[Federal Register Volume 59, Number 244 (Wednesday, December 21, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31370]


[[Page Unknown]]

[Federal Register: December 21, 1994]


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Part VI

Department of the Interior
Fish and Wildlife Service

Department of Commerce
National Oceanic and Atmospheric Administration
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Draft Policy Regarding the Recognition of Distinct Vertebrate 
Population Segments Under the Endangered Species Act; Notice
DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

 
Draft Policy Regarding the Recognition of Distinct Vertebrate 
Population Segments Under the Endangered Species Act; Request for 
Public Comment

AGENCIES: Fish and Wildlife Service, Interior; National Marine 
Fisheries Service, Commerce.

ACTION: Notice of draft policy; request for public comment.

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SUMMARY: The Fish and Wildlife Service and the National Marine 
Fisheries Service (Services) propose to adopt a policy to clarify their 
interpretation of the phrase ``distinct population segment of any 
species of vertebrate fish or wildlife'' for the purposes of listing, 
delisting, and reclassifying species under the Endangered Species Act 
of 1973, as amended (16 U.S.C. 1531 et seq.) (Act). The Services seek 
public comment on this draft statement of policy.

DATES: Comments from all interested parties must be received by 
February 21, 1995, in order to be considered in the final decision on 
this draft.

ADDRESSES: Comments and materials concerning this draft policy should 
be sent to Chief, Division of Endangered Species, U.S. Fish and 
Wildlife Service, ARLSQ-452, Washington, D.C. 20240 (telephone 703/358-
2105). Comments and materials received will be available for public 
inspection, by appointment, during normal business hours in Room 452, 
Arlington Square Building, 4401 North Fairfax Drive, Arlington, 
Virginia.

FOR FURTHER INFORMATION CONTACT: Robert G. Ruesink, acting Chief, 
Division of Endangered Species, U.S. Fish and Wildlife Service at the 
above address (703/358-2171), or Russell Bellmer, Chief, Endangered 
Species Division, National Marine Fisheries Service, 1335 East-West 
Highway, Silver Spring, Maryland 20910 (301/713-2322).

SUPPLEMENTARY INFORMATION:

Background

    The Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et 
seq.) (Act) requires the Secretary of the Interior or the Secretary of 
Commerce (depending on jurisdiction) to determine whether species are 
endangered or threatened. In defining ``species,'' the Act as 
originally passed included, ``* * * any subspecies of fish or wildlife 
or plants and any other group of fish or wildlife of the same species 
or smaller taxa in common spatial arrangement that interbreed when 
mature.'' In 1978, the Act was amended so that the definition read ``* 
* * any subspecies of fish or wildlife or plants, and any distinct 
population segment of any species of vertebrate fish or wildlife which 
interbreeds when mature.'' This change restricted application of this 
portion of the definition to vertebrates. The authority to list a 
``species'' as endangered or threatened is thus not restricted to 
species as recognized in formal taxonomic terms, but extends to 
subspecies, and for vertebrate taxa, to distinct population segments.
    Because the Secretary must ``* * * determine whether any species is 
an endangered species or a threatened species'' (section 4(a)(1)), it 
is important that the term ``distinct population segment'' be 
interpreted in a clear and consistent fashion. Furthermore, Congress 
has instructed the Secretary to exercise this authority with regard to 
distinct population segments ``* * * sparingly and only when the 
biological evidence indicates that such action is warranted.'' (Senate 
Report 151, 96th Congress, 1st Session). The Services have used this 
authority relatively rarely; of nearly 300 native vertebrate species 
listed under the Act, only about 20 are given separate status as 
distinct population segments.
    It is important in light of the Act's requirement to use the best 
available scientific information in determining the status of species 
that this interpretation follow sound biological principles. Any 
interpretation adopted should also be aimed at carrying out the 
purposes of the Act (i.e., ``* * * to provide a means whereby the 
ecosystems upon which endangered species and threatened species depend 
may be conserved, to provide a program for the conservation of such 
endangered species and threatened species, and to take such steps as 
may be appropriate to achieve the purposes of the treaties and 
conventions set forth in subsection (a) of this section'' (section 
2(b)).
    Available scientific information provides little specific 
enlightenment in interpreting the phrase ``distinct population 
segment.'' This term is not commonly used in scientific discourse, 
although ``population'' is an important term in a variety of contexts. 
For instance, a population may be circumscribed by a set of 
experimental conditions, or it may approximate an ideal natural group 
of organisms with approximately equal breeding opportunities among its 
members, or it may refer to a loosely bounded, regionally distributed 
collection of organisms. In all cases, the organisms in a population 
are members of a single species.
    The National Marine Fisheries Service (NMFS) has developed a Policy 
on the Definition of Species under the Endangered Species Act (56 FR 
58612-58618; November 20, 1991). The policy applies only to species of 
salmonids native to the Pacific Ocean. Under this policy, a stock of 
Pacific salmon is considered a distinct population segment if it 
represents an evolutionarily significant unit (ESU) of a biological 
species. A stock must satisfy two criteria to be considered an ESU:

    (1) It must be substantially reproductively isolated from other 
conspecific population units; and
    (2) It must represent an important component in the evolutionary 
legacy of the species.

    This document proposes an interpretation of the term ``distinct 
population segment'' for the purposes of listing, delisting, and 
reclassifying vertebrates by the U.S. Fish and Wildlife Service and 
NMFS. It is consistent with the policy on Pacific salmon, but more 
broadly applicable.
    The following principles would, if adopted, guide the Services' 
listing, delisting and reclassification of distinct population segments 
of vertebrate species. Any proposed or final rule affecting status 
determination for a distinct population segment would clearly analyze 
the action in light of these guiding principles.

