received by animat dosimeters representing marine mammals distributed in the area around the modeled activity; and (3) whether the sound received by a marine mammal exceeds the thresholds for effects. Assumptions in the Navy models intentionally err on the side of overestimation when there are unknowns. The effects of the specified activities are modeled as though they would occur regardless of proximity to marine mammals, meaning that no activity-based mitigation is considered (e.g., no power down or shut down). However, the modeling does quantitatively consider the possibility that marine mammals would avoid continued or repeated sound exposures to some degree, based on a species' sensitivity to behavioral disturbance. NMFS provided input to, independently reviewed, and concurred with the Navy on this process. The Navy's analysis, which is described in detail in appendix B of the application, was used to quantify harassment takes for this rule.

The Navy and NMFS anticipate more severe effects from takes resulting from exposure to higher received levels and less severe effects from takes resulting from exposure to lower received levels (though this is in no way a strictly linear relationship for behavioral effects throughout species, individuals, or circumstances). However, there is also growing evidence of the importance of distance in predicting marine mammal behavioral response to sound (i.e., sounds of a similar level emanating from a more distant source have been shown to be less likely to elicit a response of equal magnitude) (DeRuiter et al., 2013b). The estimated number of takes by Level A harassment and Level B harassment does not always equate to the number of individual animals the Navy expects to harass (which is lower for some species), but rather represents the instances of take (i.e., exposures above the Level A harassment and Level B harassment threshold) that are anticipated to occur over the 7-year period. These instances may represent either brief exposures (i.e., seconds or minutes) or, in some cases, longer durations of exposure within a day (though no more than 8 hours, which is the maximum amount Navy plans to transmit in 1 day). In some cases, an animal that incurs a single take by AUD INJ or TTS may also experience a direct behavioral harassment from the same exposure. Direct Behavioral Disturbance

The estimates calculated using the BRF do not differentiate between the different types of behavioral responses that qualify as Level B harassment. As described in the application, the Navy identified, with NMFS' input, that moderate behavioral responses, as characterized in Southall et al. (2021), would be considered a take. The behavioral responses predicted by the BRFs are assumed to be moderate severity exposures (e.g., altered migration paths or dive profiles, interrupted nursing, breeding or feeding, or avoidance) that may last for the duration of an exposure. The Navy then compiled the available data indicating received levels and distances at which those responses have occurred and used the indicated literature to build biphasic behavioral response curves and cut-off conditions that are used to predict how many instances of Level B behavioral harassment occur in a day (see the Criteria and Thresholds Technical Report). Take estimates alone do not provide information regarding the potential fitness or other biological consequences of the responses on the affected individuals. We therefore consider the available activity-specific, environmental, and species- specific information to determine the likely nature of the modeled behavioral responses and the potential fitness consequences for affected individuals.

The use of SURTASS LFA sonar in a given region would generally be considered transient and temporary; however, we note the comparatively large ensonified areas generated by the higher-power LF source. In the range of potential behavioral effects that might be expected as part of a response that qualifies as an instance of Level B harassment (which, by nature of the way it is modeled/counted, occurs within 1 day), the less severe end might include exposure to comparatively lower levels of a sound, at a detectably greater distance from the animal, for a few or several minutes to multiple hours within the day of the exposure (though not more than 8 hours, which is the maximum transmission time planned for any single day), which could result in a behavioral response such as avoiding an area that an animal would otherwise have chosen to move through or feed in for some amount of time or breaking off one or a few feeding bouts. More severe effects could occur when the animal is close enough to the SURTASS LFA sonar source to receive a comparatively higher level or is exposed continuously to one source for a longer time. Such effects might result in an animal having a more severe flight response and leaving a larger area for a day or more or potentially losing feeding opportunities for a day. However, such severe behavioral effects are expected to occur infrequently. Of note, monitoring reports indicate that there have been no apparent avoidance responses observed since use of SURTASS LFA sonar training and testing activities began in the Study Area in 2002.

To help assess this, for SURTASS LFA sonar used in the Study Area, the Navy provided information estimating the instances of take by Level B harassment by behavioral disturbance under each BRF that would occur within 6-dB increments, and by distance in 5-km bins in section 2.3.3 of appendix A of the application. As mentioned above, all else being equal, an animal's exposure to a higher received level is more likely to result in a behavioral disturbance that could more likely accumulate to impacts on reproductive success or survivorship of the animal, but other contextual factors (e.g., distance, duration of exposure, and behavioral state of the animals) are also important (Di Clemente et al., 2018; Ellison et al., 2012; Moore and Barlow,

2013; Southall et al., 2019c; Wensveen et al., 2017, etc.). The majority of takes by Level B harassment are expected to be comparatively milder responses (i.e., lower-level exposures that still qualify as take under the MMPA but would likely be less severe along the continuum of responses that qualify as take). We anticipate more severe effects from takes when animals are exposed to higher received levels of sound or at closer proximity to the source, or for longer durations. Specifically, given a range of behavioral responses that may be classified as Level B harassment, to the degree that higher received levels of sound are expected to result in more severe behavioral responses, only a smaller percentage of the anticipated Level B harassment from the specified activities might result in more severe responses. As discussed in the Behavioral Responses section of the proposed rule, behavioral response is likely variable across species (especially considering the reduced sensitivity of HF and VHF species to the SURTASS LFA sonar signal) and individuals within a species and depending on the context of the exposure. Further, the mitigation measures (described in detail in the Mitigation Measures section) are anticipated to reduce the exposure of marine mammals to received levels of SURTASS LFA sonar or HF/M3 sonar that would result in more severe behavioral responses. Diel Cycle

