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Endangered and Threatened Wildlife and Plants; Notice of Designation of the Northern Sea Otter in the Aleutian Islands as a Candidate Species

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Fish and Wildlife Service, Interior.


Notice of designation of a candidate species.


In this document, we present information on the recent addition of the northern sea otter (Enhydra lutris kenyoni) found in the Aleutian Islands to the list of candidates for listing under the Endangered Species Act of 1973, as amended. Identification of candidate taxa can assist environmental planning efforts by providing advance notice of potential listings, allowing resource managers to alleviate threats and thereby possibly remove the need to list taxa as endangered or threatened. Even if we subsequently list this candidate species, the early notice provided here could result in fewer restrictions on activities by prompting candidate conservation measures to alleviate threats to this species.

We also announce the availability of the candidate and listing priority assignment form for this candidate species. This document describes the status and threats that we evaluated to determine that the northern sea otter in the Aleutian Islands warrants consideration for listing, and to assign a listing priority to this species.

We request additional status information that may be available for the northern sea otter. We will consider this information in evaluating, monitoring, and developing conservation strategies for this species.


We will accept comments on this document at any time.


Submit written comments and data regarding the northern sea otter to the Marine Mammals Management Office, U.S. Fish and Wildlife Service, 1011 E. Tudor Road, Anchorage, Alaska 99503.

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Douglas Burn, Wildlife Biologist, Marine Mammals Management Office at the above address, or telephone 907/786-3800 or facsimile 907/786-3816.

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The Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), requires that we list taxa of wildlife and plants that are endangered or threatened, based on the best available scientific and commercial information. As part of this program, we also identify taxa that we regard as candidates for listing. Candidate taxa are those taxa for which we have on file sufficient information to support issuance of a proposed rule to list under the Act. In addition to our annual review of all candidate taxa (64 FR 57534; October 25, 1999), we have an on-going review process, particularly to update taxa whose status may have changed markedly.

Section 3 of the Act generally defines an endangered species as any species which is in danger of extinction throughout all or a significant portion of its range, and a threatened species as any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act:

(A) The present or threatened destruction, modification, or curtailment of the species' habitat or range;

(B) Overutilization of the species for commercial, recreational, scientific, or educational purposes;

(C) Disease or predation affecting the species;

(D) The inadequacy of existing regulatory mechanisms to protect the species; and

(E) Other natural or manmade factors affecting the species' continued existence. Start Printed Page 67344

We are required to make the listing determination “solely on the basis of the best scientific and commercial data available” and “taking into account those efforts, if any, being made by any State or foreign nation, or any political subdivision of a State or foreign nation, to protect such species, whether by predator control, protection of habitat and food supply, or other conservation practices, within any area under its jurisdiction, or on the high seas.” Sections 4(a)(1) and 4(b)(1)(A) and our regulations at 50 CFR 424.11(f) require us to consider any State or local laws, regulations, ordinances, programs, or other specific conservation measures that either positively or negatively affect a species' status (i.e., efforts that create, exacerbate, reduce, or remove threats identified through the section 4(a)(1) analysis).

We maintain the list of candidate species for a variety of reasons, including: to provide advance knowledge of potential listings that could affect decisions of planners and developers; to solicit input from interested parties to identify those candidate taxa that may not require protection under the Act or additional taxa that may require the Act's protections; to solicit information on the status of species and measures necessary to conserve species, and to solicit information needed to prioritize the order in which we will propose taxa for listing. We encourage consideration of candidate taxa in environmental planning, such as in environmental impact analysis under the National Environmental Policy Act of 1969 (implemented at 40 CFR parts 1500-1508) and in local and Statewide land use planning.

According to our 1983 Listing Priority System (48 FR 43098; September 21, 1983), all species that are candidates for listing are assigned a listing priority number. This system ranks species according to—(1) the magnitude of threats they face, (2) the immediacy of these threats, and (3) the taxonomic distinctiveness of the entity that may be listed. Listing priority numbers range from 1 (highest priority) to 12 (lowest priority). We will complete proposals to list candidate species, based on their listing priority, to the extent that our resources for listing activities and our workload for other listing activities will allow.

This notice provides specific explanations of why we classified the northern sea otter as a candidate. This decision was approved by the Service's Director Jamie Rappaport Clark, on August 22, 2000. It is important to note that candidate assessment is an ongoing function and changes in status should be expected. If we remove taxa from the candidate list, they may be restored to candidate status if additional information supporting such a change becomes available to us. We issue requests for such information in a Candidate Notice of Review published in the Federal Register every year.


The worldwide population of sea otters in the early 1700s has been estimated at 150,000 (Kenyon 1969) to 300,000 (Johnson 1982). Extensive commercial hunting of sea otters began following the arrival in Alaska of Russian explorers in 1741 and continued during the 18th and 19th centuries. By the time sea otters were afforded protection from commercial harvests by international treaty in 1911, the species was nearly extinct throughout its range, and may have numbered only 1,000-2,000 individuals (Kenyon 1969).

Following the international treaty in 1911, only 13 isolated remnant populations scattered throughout the historic range remained. However, once commercial harvests ceased, these populations began to grow and recolonize their former range. Today three subspecies of sea otter have been identified (Wilson et al. 1991). The northern sea otter contains two subspecies: Enhydra lutris kenyoni which occurs from the Aleutian Islands to Oregon, and Enhydra lutris lutris which occurs in the Kuril Islands, Kamchatka Peninsula, and Commander Islands in Russia. The third subspecies, Enhydra lutris nereis, occurs in California and is known as the southern sea otter.