Policy

    Three elements would be considered in a decision regarding the 
status of a possible distinct population segment as endangered or 
threatened under the Act. These would be applied similarly for addition 
to the lists, reclassification, and removal from the lists:
    1. Discreteness of the population segment in relation to the 
remainder of the species to which it belongs;
    2. The significance of the population segment to the species to 
which it belongs; and
    3. The population segment's conservation status in relation to the 
Act's standards for listing (i.e., is the population segment, when 
treated as if it were a species, endangered or threatened?).
    Discreteness: A population segment of a vertebrate species may be 
considered discrete if it satisfies either one of the following 
criteria:
    1. It is markedly separated from other populations of the same 
taxon as a consequence of physical, physiological, ecological, or 
behavioral factors. Quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation.
    2. It is delimited by international governmental boundaries within 
which differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the Act.
    Significance: If a population segment satisfies one or more of the 
above criteria for discreteness, its biological and ecological 
significance will then be considered in light of Congressional guidance 
that the authority to list distinct population segments be used ``* * * 
sparingly'' while encouraging the conservation of genetic diversity. In 
carrying out this examination, the Services will consider available 
scientific evidence of the discrete population segment's importance to 
the taxon to which it belongs. This consideration may include, but is 
not limited to, the following:
    1. Persistence of the discrete population segment in an ecological 
setting unusual or unique for the taxon,
    2. Evidence that loss of the discrete population segment would 
result in a significant gap in the range of a taxon,
    3. Evidence that the discrete population segment represents the 
only surviving natural occurrence of a taxon that may be more abundant 
as an introduced population outside its historic range, or
    4. Evidence that the discrete population segment differs markedly 
from other populations of the species in its genetic characteristics.
    Because precise circumstances are likely to vary considerably from 
case to case, it is not possible to describe prospectively all the 
classes of information that might bear on the biological and ecological 
importance of a discrete population segment.
    Status: If a population segment is discrete and significant (i.e., 
it is a distinct population segment) its evaluation for endangered or 
threatened status will be based on the Act's definitions of those terms 
and a review of the factors enumerated in section 4(a). It may be 
appropriate to assign different classifications to different distinct 
population segments of the same vertebrate taxon.

Relationship to Other Activities

    The Fish and Wildlife Service's Listing and Recovery Priority 
Guidelines (48 FR 43098; September 21, 1983) generally afford 
``distinct population segments'' the same consideration as subspecies, 
but when a subspecies and a distinct population segment have the same 
numerical priority, the subspecies receives higher priority for 
listing. The Services will continue to generally accord subspecies 
higher listing priority than distinct population segments.
    Any distinct population segment of a vertebrate taxon that was 
listed prior to implementation of this policy will be evaluated on a 
case-by-case basis as recommendations are made to change the listing 
status for that distinct population segment. The appropriate 
application of the policy will also be considered in the 5-year reviews 
of the status of listed species required by section 4(c)(2) of the Act.

Effects of Policy

    This draft policy would, if adopted, guide the evaluation of 
distinct vertebrate population segments for the purposes of listing, 
delisting, and reclassifying under the Act. The only direct effect of 
any policy would be to accept or reject population segments for these 
purposes. More uniform treatment of distinct population segments would 
allow the Services, various other government agencies, private 
individuals and organizations, and other interested or concerned 
parties to better judge and concentrate their efforts toward the 
conservation of biological resources at risk of extinction.
    Listing, delisting, or reclassifying distinct vertebrate population 
segments may allow the Services to protect and conserve species and the 
ecosystems upon which they depend before large-scale decline occurs 
that would necessitate listing a species or subspecies throughout its 
entire range. This would allow protection and recovery of declining 
organisms in a more timely and less costly manner, and on a smaller 
scale than the more costly and extensive efforts that might be needed 
to recover an entire species or subspecies. The Services' ability to 
address local issues (without the need to list, recover, and consult 
rangewide) would result in a more effective program.

Public Comments Solicited

    The Services intend that a final decision on this draft policy on 
distinct population segments of vertebrates take advantage of 
information and recommendations from all interested parties. Therefore, 
comments or suggestions from the public, other concerned governmental 
agencies, the scientific community, industry, or any other interested 
party concerning this draft policy are hereby solicited. Particularly 
sought are comments on the following topics:
    (1) The utility of the draft policy in carrying out the purposes of 
the Act,
    (2) Scientific evidence bearing on the appropriateness of the 
concept of distinct population segments, or
    (3) The relationship between the draft policy and the NMFS policy 
regarding pacific salmon.
    The final decision on this draft policy will take into 
consideration the comments and any additional information received by 
the Services, and such communications may lead to a decision that 
differs from this draft. The Services' decision will be published for 
public information.

Author/Editor

    The editors of this draft policy are Dr. John J. Fay of the Fish 
and Wildlife Service's Division of Endangered Species, 452 ARLSQ, 
Washington, D.C. 20240 (703/358-2105) and Marta Nammack of the National 
Marine Fisheries Service's Endangered Species Division, 1335 East-West 
Highway, Silver Spring, Maryland 20910 (301/713-2322).

Authority

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

    Dated: August 5, 1994.
Mollie H. Beattie,
Director, Fish and Wildlife Service.

    Dated: September 27, 1994
Nancy Foster,
Deputy Assistant Administrator for Fisheries National Marine Fisheries 
Service.
[FR Doc. 94-31370 Filed 12-20-94; 8:45 am]
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