[Federal Register Volume 61, Number 26 (Wednesday, February 7, 1996)]
[Proposed Rules]
[Pages 4710-4713]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-2640]




[[Page 4709]]

_______________________________________________________________________

Part II

Department of the Interior
Fish and Wildlife Service

Department of Commerce
National Oceanic and Atmospheric Administration
_______________________________________________________________________



50 CFR Part 424



Proposed Policy on the Treatment of Intercrosses and Intercross Progeny 
(the Issue of ``Hybridization''); Proposed Rule

  Federal Register / Vol. 61, No. 26 / Wednesday, February 7, 1996 / 
Proposed Rules   

[[Page 4710]]


DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 424

RIN 1018-AC54


Endangered and Threatened Wildlife and Plants; Proposed Policy 
and Proposed Rule on the Treatment of Intercrosses and Intercross 
Progeny (the Issue of ``Hybridization''); Request for Public Comment

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

ACTION: Proposed rule.

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SUMMARY: The Fish and Wildlife Service and the National Marine 
Fisheries Service (Services) propose a policy that will include, within 
the scope of a listing for a specific taxon, ``hybrid'' individuals 
that more closely resemble a parent belonging to a listed species than 
they resemble individuals intermediate between their listed and 
unlisted parents. The Services propose to add to their joint 
regulations the terms ``intercross'' and ``intercross progeny'' and 
indicate the inclusion of intercross individuals within the original 
listing action for the parent entity.
    The proposed policy is intended to allow the Services to aid in the 
recovery of listed species by protecting and conserving intercross 
progeny, eliminating intercross progeny if their presence interferes 
with conservation efforts for a listed species, and fostering 
intercrossing when this would preserve remaining genetic material of a 
listed species. The proposed policy would only sanction these actions 
where recommended in an approved recovery plan, supported in an 
approved genetics management plan (which may or may not be part of an 
approved recovery plan), implemented in a scientifically controlled and 
approved manner, and undertaken to compensate for a loss of genetic 
viability in listed taxa that have been genetically isolated in the 
wild as a result of human activity. Nothing in this regulation would 
excuse compliance with section 10 of the Endangered Species Act.

DATES: Comments on this proposal must be received by April 8, 1996 in 
order to be considered in the final decision on this proposal.

ADDRESSES: Comments and materials concerning this proposal should be 
sent to the Chief, Division of Endangered Species, Mail Stop 452, 
Arlington Square, U.S. Fish and Wildlife Service, Washington, D.C. 
20240. Comments and materials received will be available for public 
inspection, by appointment, during normal business hours in Room 452, 
4401 North Fairfax Drive, Arlington, Virginia 22203.

FOR FURTHER INFORMATION CONTACT: Jamie Rappaport Clark, Chief, Division 
of Endangered Species, at the above Washington, D.C. address, (703/358-
2106).

SUPPLEMENTARY INFORMATION:

Background

    The Endangered Species Act (Act) of 1973, as amended (16 U.S.C. 
1531 et seq.), requires the Services to identify, protect, manage, and 
recover species of plants and animals in danger of extinction. To carry 
out this responsibility, the Services are required to rely on the best 
available scientific and commercial information and to develop sound 
policies to use that information in conserving endangered and 
threatened species and the ecosystems on which they depend. By 
implication, the Act also promotes protection of the genetic resources 
of those species.
    Under the definition of ``species'' found in the Act, the Services 
can apply the protections of the Act to any species or subspecies of 
fish or wildlife or plants, or any distinct population segment of any 
species of vertebrate fish or wildlife that meets the definition of 
endangered or threatened. The Act does not attempt to define 
``species'' in biological terms, and thus allows the term to be applied 
according to the best current biological knowledge and understanding of 
evolution, speciation, and genetics. While the Act does not 
specifically address reproductive isolation, the inclusion of 
subspecies and vertebrate population segments in its definition 
indicated that isolation is not considered absolutely essential for 
listing; however, it does not rule out using reproductive isolation as 
a consideration for listing. In the following discussion, the term 
``species,'' unless qualified as indicating taxonomic species, is used 
in the sense of the Act to include species, subspecies, and distinct 
population segments of vertebrates within a taxonomic species.
    Advances in scientific methodology have altered some traditional 
concepts of taxonomic species and hybridization. Molecular genetic 
studies (e.g., DNA analysis and protein electrophoresis) on both listed 
and unlisted plants and animals indicate that matings and genetic 
exchange between related taxonomic species may be more common events 
than previously believed.
    Examples of introgression (the transfer of genetic material from 
one taxonomic species to another, and its spread among individuals of 
the second species) are found throughout the plant and animal kingdoms. 
In some cases, mating with other species and the resulting 
introgression have apparently been facilitated by a decline in the 
availability of conspecific mates. Given the low densities of many 
populations of rare threatened and endangered species, such 
introgression may be experienced by some listed species.
    As a result of this information, the list of species that may 
contain genetic material traceable to other entities is growing. 
Consequently, questions have been raised as to how the Services can 
best deal with individual organisms and entire entities that may 
contain various levels of ``foreign'' genetic material.
    Previous Service Position. The previous Fish and Wildlife Service 
position, based upon interpretations in a series of opinions by the 
U.S. Department of the Interior, Office of the Solicitor, tended to 
discourage conservation efforts under the authorities of the Act for 
``hybrids'' between taxonomic species or subspecies and the progeny 
produced by such matings. However, advances in biological understanding 
discussed earlier prompted the withdrawal of those opinions on December 
14, 1990. The reasons for this action are summarized in two sentences 
in that withdrawal memorandum (Memorandum from Assistant Solicitor for 
Fish and Wildlife, U.S. Department of the Interior, to Director, U.S. 
Fish and Wildlife Service, dated December 14, 1990)--``New scientific 
information concerning genetic introgression has convinced us that the 
rigid standards set out in those previous opinions should be revisited. 
In our view, the issue of `hybrids' is more properly a biological issue 
than a legal one.'' This notice contains a proposed policy intended to 
replace previous positions held by the Services.
    Intercross and Intercross Progeny Defined. Due to connotations 
attached to the various terms that are in general use for matings 
across taxonomic boundaries and for their products (e.g., cross, 
hybrid, intergrade, and interbreed), the Services propose to use the 
neutral term ``intercross'' for all crosses between individuals of 
different 

