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Marine Mammal Protection Act; Draft Revised Stock Assessment Reports for the Pacific Walrus and Three Northern Sea Otters

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Fish and Wildlife Service, Interior.


Notice of availability; request for comments.


In accordance with the Marine Mammal Protection Act of 1972, as amended (MMPA), and its implementing regulations, we, the U.S. Fish and Wildlife Service (Service), have developed a draft revised marine mammal stock assessment report (SAR) for the Pacific walrus stock and for each of the following three northern sea otter stocks in Alaska: Southwest, Southcentral, and Southeast. We now make the SARs available for public review and comment.


Comments must be received by July 17, 2013.


Document Availability: You may view the draft revised stock assessment reports on under Docket No. FWS-R7-ES-2012-0019. You may also view them in Adobe Acrobat format by navigating to the species information page at​fisheries/​mmm/​reports.htm. Alternatively, you may contact the Chief, U.S. Fish and Wildlife Service, Marine Mammals Management Office, 1011 East Tudor Road, Anchorage, AK 99503; telephone: 907-786-3800.

Written Comments: You may submit comments on the draft revised stock assessment reports by one of the following methods:

  • U.S. mail or hand-delivery: Public Comments Processing, Attn: Docket No. FWS-R7-ES-2012-0019; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS 2042-PDM; Arlington, VA 22203; or
  • Federal eRulemaking Portal: Follow the instructions for submitting comments to Docket No. FWS-R7-ES-2012-0019.

Please indicate to which revised stock assessment report(s)—the Pacific walrus, or the southeast, southcentral, or southwest Alaska northern sea otter stock—your comments apply. We will not accept email or faxes. We will post all comments on This generally means that we will post any personal information you provide us.

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Charles S. Hamilton, Marine Mammals Management Office, 800-362-5148 (telephone). Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service at 800-877-8339.

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We announce for review and comment the availability of draft revised marine mammal stock assessment reports (SAR) for the Pacific walrus (Odobenus rosmarus divergens) stock and for each of the following three northern sea otter (Enhydra lutris kenyoni) stocks in Alaska: Southwest, Southcentral, and Southeast.

Under the MMPA (16 U.S.C. 1361 et seq.) and its implementing regulations in the Code of Federal Regulations (CFR) at 50 CFR part 18, we regulate the taking, possession, transportation, purchasing, selling, offering for sale, exporting, and importing of marine mammals. One of the goals of the MMPA is to ensure that stocks of marine mammals occurring in waters under U.S. jurisdiction do not experience a level of human-caused mortality and serious injury that is likely to cause the stock to be reduced below its optimum sustainable population level (OSP). OSP is defined under the MMPA as “* * * the number of animals which will result in the maximum productivity of the population or the species, keeping in mind the carrying capacity of the habitat and the health of the ecosystem of which they form a constituent element” (16 U.S.C. 1362(3)(9)).

To help accomplish the goal of maintaining marine mammal stocks at their OSPs, section 117 of the MMPA requires the Service and the National Marine Fisheries Service (NMFS) to prepare a SAR for each marine mammal stock that occurs in waters under U.S. jurisdiction. Each SAR must include:

1. A description of the stock and its geographic range;

2. A minimum population estimate, maximum net productivity rate, and current population trend;

3. An estimate of human-caused mortality and serious injury;

4. A description of commercial fishery interactions;

5. A categorization of the status of the stock; and

6. An estimate of the potential biological removal (PBR) level.

The MMPA defines the PBR as “the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its OSP” (16 U.S.C. 1362(3)(20)). The PBR is the product of the minimum population estimate of the stock (Nmin); one-half the maximum theoretical or estimated net productivity rate of the stock at a small population size (Rmax); and a recovery factor (Fr) of between 0.1 and 1.0. This can be written as:

PBR = (Nmin)(1/2 of the Rmax)(Fr)

Section 117 of the MMPA requires the Service and NMFS to review the SARs (a) At least annually for stocks that are specified as strategic stocks, (b) at least annually for stocks for which significant new information is available, and (c) at least once every 3 years for all other stocks. If our review of the status of a stock indicates that it has changed or may be more accurately determined, then the SAR must be revised accordingly.

A strategic stock is defined in the MMPA as a marine mammal stock “(a) for which the level of direct human-caused mortality exceeds the PBR level; (b) which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.) [the “ESA”], within the foreseeable future; or (c) which is listed as a threatened or endangered species under the ESA, or is designated as depleted under [the MMPA].” 16 U.S.C. 1362(3)(19).