The period of recolonization was marked by high reproductive rates and range expansion. Survey data indicate that otters were present in all island groups in the Aleutians by the 1980s (Brueggeman et al. 1988, Estes 1990). Calkins and Schneider (1985) calculated the sea otter population in the Aleutians as 55,100 to 73,700 individuals, which represented over half the Alaska population. The entire Aleutian archipelago was not systematically surveyed again until 1992. During these surveys Evans et al. (1997) estimated the Aleutian Islands sea otter population as 19,157 ± 3,281. The most striking results of this survey were that sea otter density and abundance in the Rat, Delarof, and western Andreanof Islands had unexpectedly declined by more than 50 percent. Boat-based surveys of sea otters at several islands in the Near, Rat, and Andreanof Islands further documented an ongoing decline of sea otters during the 1990s (Estes et al. 1998). As few as 6,000 sea otters may remain in the Aleutians today (U.S. Fish & Wildlife Service, Unpublished Data).

Potential threats include both natural fluctuations and human activities, which may have caused changes in the Bering Sea ecosystem. Subsistence hunting occurs at very low levels and does not appear to be a factor in the decline. While disease, starvation, and contaminants have not been implicated at this time, additional evaluation of these factors is warranted. The hypothesis that predation by killer whales is causing the sea otter decline (Estes et al. 1998) should also be studied further.

Due to the precipitous and rapid nature of the ongoing population decline, we have assigned the northern sea otter in the Aleutian Islands listing a priority of three under our Listing Priority System. Additionally we note that the imminence of the threats underscores the urgent need for more information regarding the cause of the decline in this population.

Request for Information

We request you submit any further information on the northern sea otter as soon as possible or whenever it becomes available. We are seeking the following types of information:

(1) Biological, commercial trade, or other relevant data concerning any threat (or lack thereof) to the northern sea otter;

(2) Reasons why any habitat of this species should or should not be determined to be critical habitat pursuant to section 4 of the Act;

(3) Additional information concerning the range, distribution, and population size of this species; and

(4) Current or planned activities in the subject area and their possible impacts on this species.

Information regarding the range, status, habitat needs, and listing priority assignment for the northern sea otter is available for review by contacting the Service as specified in the ADDRESSES section.

Our practice is to make comments, including names and home addresses of respondents, available for public review during regular business hours. Individual respondents may request that we withhold their home address from the rulemaking record, which we will honor to the extent allowable by law. In certain circumstances, we would withhold from the rulemaking record a respondent's identity, as allowable by law. If you wish for us to withhold your name and/or address, you must state this request prominently at the Start Printed Page 67345beginning of your comment. However, we will not consider anonymous comments. We will make all submissions from organizations or businesses, and from individuals identifying themselves as representatives or officials of organizations or businesses, available for public inspection in their entirety.

References Cited

A complete list of all references cited herein, as well as others, is available upon request from the Marine Mammals Management Office (see ADDRESSES section).

References Cited

Brueggeman, J.J., G.A. Green, R.A. Grotefendt, and D.G. Chapman. 1988. Aerial surveys of sea otters in the northwestern Gulf of Alaska and southeastern Bering Sea. Minerals Management Service and National Oceanic and Atmospheric Administration Final Report. Anchorage, Alaska.

Calkins, D.G., and K.B. Schneider. 1985. The sea otter (Enhydra lutris). Pages 37-45. In: Marine Mammals Species Accounts. J.J. Burns K.J. Frost,and L.F. Lowry (Eds.). Alaska Department of Fish and Game, Technical Bulletin 7.

Estes, J.A. 1990. Growth and equilibrium in sea otter populations. Journal of Animal Ecology 59:385-401.

Estes, J.A., M.T. Tinker, T.M. Williams, and D.F. Doak. 1998. Killer Whale Predation Linking Oceanic and Nearshore Ecosystems. Science 282: 473-476.

Evans, T.J., D.M. Burn, and A.R. DeGange. 1997. Distribution and Relative Abundance of Sea Otters in the Aleutian Archipelago. U.S. Fish & Wildlife Service, Marine Mammals Management Technical Report MMM 97-5. 29 pp.

Johnson, A.M. 1982. Status of Alaska sea otter populations and developing conflicts with fisheries. Trans. 47th North American Wildlife and Natural Resources Conference:293-299.

Kenyon, K. W. 1969. The Sea Otter in the Eastern Pacific Ocean. United States Department of the Interior. North American Fauna, Number 68. 352 pp.

Wilson, D.E., M.A. Bogan, R.L. Brownell, Jr., A.M. Burdin, and M.K. Maminov. 1991. Geographic variation in sea otters, Enhydra lutris. Journal of Mammalogy 72:22-36.


This notice was compiled from materials supplied by staff biologists located in the Service's regional and field offices. The materials were compiled by, Division of Endangered Species (see ADDRESSES section).


The authority for this action is the Endangered Species Act of 1973, as amended, 16 U.S.C. 1531 et seq.

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Dated: November 3, 2000.

David B. Allen,

Regional Director, U. S. Fish and Wildlife Service, Region 7.

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[FR Doc. 00-28796 Filed 11-8-00; 8:45 am]