Many animals perform vital functions, such as feeding, resting, traveling, and socializing on a diel cycle (24-hour cycle). Behavioral responses to noise exposure, when taking place in a biologically important context (e.g., disruption of critical life functions, displacement, or avoidance of important habitat) are more likely to be significant if they last more than one diel cycle or recur on subsequent days (Southall et al., 2007). Henderson et al. (2016) found that ongoing smaller scale MFAS events, for example, had little to no impact on foraging dives for Blainville's beaked whale, while multi-day training events may decrease foraging behavior for Blainville's beaked whale (Manzano-Roth et al., 2016). Consequently, a behavioral response lasting less than 1 day and not recurring on subsequent days is not considered severe unless it could directly affect reproduction or survival (Southall et al., 2007). Note that there is a difference between multiple-day substantive behavioral responses and multiple-day anthropogenic activities. SURTASS LFA sonar activities generally cover large areas that are relatively far from shore (typically more than 22 km from shore) and in generally deep waters. Marine mammals are moving as well, which would make it unlikely that the same animal could remain in the immediate vicinity of the ship for the entire duration of the activity. Further, as noted previously, SURTASS LFA sonar is not planned to be used for more than 8 hours in a single day. Assessing the Number of Individuals Taken and the Likelihood of Repeated Takes

As described previously, Navy modeling uses the best available science to predict the instances of exposure above certain acoustic thresholds, which are equated, as appropriate, to harassment takes. As further noted, for active acoustics it is typically challenging to parse out the number of individuals taken by Level B harassment and the number of times those individuals are taken from this larger number of instances, though factors such as movement ecology (e.g., is the species resident and more likely to remain in closer proximity to ongoing activities, versus nomadic or migratory; Keen et al. (2021)) or whether there are known areas where animals are known to congregate and overlap with activities can help inform this. One method that NMFS uses to help better understand the overall scope of the impacts is to compare these total instances of take against the abundance of that species (or stock if applicable). For example, if there are 100 harassment takes in a population of 100, the possibilities include either that every individual was exposed above acoustic thresholds once per year, or that some smaller number were exposed a few times per year while a few were not exposed at all. Where the instances of take exceed 100 percent of the population, multiple takes of some individuals are predicted and expected to occur within a year. Generally speaking, the higher the number of takes as compared to the population abundance, the more multiple takes of individuals are likely, and the higher the actual percentage of individuals in the population that are likely taken at least once in a year. We look at this comparative metric to give us a relative sense of where larger portions of the species are being taken by the Navy's SURTASS LFA sonar activities and where there is a higher likelihood that the same individuals are being taken across multiple days and where that number of days might be higher. It also provides a relative picture of the scale of impacts on each species.

For SURTASS LFA sonar, given the limited maximum annual number of hours of sonar spread across four vessels and a large geographic area, the fact that the training and testing occurs far from shore (>22 km) and outside of known areas of concentration of LFA sonar-sensitive species (OBIAs), and considering the predicted take numbers as compared to known stock abundances (with the exception of beaked whales and the Western North Pacific stock of humpback whales (take as a percentage of stock abundance ranges from 104-207 percent)), it is unlikely that the individuals of most species or stocks are taken on multiple days ( No mortality is anticipated or authorized, nor is any non- auditory injury. Neither stranding nor vessel strikes are expected to result from SURTASS LFA sonar training and testing. There is no empirical evidence of strandings or vessel strikes of marine mammals associated spatially or temporally with the use of SURTASS LFA sonar. Moreover, the sonar system acoustic characteristics differ between LFA sonar and MFA sonars that have been associated with strandings.

The maximum annual allowable instances of take under this rule by Level A harassment (AUD INJ only) range from 0 to 32 (fin whales with NSD).

Regarding authorized takes associated with auditory impairment, as described in the Temporary Threshold Shift (TTS) section, any takes in the form of TTS are expected to be lower-level and of short duration. Any associated lost opportunities or capabilities that individuals might experience as a result of TTS would not be at a level or duration that would be expected to impact reproductive success or survival. For similar reasons, as discussed in the Auditory Injury section, while auditory injury impacts last longer, the low anticipated levels of AUD INJ that could be reasonably expected to result from these activities, should they occur, are unlikely to have any effect on fitness.

The operational characteristics of the specified activities, including the limited maximum annual number of hours of SURTASS LFA sonar (1,100) shared across multiple vessels (likely not in close proximity to one another) and spread over the entire western and central North Pacific Ocean and eastern Indian Ocean (including multiple smaller and separated seas for some species), as well as the 8-hour maximum daily transmission, thus minimize the likelihood of multi-day or long-duration exposures for any individual marine mammals. Further, and as noted above, the context of exposures is important in evaluating the ultimate impacts of Level B harassment on individuals, and in the case of SURTASS LFA sonar, the approaching sound source would be moving through the open ocean at low speeds, so concerns of noise exposure are somewhat lessened in this context compared to situations where animals may not be as able to avoid strong or rapidly approaching sound sources.

Regarding the authorized takes associated with behavioral disturbance, as described in the Potential Effects of Specified Activities on Marine Mammals and Their Habitat section of the proposed rule, behavioral disturbance from SURTASS LFA sonar activities in a given region would generally be considered transient and temporary, though the ensonified area generated by the LF source is comparatively large. Behavioral disturbance is likely variable across species and individuals within a species, and depends on the context of the exposure, and responses are likely to range from less severe (e.g., an animal avoiding an area that it would otherwise have chosen to move through or feed in for some amount of time) to more severe (e.g., an animal having a more severe flight response and leaving a larger area for a day or more). Such severe behavioral effects are expected to occur infrequently due to the implementation of the mitigation measures (e.g., the SURTASS LFA mitigation zone, which is designed to ensure that most marine mammal takes are limited to lower-level Level B harassment, the CSR, and OBIAs).