The Pacific walrus SAR was last revised in December of 2009. In the final 2009 revised stock assessment, we classified the Pacific walrus as a strategic stock because the total human-caused mortality or removals exceeded PBR. Therefore, the Service has reviewed the stock assessment for the Pacific walrus annually and, in 2010, concluded that revision of the SAR was not warranted at that time because the status of the stock had not changed significantly, nor could it be more Start Printed Page 23285accurately determined. SARs for the Southwest, Southcentral, and Southeast stocks of northern sea otters were last revised in August of 2008. The Southwest stock of northern sea otter qualifies as a strategic stock due to its listing as a threatened species under the ESA; therefore, the Service has reviewed the SAR for the Southwest stock annually in 2009 and 2010 and concluded both times that revision of the SAR was not warranted because the status of the stock had not changed, nor could it be more accurately determined. The Southcentral and Southeast stocks of northern sea otter are considered non-strategic, and the Service also reviewed these SARs annually in 2009 and 2010 due to the availability of significant new information. During both these reviews, the Service determined that revision of the SARs for the Southcentral and Southeast stocks of northern sea otter was not warranted. However, upon review in 2011, the Service determined that revision was warranted for the Pacific walrus stock, as well as the Southwest, the Southcentral, and the Southeast northern sea otter stocks; the Service has consulted with the Alaska Regional Scientific Review Group concerning these revisions.

The following table summarizes the information we are now making available in the draft revised stock assessment reports for the Pacific walrus and the southwest, southcentral and southeast stocks of the northern sea otter, which lists the stock's Nmin, Rmax, Fr, PBR, annual estimated human-caused mortality and serious injury, and status. After consideration of any public comments we receive, the Service will revise and finalize the SARs as appropriate for these stocks. We will publish a notice of availability and summary of the final SARs, including responses to submitted comments.

Summary: Draft Revised Stock Assessment Reports for the Pacific Walrus, and Southwest, Southcentral, and Southeast Stocks of the Northern Sea Otter

StockNminRmaxFrPBRAnnual estimated human-caused mortality and serious injury (5-year average)Stock status
Pacific Walrus129,0000.080.52,580124,852Strategic.
Northern Sea Otter, Southwest Stock45,0640.200.1450<1076Strategic.
Northern Sea Otter, Southcentral Stock14,6610.201.01,4661293Non-Strategic.
Northern Sea Otter, Southeast Stock21,7980.201.02,179Unknown447Non-Strategic.

Public Availability of Comments

Before including your address, phone number, email address, or other personal identifying information in your comment, you should be aware that your entire comment—including your personal identifying information—may be made publicly available at any time. While you can ask us in your comment to withhold your personal identifying information from public review, we cannot guarantee that we will be able to do so.


In accordance with section 117(b)(1) of the MMPA, we include in this notice a list of the sources of information or published reports upon which we based the draft revised SAR. The Service consulted technical reports, conference proceedings, refereed journal publications, and scientific studies prepared or issued by Federal agencies, nongovernmental organizations, and individuals with expertise in the fields of marine mammal biology and ecology, population dynamics, Alaska Native subsistence use of marine mammals, modeling, and commercial fishing technology and practices.

These agencies and organizations include: the Service, the U.S. Geological Survey, the National Oceanic and Atmospheric Administration, the National Park Service, the Arctic Institute, the North American Wildlife and Natural Resource Conference, the Marine Mammals of the Holarctic V Conference, the Aleutian Islands Risk Assessment Management Team, the Exxon Valdez Restoration Project, and the Outer Continental Shelf Environmental Assessment Program. In addition, the Service consulted publications such as the Journal of Wildlife Management, Conservation Biology, Marine Mammal Science, Ecological Applications, Biological Conservation, Aquatic Mammals, and Journal of Zoology, as well as other refereed journal literature, technical reports, and data sources in the development of these SARs.

A complete list of citations to the scientific literature relied on for each of the four draft revised SARs is available on the Federal eRulemaking portal ( under Docket No. FWS-R7-ES-2012-0019. The list can also be viewed in Adobe Acrobat format at​fisheries/​mmm/​reports.htm.

In the past, the Service has published a complete list of citations to each technical report, scientific paper, and journal publication upon which the draft revised SAR is based at the end of the Notice of Availability. However, in order for the public to more easily understand how the agency has used and interpreted the sources relied upon in the draft revised SARs, the Service is making the complete list of literature citations available at the end of each of the draft revised SARs. In recognition that the public typically reviews our draft SARs, or any revision thereof, in conjunction with the list of supporting literature citations found at the end of draft SARs, the Service believes it is unnecessary to also publish the complete list of references separately in this notice of availability. Instead, we are including the complete list of references in the draft revised SARs as a single document available to the public through the Government's regulations portal and our own Web page.


The authority for this action is the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et al.).

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Dated: April 9, 2013.

Rowan W. Gould,

Acting Director, Fish and Wildlife Service.

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[FR Doc. 2013-09067 Filed 4-17-13; 8:45 am]