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Commerce Department, National Oceanic and Atmospheric Administration

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

Published July 28, 2026. Takes effect August 12, 2026, printed at 91 FR 47664, amending 50 CFR 218. 35,354 words.

In plain English

Navy work at sea can disturb sea mammals. This sets the terms for that.

Read it at the Federal Register →

What the Rule Says It Does

NMFS, upon request from the U.S. Department of the Navy (Navy), issues these regulations pursuant to the Marine Mammal Protection Act (MMPA) to govern the taking of marine mammals incidental to training and testing activities using Surveillance Towed Array Sensor System (SURTASS) Low Frequency Active (LFA) sonar systems in the western and central North Pacific and eastern Indian oceans over the course of 7 years from August 2026 through August 2033. These regulations allow for the issuance of a letter of authorization (LOA) for the incidental take of marine mammals during specified activities and timeframes, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species and their habitat, and establish requirements pertaining to the monitoring and reporting of such taking. The Navy's activities are considered military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA) and the NDAA for Fiscal Year 2019 (2019 NDAA).

This is the rule's own summary, as the Federal Register prints it.

The Order It Names

The rule names this order itself. What it does about it is a reading, and none is recorded here.

On the Face of the Rule

As filed

[Federal Register Volume 91, Number 143 (Tuesday, July 28, 2026)] [Rules and Regulations] [Pages 47664-47711] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 2026-15206]

Vol. 91

Tuesday,

No. 143

July 28, 2026

Part III

Department of Commerce

National Oceanic and Atmospheric Administration

50 CFR Part 218

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; Final Rule

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 260723-0177] RIN 0648-BN61

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

AGENCY

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION

Final rule; notification of issuance of Letter of Authorization.

DATES

Effective from August 12, 2026, through August 11, 2033.

ADDRESSES

A copy of the Navy's Incidental Take Authorization (ITA) application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems accessing these documents, please call the contact listed below (see FOR FURTHER INFORMATION CONTACT).

FOR FURTHER INFORMATION CONTACT

Alyssa Clevenstine, Office of Protected Resources, NMFS, (301) 427-8401.

The fields the Federal Register prints at the head of the rule, quoted as printed. Its summary is quoted above.

Why the Agency Says It Is Doing This

SUPPLEMENTARY INFORMATION

Purpose and Need for Regulatory Action

These regulations, issued under the authority of the MMPA (16 U.S.C. 1361 et seq.), allow for the authorization of take of marine mammals incidental to the Navy's training and testing activities (which qualify as military readiness activities) using SURTASS LFA sonar in the western and central North Pacific Ocean and eastern Indian Ocean (see figure 2-1 of this notice and LOA application (hereafter referred to as the application)). Please see the Legal Authority for the Final Action section for relevant definitions.

The passage that opens the rule's preamble, where the agency sets out what it is doing and on what authority. Every heading that follows it is listed below.

What the Rule Contains

Every heading the Federal Register prints in this rule, in the order it prints them. 44 headings, 35,354 words in all.

  1. AGENCYOn its face · 13 words
  2. ACTIONOn its face · 10 words
  3. SUMMARYOn its face · 166 words
  4. DATESOn its face · 10 words
  5. ADDRESSESOn its face · 50 words
  6. FOR FURTHER INFORMATION CONTACTOn its face · 13 words
  7. SUPPLEMENTARY INFORMATIONPreamble · 2 words
  8. Purpose and Need for Regulatory ActionPreamble · 87 words
  9. Legal Authority for the Final ActionPreamble · 481 words
  10. Summary of Major Provisions Within the Final RulePreamble · 144 words
  11. Summary of RequestPreamble · 503 words
  12. Description of Specified ActivityPreamble · 219 words
  13. Comments and ResponsesPreamble · 5,039 words
  14. Changes From the Proposed Rule to the Final RulePreamble · 2,570 words
  15. Critical HabitatPreamble · 561 words
  16. Biologically Important AreasPreamble · 1,165 words
  17. Unusual Mortality EventsPreamble · 44 words
  18. Potential Effects of Specified Activities on Marine Mammals and Their HabitatPreamble · 1,078 words
  19. Estimated Take of Marine MammalsPreamble · 810 words
  20. Estimated Take From Acoustic StressorsPreamble · 3,277 words
  21. Mitigation MeasuresPreamble · 377 words
  22. Implementation of Least Practicable Adverse Impact StandardPreamble · 1,363 words
  23. Assessment of Mitigation Measures for the Study AreaPreamble · 2,350 words
  24. Mitigation MonitoringPreamble · 797 words
  25. Activity-Based MitigationPreamble · 990 words
  26. Geographic MitigationPreamble · 419 words
  27. Offshore Biologically Important Areas for SURTASS LFA SonarPreamble · 2,368 words
  28. Mitigation ConclusionsPreamble · 276 words
  29. MonitoringPreamble · 219 words
  30. ReportingPreamble · 139 words
  31. Analysis and Negligible Impact DeterminationPreamble · 5 words
  32. IntroductionPreamble · 481 words
  33. AnalysisPreamble · 67 words
  34. HarassmentPreamble · 3,089 words
  35. DeterminationPreamble · 58 words
  36. Unmitigable Adverse Impact Analysis and DeterminationPreamble · 129 words
  37. Adaptive Management and Modifications of Letters of AuthorizationPreamble · 354 words
  38. ClassificationPreamble · 251 words
  39. National Marine Sanctuaries ActPreamble · 82 words
  40. National Environmental Policy ActPreamble · 145 words
  41. Regulatory Flexibility ActPreamble · 94 words
  42. Paperwork Reduction ActPreamble · 54 words
  43. Waiver of Delay in Effective DatePreamble · 451 words
  44. List of Subjects in 50 CFR Part 218Regulatory text · 4,407 words

The Rest of the Text

This rule runs to 35,354 words. The rest of it is set out over 2 pages, split at the rule's own headings so that no heading is parted from the words printed under it.

How to cite this
  1. The rule itself

    Commerce Department, National Oceanic and Atmospheric Administration, “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,” 91 FR 47664 (July 28, 2026). Effective August 12, 2026.
    https://www.federalregister.gov/documents/2026/07/28/2026-15206/takes-of-marine-mammals-incidental-to-specified-activities-taking-marine-mammals-incidental-to-us

  2. This page

    “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,” a final rule naming an order indexed here. Read the Mandate, https://readthemandate.org/rules/rule-2026-15206/ (retrieved October 10, 2026).

Cite the document when the claim is about what the document says. Cite this page when the indexing, the wording or the record of what has happened is what is being relied on.

How This Rule Is Set Out

Federal Register documents are United States government works and are not under copyright, so the rule is here whole rather than cut to an excerpt. It is split at the headings the Register itself prints: the line it is filed under, the captioned fields on its face, the preamble where the agency says what it is doing and why, and the amendments to the Code of Federal Regulations. No passage is shortened. This rule is long enough that its text is set out over 2 pages rather than one.

Two things the Register prints are not reproduced: the running head it repeats at every page break, and the tables it sets as pictures rather than as words. Its own marker for one of those tables, [GRAPHIC] [TIFF OMITTED], is left standing where the table was, so a reader can see that something is there and follow the link to the page it is on.

A heading with nothing quoted under it is one the rule prints on its own, with the words that follow it set under the headings beneath.