Previous reports indicate that the HF/M3 active sonar system has proven to be the most effective of the mitigation monitoring measures to detect possible marine mammals in proximity to the transmitting LFA sonar array, and the use of this system substantially increases the probability of detecting marine mammals within the mitigation zone. Because the HF/M3 system is able to monitor marine mammals out to an effective range of 2-2.5 km from the vessel, it is unlikely that the SURTASS LFA sonar operations would expose marine mammals to an SPL greater than about 174 dB re 1 [mu]Pa. Past results of the HF/M3 system tests provide confirmation that the system has a demonstrated probability of single-ping detection of 95 percent or greater for single marine mammals that are 10 m in length or larger, and a probability approaching 100 percent for multiple pings of any sized marine mammal (see chapter 4 of the 2026 SURTASS SEIS/OEIS).

In areas of known or likely biological importance for functions such as feeding or reproduction, effects are mitigated by the CSR and mitigation in the OBIAs for species sensitive to LF sound. The sound field generated by SURTASS LFA sonar will not exceed 180 dB re 1 [mu]Pa RMS SPL within 22 km from any emergent land. Further, no

more than 25 percent (275 hours) of SURTASS LFA sonar will be used for training activities within 18.5 km of any single OBIA during any year. These measures are expected to minimize the likelihood of disruption of marine mammals in areas where important behavior patterns (e.g., migration, calving, breeding, feeding, or sheltering) occur or in areas with small resident populations or higher densities of marine mammals. As a result, any takes that occur are less likely to result in energetic effects or disturbances of other important behaviors that would be more likely to reduce reproductive success or survivorship.

Based on the information in the Marine Mammal Habitat section of the proposed rule, and the supporting information included in the 2026 SURTASS SEIS/OEIS, NMFS has determined that the planned training and testing activities will not have adverse or long-term impacts on marine mammal habitat.

As noted above, there is a higher likelihood that some number of individual beaked whales (of all species and stocks) and humpback whales (Western North Pacific stock) may be taken on up to several days within a year, considering annual take maxima and the total across 7 years. However, as described, given the magnitude and severity of the potential take (especially noting the reduced sensitivity of beaked whales to SURTASS LFA sonar signal), and in consideration of the required mitigation measures and other information presented, the Navy's activities are not expected to result in impacts on the reproduction or survival of any individuals, much less affect annual rates of recruitment or survival at the species or stock level.

The regulations governing the take of marine mammals incidental to military readiness activities in the Study Area contain an adaptive management component (i.e., the authority to modify the LOA's mitigation, monitoring, and reporting measures, consistent with the regulations, based on either the Navy's request or NMFS' initiative in light of new information). In order for NMFS to modify an LOA measure, the modified measure must have the same anticipated effects as the original measure, it must have a reasonable likelihood of effectiveness, NMFS must determine it does not change the findings made for promulgation of the regulations, and the Navy must concur with the measure and affirm that it meets the Navy's practicability standards in the context of personnel safety, practicality of implementation, and impacts on the effectiveness of the Navy's military readiness activity.

The reporting requirements associated with this rule are designed to provide NMFS with monitoring data from the previous year to allow it to consider whether any changes to existing mitigation and monitoring requirements are appropriate. The use of adaptive management allows NMFS to consider new information from different sources to determine (with input from the Navy regarding practicability) on an annual or biennial basis if mitigation or monitoring measures should be modified. Mitigation measures could be modified if new data suggests that such modifications would have a reasonable likelihood of more effectively accomplishing the goals of the mitigation and monitoring and if the measures are practicable. If the modifications to the mitigation, monitoring, or reporting measures are substantial, NMFS would publish a notice in the Federal Register and solicit public comment.

The following are some of the possible sources of applicable data to be considered through the adaptive management process: (1) results from monitoring and exercise reports, as required by MMPA authorizations; (2) compiled results of Navy-funded research and development studies; (3) results from specific stranding investigations; (4) results from general marine mammal and sound research; and (5) any information which reveals that marine mammals may have been taken in a manner, extent, or number not authorized under these regulations and LOA.

Endangered Species Act (ESA)

There are 10 marine mammal species under NMFS jurisdiction that are listed as endangered or threatened under the ESA with confirmed or possible occurrence in the Study Area for which take is authorized: (1) blue whale; (2) fin whale; (3) humpback whale (Western North Pacific DPS); (4) NPRW; (5) sei whale; (6) sperm whale; (7) false killer whale (Main Hawaiian Islands DPS); (8) Hawaiian monk seal; (9) Steller sea lion (Western DPS); and (10) ringed seal (Okhotsk subspecies). The humpback whale (86 FR 21082, April 21, 2021), false killer whale (83 FR 35062, July 24, 2018), and Hawaiian monk seal (51 FR 16047, April 30, 1986; revised in 1988 (53 FR 18988, May 26, 1988) and in 2015 (80 FR 50925, August 21, 2015)) have critical habitat designated under the ESA in the Study Area.

The Navy consulted with NMFS pursuant to section 7 of the ESA for the Study Area activities, and NMFS also consulted internally on the promulgation of this rule and the issuance of an LOA under section 101(a)(5)(A) of the MMPA and the implementing regulations. NMFS issued a biological and conference opinion concluding that the promulgation of the rule and issuance of a subsequent LOA are not likely to jeopardize the continued existence of threatened and endangered species under NMFS' jurisdiction and are not likely to result in the destruction or adverse modification of designated or proposed critical habitat in the Study Area. The biological and conference opinion is available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

The Assistant Administrator for Fisheries has determined that he Administrative Procedure Act's (APA) 30-day delay in the effective date requirement does not apply to this final rule because it relieves a restriction and because there is good cause for the rule to take effect on August 12, 2026. Section 553 of the APA provides that the required publication or service of a substantive rule shall be made not less than 30 days before its effective date with certain exceptions, including (1) for a substantive rule that relieves a restriction or (2) when the agency finds and provides good cause for foregoing delayed effectiveness (5 U.S.C. 553(d)(1) and (d)(3)).

This final rule is a substantive action that relieves the statutory prohibition on the taking of marine mammals, specifically, the incidental taking of marine mammals associated with the Navy's specified activities. Without this rule in place, the Navy would not have incidental take coverage for the specified activities in this rule absent a national security exemption under section 101(f) of the MMPA.

The Assistant Administrator has also determined that there is good cause under the APA to waive the 30-day delay in the effective date of this final rule. No individual or entity, other than the Navy, is affected by the provisions of these regulations, and the Navy does not require 30 days to prepare for implementation of the regulations. The Navy has been conducting SURTASS LFA sonar training and testing in the Study Area for over 20 years and take of marine mammals from these activities was most recently authorized under an LOA that is effective from August 12, 2019, through August 11, 2026, with similar requirements to those promulgated herein (https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navys-surveillance-towed-array-sensor-system-low-frequency). The Navy has requested that this final rule take effect on or before August 12, 2026, to accommodate issuance of an LOA to be in effect when the Navy's existing LOA expires on August 11, 2026, so as to not cause a disruption in training and testing activities. The final rule taking effect on August 12, 2026, will ensure that the MMPA final rule and LOA are in place by the time the previous authorization expires. Any delay in effectiveness of the final rule would result in either: (1) a suspension of planned naval training and testing, which would disrupt vital training and testing essential to national security; or (2) the Navy's non-compliance with the MMPA (should the Navy conduct training and testing without an LOA), thereby resulting in the potential for unauthorized takes of marine mammals. Moreover, the Navy is ready to implement the regulations immediately. For these reasons, NMFS finds that the 30-day delay requirement does not apply to this final rule.

Administrative practice and procedure, Endangered and threatened species, Fish, Fisheries, Marine mammals, Penalties, Reporting and recordkeeping requirements, Transportation, Wildlife.

Dated: July 23, 2026. Samuel D. Rauch III, Deputy Assistant Administrator for Regulatory Programs, National Marine Fisheries Service.

For the reasons set forth in the preamble, NMFS amends 50 CFR part 218 as follows:

PART 218--REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS

0 1. The authority citation for part 218 continues to read as follows:

Authority: 16 U.S.C. 1361 et seq.

0 2. Revise subpart X to read as follows:

Subpart X--Taking and Importing Marine Mammals; U.S. Navy Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) Sonar Training and Testing in the Central and Western North Pacific and Eastern Indian Oceans

Sec. 218.230 Specified activity and geographical region. 218.231 Effective dates. 218.232 Permissible methods of taking. 218.233 Prohibitions. 218.234 Mitigation requirements. 218.235 Requirements for monitoring and reporting. 218.236 Letter of Authorization. 218.237 Modifications of Letter of Authorization. 218.238-218.239 [Reserved]

Sec. 218.230 Specified activity and geographical region.

(a) Regulations in this subpart apply only to the U.S. Navy (Navy) for the taking of marine mammals that occurs in the area described in paragraph (b) of this section and that occurs incidental to the activities listed in paragraph (c) of this section. Requirements imposed on the Navy must be implemented by those persons they authorize or fund to conduct activities on their behalf.

(b) The taking of marine mammals by the Navy under this subpart may be authorized in a letter of authorization (LOA) only if it occurs within the Pacific Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) Sonar Study Area. The Pacific SURTASS LFA Sonar Study Area is delineated in Figure 1 to this paragraph (b) and includes the western and central North Pacific Ocean and eastern Indian Ocean, not including the western Indian Ocean or Sea of Okhotsk. BILLING CODE 3510-22-P

[GRAPHIC] [TIFF OMITTED] TR28JY26.328

BILLING CODE 3510-22-C

(c) The taking of marine mammals by the Navy is authorized only if it occurs incidental to the Navy conducting military readiness activities, including those in the following categories:

(1) Training;

(2) Maintenance and upgrades; and

(3) Exercises.

Sec. 218.231 Effective dates.

Regulations in this subpart are effective from August 12, 2026, through August 11, 2033.

Sec. 218.232 Permissible methods of taking.

(a) Under LOAs issued pursuant to Sec. 216.106 of this chapter and this subpart, the Navy may incidentally, but not intentionally, take marine mammals within the area described in

Sec. 218.230(b) by Level A harassment and Level B harassment associated with the use of SURTASS LFA sonar during activities listed in Sec. 218.230(c), provided the activity is in compliance with all terms, conditions, and requirements of this subpart and the applicable LOA.

(b) The incidental take of marine mammals by the activities listed in Sec. 218.230(c) is limited to the following species:

Table 1 to Paragraph (b)

Species Stock

North Pacific right whale.............. No stock designation (NSD). Blue whale............................. NSD. Blue whale............................. Central North Pacific. Bryde's whale.......................... NSD. Bryde's whale.......................... Hawaii. Fin whale.............................. NSD. Fin whale.............................. Hawaii. Humpback whale......................... NSD. Humpback whale......................... Hawaii. Humpback whale......................... Western North Pacific. Antarctic minke whale.................. NSD. Minke whale............................ NSD. Minke whale............................ Hawaii. Omura's whale.......................... NSD. Sei whale.............................. NSD. Sei whale.............................. Hawaii. Sperm whale............................ NSD. Sperm whale............................ North Pacific. Sperm whale............................ Hawaii. Dwarf sperm whale...................... NSD. Dwarf sperm whale...................... Hawaii. Pygmy sperm whale...................... NSD. Pygmy sperm whale...................... Hawaii. Baird's beaked whale................... NSD. Blainville's beaked whale.............. NSD. Blainville's beaked whale.............. Hawaii. Deraniyagala's beaked whale............ NSD. Ginkgo-toothed beaked whale............ NSD. Goose-beaked whale..................... NSD. Goose-beaked whale..................... Hawaii. Hubbs' beaked whale.................... NSD. Longman's beaked whale................. NSD. Longman's beaked whale................. Hawaii. Stejneger's beaked whale............... NSD. False killer whale..................... NSD. False killer whale..................... Main Hawaiian Islands Insular. False killer whale..................... Hawaii Pelagic. Killer whale........................... NSD. Killer whale........................... Hawaii. Melon-headed whale..................... NSD. Melon-headed whale..................... Hawaiian Islands. Pygmy killer whale..................... NSD. Pygmy killer whale..................... Hawaii. Short-finned pilot whale............... NSD. Short-finned pilot whale............... Hawaii. Bottlenose dolphin..................... NSD. Bottlenose dolphin..................... Hawaii Pelagic. Common dolphin......................... NSD. Fraser's dolphin....................... NSD. Fraser's dolphin....................... Hawaii. Northern right whale dolphin........... NSD. Pacific white-sided dolphin............ North Pacific. Pantropical spotted dolphin............ NSD. Pantropical spotted dolphin............ Hawaii Pelagic. Risso's dolphin........................ NSD. Risso's dolphin........................ Hawaii. Rough-toothed dolphin.................. NSD. Rough-toothed dolphin.................. Hawaii. Spinner dolphin........................ NSD. Spinner dolphin........................ Hawaii Pelagic. Striped dolphin........................ NSD. Striped dolphin........................ Hawaii Pelagic. Dall's porpoise........................ NSD. Northern fur seal...................... NSD. Steller sea lion....................... Western. Harbor seal............................ California. Ribbon seal............................ NSD.

Hawaiian monk seal..................... Hawaii. Ringed seal............................ NSD. Spotted seal........................... Bering.

Sec. 218.233 Prohibitions.

Except incidental take described in Sec. 218.232 and authorized by an LOA issued under Sec. 216.106 of this chapter and this subpart, it shall be unlawful for any person to do the following in connection with the activities described in this subpart:

(a) Violate, or fail to comply with, the terms, conditions, and requirements of this subpart or an LOA issued under Sec. 216.106 of this chapter and this subpart;

(b) Take any marine mammal not specified in Sec. 218.232(b);

(c) Take any marine mammal specified in Sec. 218.232(b) in any manner other than as specified in the LOA;

(d) Take a marine mammal specified in Sec. 218.232(b) after NMFS determines such taking results in more than a negligible impact on the species or stock of such marine mammal; or

(e) Take a marine mammal specified in Sec. 218.232(b) after NMFS determines such taking is having, or may have, an unmitigable adverse impact on the availability of the species or stock for taking for subsistence uses.

Sec. 218.234 Mitigation requirements.

When conducting the activities identified in Sec. 218.230(c), the mitigation measures contained in this section and any LOA issued under Sec. 216.106 of this chapter and this subpart must be implemented by Navy personnel or contractors who are trained according to the requirements in the LOA. If Navy contractors are serving on behalf of Navy personnel, Navy contractors must follow the mitigation applicable to Navy personnel. These mitigation measures include, but are not limited to:

(a) General operating procedures. Prior to SURTASS LFA sonar activities, the Navy must promulgate executive guidance for the administration and execution of and compliance with the regulations in this subpart and LOA.

(b) Manned surface vessel mitigation. Manned surface vessel mitigation applies to Auxiliary General Ocean Surveillance (T-AGOS) vessels underway and must be implemented to the maximum extent practical based on the prevailing circumstances, including consideration of safety of vessels, towing platforms, and crews, as well as maneuverability restrictions, consistent with the following:

(1) Immediately prior to getting underway and while underway, Lookouts will observe for marine mammals;

(2) While underway, Navy personnel must maneuver the manned surface vessels (which may include reducing speed) to maintain a distance of at least 457.2 meters (m) (500 yards (yd)) around observed whales and 182.9 m (200 yd) around all other marine mammals (except bow- or wake- riding dolphins), providing it is safe to do so. No further action is necessary if a dolphin continues to approach the vessel after the vessel has made one course and/or speed change.

(3) Pedestal-mounted `Big Eye' (20 x 110 millimeter (mm)) binoculars (if installed) shall be used to assist in the detection of marine mammals in the vicinity of the vessel. If the presence of marine mammals is detected acoustically, Lookouts posted on the vessel shall increase the vigilance of their visual observation.

(4) Manned surface vessel mitigation will not be implemented if one or more of the following conditions applies:

(i) Dolphins are determined to be intentionally swimming at the bow, alongside the vessel or vehicle, or directly behind the vessel or vehicle (e.g., to bow-ride or wake-ride);

(ii) The vessel's safety is threatened; or

(iii) Doing so is impractical based on mission requirements (e.g., restricted ability to maneuver during towing activities).

(c) SURTASS LFA sonar mitigation zone; suspension and delay. If a marine mammal is detected, through monitoring required under Sec. 218.235, within or about to enter within 2,000 yd (1.8 kilometers (km)) of the SURTASS LFA source (i.e., the LFA mitigation zone), Navy personnel must immediately delay or suspend SURTASS LFA sonar transmissions.

(d) Recommencement of SURTASS LFA sonar transmissions. The following requirements for commencement or recommencement of SURTASS LFA sonar transmissions apply:

(1) Navy personnel must not commence or recommence SURTASS LFA sonar transmissions earlier than 15 minutes after:

(i) All marine mammals have left the area of the 2,000-yd (1.8 km) LFA sonar mitigation zone; and

(ii) There is no further detection of any marine mammal within the 2,000-yd (1.8 km) LFA sonar mitigation zone as determined by the visual, passive acoustic, and active acoustic high frequency monitoring described in Sec. 218.235.

(2) [Reserved]

(e) Ramp-up of the high-frequency/marine mammal monitoring (HF/M3) active sonar. The following requirements for ramp-up procedures for the HF/M3 active sonar apply:

(1) Prior to full-power use, Navy personnel must ramp up the HF/M3 active sonar power level beginning at a maximum source sound pressure level of 180 decibels referenced to 1 microPascal (dB re 1 [mu]Pa) root-mean-square (RMS) sound pressure level (SPL) in 10-dB increments to full operating levels over a period of no less than 5 minutes. Navy personnel must implement this ramp-up procedure:

(i) At least 30 minutes prior to any SURTASS LFA sonar transmissions; and

(ii) Any time after the HF/M3 source has been powered down for more than 2 minutes.

(2) Navy personnel must not increase the HF/M3 SPL once a marine mammal is detected; and

(3) Ramp-up may recommence once marine mammals are no longer detected by all of the monitoring methods.

(f) Geographic mitigation. The Navy must implement the geographic mitigation requirements described in paragraphs (f)(1) through (f)(3) of this section.

(1) The activities specified in Sec. 218.230(c) must be conducted such that:

(i) The received level of SURTASS LFA sonar transmissions will not exceed 180 dB re 1 [mu]Pa RMS SPL within 22 km (12 nautical miles (nmi)) from any emergent land, including offshore islands;

(ii) The received level of SURTASS LFA sonar transmissions will not exceed 180 dB re 1 [mu]Pa RMS SPL at a distance of 1 km (0.5 nmi) seaward of the outer perimeter of any Offshore Biologically Important Area (OBIA) in

the SURTASS LFA Study Area during the effective period specified. OBIAs and the related effective periods are listed in paragraph (f)(2) of this section or may be subsequently identified through the adaptive management process specified in Sec. 218.237(c)(1). The boundaries and effective periods of the OBIAs will be kept on file in NMFS' Office of Protected Resources (OPR) and on its website.

(iii) No more than 25 percent of the sound source amount analyzed (no more than 275 hours in a given year) of SURTASS LFA sonar for training and testing will be conducted within 18.5 km (10 nmi) of any single OBIA during any year; and

(iv) SURTASS LFA sonar activities will not occur within territorial seas of foreign nations, which are areas from 0-22 km (0-12 nmi) from shore.

(2) Figure 1 to this paragraph (f)(1) shows the location of the OBIAs. Table 1 to paragraph (f)(1) shows the specified timeframes when the requirements from paragraph (f)(1) apply. BILLING CODE 3510-22-P

[GRAPHIC] [TIFF OMITTED] TR28JY26.329

BILLING CODE 3510-22-C

Table 1 to Paragraph (f)(1)--OBIAs for Marine Mammals in the Pacific SURTASS LFA Sonar Study Area

Relevant marine

OBIA No. Name Location/water body mammal species Effective period

26....................... Main Hawaiian Central North Humpback whale...... November through

Islands. Pacific Ocean. April. 27....................... Northwestern Central North Humpback whale...... December through

Hawaiian Islands. Pacific Ocean. April. 28....................... Mariana Islands..... Western North Humpback whale...... December through

Pacific Ocean. May. 29....................... Ryukyu-Philippines.. Western North Humpback whale...... January through

Pacific Ocean. April. 30....................... Ogasawara--Sperm Western North Sperm whale......... June through

whale. Pacific Ocean. September. 31....................... Ogasawara-Kazin-- Western North Humpback whale...... December through

Humpback whale. Pacific Ocean. May. 32....................... Honshu.............. Western North Gray whale.......... January through

Pacific Ocean. May. 33....................... Southeast Kamchatka. Western North Fin, gray (Western Year-round.

Pacific Ocean. North Pacific

stock), humpback,

and North Pacific

right whale. 34....................... Gulf of Thailand.... Eastern Indian Ocean Bryde's whale....... April through

November. 35....................... Western Australia-- Eastern Indian Ocean Blue (pygmy) whale.. May through

Blue whale. November. 36....................... Western Australia-- Eastern Indian Ocean Humpback whale...... May through

Humpback whale. December. 37....................... Southern Bali....... Eastern Indian Ocean Blue (pygmy), August through

Bryde's, humpback, November.

Omura's, sei, and

sperm whale. 38....................... Swatch-of-No-Ground Northern Bay of Bryde's whale....... Year-round.

(SoNG). Bengal. 39....................... Sri Lanka........... Eastern Indian Ocean Blue (pygmy) and October through

sperm whale. April. 40....................... Maldives Archipelago Central Indian Ocean Blue (pygmy), October through

Bryde's, humpback, May.

and sperm whale. 41....................... Northeast Arabian Arabian Sea......... Blue, Bryde's, and Year-round.

Sea. humpback (Arabian

Sea stock) whale. 42....................... South of Java Island East Indian Ocean... Blue (pygmy) whale.. May through

November. 43....................... South of Lombok East Indian Ocean... Blue (pygmy) whale.. May through

Sumbawa Islands. November. 44....................... Southeast Kamchatka Western North North Pacific right April through

Offshore. Pacific Ocean. whale. October.

(3) Should national security require the Navy to exceed a requirement in paragraph (f)(1)(iii) of this section, personnel conducting the activity are required to obtain approval through the chain of command prior to commencement of the activity. The Navy must provide NMFS with notification as soon as is practicable and include the information (e.g., sonar hours in exceedance of 25 percent) in its annual activity reports submitted to NMFS.

(g) Cetacean live stranding. In the event of a cetacean live stranding (or near-shore atypical milling) event within the Study Area or within 50 km (27 nmi) of the boundary of the Study Area, where the NMFS Marine Mammal Stranding Network is engaged in herding or other interventions to return animals to the water, NMFS OPR will advise the Navy of the need to implement shutdown procedures for all active acoustic sources within 50 km of the stranding. Following this initial shutdown, NMFS will communicate with the Navy to determine whether circumstances support modification of the shutdown zone. The Navy may decline to implement all or part of the shutdown if the holder of the LOA, or his/her designee, determines that it is necessary for national security. Shutdown procedures for live stranding or milling cetaceans include the following:

(1) Shutdown no longer needed. If at any time, the marine mammal(s) die or are euthanized, or if herding/intervention efforts are stopped, NMFS will immediately advise that the shutdown around the animals' location is no longer needed;

(2) Shutdown procedures remain in effect. Otherwise, shutdown procedures must remain in effect until NMFS determines and advises that all live animals involved have left the area (either of their own volition or following an intervention); and

(3) Further observations. If further observations of the marine mammals indicate the potential for re-stranding, additional coordination with NMFS will be required to determine what measures are necessary to minimize that likelihood (e.g., extending the shutdown or moving operations farther away) and to implement those measures as appropriate.

Sec. 218.235 Requirements for monitoring and reporting.

The Navy must implement the following monitoring and reporting requirements when conducting the specified activities:

(a) Notification of take. If the Navy reasonably believes that the specified activity identified in Sec. 218.230 resulted in the mortality or serious injury of any marine mammals, or in any Level A harassment or Level B harassment of marine mammals not identified in this subpart, then the Navy must notify NMFS immediately or as soon as operational security considerations allow.

(b) Monitoring and reporting under the LOA. The Navy must conduct all monitoring and reporting required under the LOA.

(c) Notification of injured, live stranded, or dead marine mammals. Navy personnel must abide by the Notification and Reporting Plan, which sets out notification, reporting, and other requirements when dead, injured, or live stranded marine mammals are detected. The Notification and Reporting Plan is available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

(d) Mitigation monitoring. The Navy must conduct all monitoring required under the LOA, including:

(1) Visual Observations. Visual observations must be conducted by trained Lookouts on the vessel's bridge using standard binoculars (7x) and the naked eye. Pedestal-mounted `Big Eye' (20 x 110 mm) binoculars (if installed) must be used to assist in the detection of marine mammals in the vicinity of the vessel.

(i) Lookouts must conduct visual monitoring from the vessel's bridge during all daylight hours (30 minutes before sunrise until 30 minutes after sunset);

(ii) During training and testing activities that employ SURTASS LFA sonar in the active mode, Lookouts must

conduct visual monitoring beginning 30 minutes before sunrise or 30 minutes before SURTASS LFA sonar begins to transmit and continue until 30 minutes after sunset or until 15 minutes after the SURTASS LFA sonar transmissions cease;

(iii) Lookouts must log all detections of marine mammals during SURTASS LFA sonar transmissions during training and testing activities;

(iv) Lookouts must record the number, identification, bearing, and range of observed marine mammals during training and testing activities, and must identify marine mammals to the lowest taxonomic level possible; and

(v) Lookouts must continue visual observations until 15 minutes have passed since the last detection of the marine mammal.

(2) Passive Acoustic Monitoring. During activities specified in Sec. 218.230(c) that employ SURTASS LFA sonar in the active mode, Navy personnel must conduct passive acoustic monitoring using the SURTASS towed horizontal line array to detect vocalizing marine mammals.

(i) Passive acoustic monitoring must begin 30 minutes before the SURTASS LFA sonar begins to transmit and continue until 15 minutes after SURTASS LFA sonar transmissions cease; and

(ii) If a detected sound is estimated to be from a vocalizing marine mammal, the sonar technician must notify the senior military member-in-charge, who must alert the HF/M3 sonar operator and Lookouts (during daylight).

(3) Active Acoustic (HF/M3) Monitoring. During activities specified in Sec. 218.230(c) that employ SURTASS LFA sonar in the active mode, Navy personnel must use the HF/M3 sonar to detect, locate, and track marine mammals in relation to the SURTASS LFA sonar array and the LFA mitigation zone, subject to the ramp-up requirements in Sec. 218.234(e).

(i) HF/M3 sonar monitoring must begin 30 minutes before the SURTASS LFA sonar begins to transmit and continue until 15 minutes after SURTASS LFA sonar transmissions cease; and

(ii) If a marine mammal is detected during HF/M3 monitoring within the SURTASS LFA mitigation zone, the sonar operator must notify the senior military member-in-charge.

(4) Cessation of Monitoring. Navy personnel must continue monitoring either for at least 15 minutes after completion of the SURTASS LFA sonar training and testing transmission or, if marine mammals are exhibiting unusual changes in behavioral patterns, until behavior patterns return to normal or conditions prevent continued observations.

(e) Designation of qualified individuals. The Navy must designate qualified on-site individuals to conduct the mitigation, monitoring, and reporting activities specified in these regulations and LOA issued under Sec. Sec. 216.106 of this chapter and 218.236.

(f) Marine Mammal Monitoring Program. The Navy must continue to assess data from the Marine Mammal Monitoring Program and work toward making some portion of that data, after appropriate security reviews, available to scientists with appropriate clearances. Any portions of the analyses conducted by these scientists based on these data that are determined to be unclassified after appropriate security reviews will be made publicly available.

(g) Annual Pacific SURTASS LFA Study Area marine species monitoring report. The Navy must submit an unclassified annual report (Annual Pacific SURTASS LFA Study Area Marine Species Monitoring Report) of the Study Area marine species monitoring describing the implementation and results from the previous calendar year. Data collection methods will be standardized across range complexes and the Study Area to allow for comparison in different geographic locations. The draft report must be submitted annually to the Director, Office of Protected Resources, NMFS. NMFS will submit any comments or questions on the report within 3 months of receipt. The report will be considered final after the Navy has addressed NMFS' comments, or 3 months after submittal of the draft if NMFS does not provide comments on the draft report. The report must describe progress of knowledge made with respect to new or continuing scientific knowledge of marine mammals.

(h) Quick look reports. In the event that the sound source amount analyzed in the preambles of the Marine Mammal Protection Act (MMPA) proposed rule (91 FR 11618, March 10, 2026) and this final rule are exceeded within a given reporting year, the Navy must submit a preliminary report detailing the exceedance within 21 days after the anniversary date of issuance of the LOA.

(i) Annual Pacific SURTASS LFA training and testing report. The Navy must submit a classified and unclassified report (Annual Pacific SURTASS LFA Training and Testing Report) to the Director, Office of Protected Resources, NMFS, annually within 3 months of the 1-year anniversary of the date of the issuance of the LOA. For the final reporting year, the Navy must submit a final/close-out (year 7) Annual Pacific SURTASS LFA Training and Testing Report. NMFS will submit any comments or questions on the report within 1 month of receipt. The report will be considered final after the Navy has addressed NMFS' comments, or 1 month after submittal of the drafts if NMFS does not provide comments on the draft report.

(1) Annual Reports. The Annual Pacific SURTASS LFA Training and Testing Report must include elements listed below. The analysis in the report must be based on the data from the current year's report and data collected from previous annual reports.

(i) Dates, times, and locations of each vessel during each training and testing activity;

(ii) Information on sonar transmissions during each training and testing activity, including:

(A) Total annual hours or quantity of each bin of sonar used in all training and testing events,

(B) Cumulative sonar use quantity from previous years' reports through the current year, and

(C) Records of any sonar delays or suspensions due to the presence of marine mammals.

(iii) Marine mammal detection information during specified activities where mitigation was implemented:

(A) Date, time, and location of sighting;

(B) Species (if not possible, indication of whale/dolphin/ pinniped);

(C) Number of individuals;

(D) Initial Detection Sensor (e.g., visual, passive acoustic, HF/M3 sonar);

(E) Indication of specific type of platform observation was made from (including, for example, what type of surface vessel or testing platform);

(F) Length of time observers maintained visual contact with marine mammal;

(G) Sea state;

(H) Visibility;

(I) Sound source in use at the time of sighting;

(J) Indication of whether animal was less than 200 yd (182.9 m), 200 to 500 yd (182.9 to 457.2 m), 500 to 1,000 yd (457.2 to 914.4 m), 1,000 to 2,000 yd (914.4 m to 1.8 km), or greater than 2,000 yd (1.8 km) from sonar source;

(K) Whether operation of sonar sensor was delayed, or sonar was powered or shut down, and the length of delay;

(L) Bearing and range from the vessel; and

(M) For visual observations, Lookouts must report the observed behavior of the animal(s) in plain language and without trying to categorize in any way (such as

animal closing to bow ride, paralleling course/speed, floating on surface and not swimming, etc.) and if any calves were present.

(iv) Delays or suspensions of LFA sonar transmissions due to mitigation monitoring protocol. Information on marine mammal detections would include marine mammal type (i.e., whales, dolphins) and/or species identifications, number of marine mammals detected, time of detections, type of detection (visual, passive acoustic, HF/M3 sonar), bearing and range from the vessel, abnormal behavior (if any), and remarks or narrative as necessary.

(v) An evaluation (based on data gathered during the reporting year) of the effectiveness of mitigation measures designed to minimize the received level to which marine mammals may be exposed. This evaluation must identify the specific observations that support any conclusions the Navy reaches about the effectiveness of the mitigation.

(2) Final/close-out report. The final/close-out report at the conclusion of the authorization period (year 7) will also serve as the comprehensive close-out report and provide the annual totals for each sound source bin with a comparison to the annual amount analyzed and the 7-year total for each sound source bin with a comparison to the 7- year amount analyzed.

(j) National security requirement. If the Navy invokes the national security requirement described in Sec. 218.234(f)(3), Navy personnel must include information about the event in its Annual Pacific SURTASS LFA Training and Testing Report.

Sec. 218.236 Letter of Authorization.

(a) To incidentally take marine mammals pursuant to this subpart, the Navy must apply for and obtain an LOA.

(b) An LOA, unless suspended or revoked, may be effective for a period of time not to exceed the expiration date of this subpart.

(c) The LOA will set forth:

(1) Permissible methods of incidental taking;

(2) Geographic areas for incidental taking;

(3) Means of effecting the least practicable adverse impact (i.e., mitigation) on the species and stocks of marine mammals and their habitat; and

(4) Requirements for monitoring and reporting.

(d) Issuance of the LOA must be based on a determination that the level of taking is consistent with the findings made for the total taking allowable under the regulations of this subpart.

(e) Notice of issuance, modification, or denial of the LOA will be published in the Federal Register within 30 days of a determination.

(f) In the event of projected changes to mitigation, monitoring, or reporting measures required by an LOA, the Navy must apply for and obtain a modification of the LOA under Sec. 218.237.

Sec. 218.237 Modifications of Letters of Authorization.

(a) NMFS may modify the mitigation, monitoring, or reporting measures in a LOA issued under Sec. Sec. 216.106 of this chapter and 218.236 of this subpart at the request of the Navy or NMFS' own initiative if:

(1) The anticipated effects of the modified measure are the same as those described and analyzed for this subpart;

(2) The modified measure has a reasonable likelihood of effectiveness;

(3) NMFS determines the modified measure does not change the findings made for this subpart; and

(4) Navy concurs with the modified measure and that, where applicable, it is practicable for the Navy in the context of personnel safety, practicality of implementation, and impacts on the effectiveness of the military readiness activity.

(b) If modifications to the mitigation, monitoring, or reporting measures are substantial NMFS will publish a notice of the proposed LOA modification in the Federal Register and solicit public comment.

Sec. Sec. 218.238-218.239 [Reserved]

[FR Doc. 2026-15206 Filed 7-27-26; 8:45 am] BILLING CODE 3510-22-P