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species (taxonomic species, subspecies, and distinct population 
segments of vertebrates). (The use of the term ``intercross'' was 
proposed by Dr. John C. Avise at the May 29-30, 1991, meeting of the 
Captive Breeding Specialist Group, Species Survival Commission, 
International Union for the Conservation of Nature and Natural 
Resources.) The phrase ``intercross progeny'' will be used for 
descendants of intercross events.
    The degree of genetic mixing possible from intercrosses spans a 
broad continuum. At one extreme are cases in which a small number of 
individuals of a species display evidence of introgression. Genetic 
material originating from another entity may remain as evidence of long 
past and/or infrequent matings with that other entity but may have 
little or no effect on the morphology and behavior of the organism. At 
the other extreme are individuals that exhibit morphology that is 
intermediate between that of the parent types, nuclear DNA showing 
strong affinities with both parent types, some degree of functional 
sterility, and/or an inability to ``breed true.'' Somewhere along this 
continuum there may be individuals that possess DNA from past 
intercrosses but in most other ways are representative of a single 
parental stock.
    The Services have identified threatened and endangered species that 
appear to fall at various points along this continuum. Some listed 
species have been found to contain individuals that appear to be 
products of introgression; they appear to harbor mitochondrial DNA 
resulting from introgression, yet there is no morphological or 
behavioral evidence that introgression has occurred. An apparent 
example of this condition is the eastern U.S. population of the gray 
wolf. At the other extreme, the Services have recognized cases in which 
mixing has reached a point where the species intended for conservation 
under the Act no longer exists; remaining genetic material is 
irretrievably mixed with that of another species (e.g., the Amistad 
gambusia (Gambusia amistadensis), which was removed from the list of 
endangered species in 1987).
    While evidence such as similarities in mitochondrial DNA among 
several entities generally supports findings of introgression, such 
data may also be explained by alternate hypotheses. One hypothesis that 
is particularly difficult to rule out involves the retention of common 
genetic markers from common ancestral stock. Some techniques used to 
examine mitochondrial DNA are based on comparisons of fragment lengths 
of DNA obtained from mitochondria. Differences or similarities in 
fragment lengths do not necessarily reflect differences or similarities 
in the genetic codes contained in the fragments.
    As molecular genetic methodology advances, it is anticipated that 
evidence of low levels of introgression and genetic mixing will be 
commonly found among a variety of organisms. In some cases, all 
individuals of a species may be found to display low levels of 
introgression, yet are able to ``breed true.'' The Services find no 
compelling reason to abandon recovery efforts for recognized species 
(those whose members morphologically, ecologically, and behaviorally 
bear close resemblance to one another) due solely to evidence of low-
level present or past introgression, even if apparent introgression 
appears to be geographically widespread.
    Populations of plants and animals that are very small, or have gone 
through a past episode of small population size, may have lost much of 
their previous genetic variability. In extreme cases, which might be 
exemplified by the mainland population of the Torrey pine (Pinus 
torreyana) and the cheetah (Acinonyx jubatus), population genetic 
analyses seem to indicate that there is little genetic variation in the 
remaining population. When genetic variability falls to low levels a 
species may suffer from a diminished capability to respond to 
environmental changes and the increased potential for the adverse 
effects of inbreeding depression (e.g., decreased fertility and/or 
mating, reduced numbers and survival of offspring). These effects may 
be catastrophic for a threatened or endangered species, and actions may 
be necessary to increase genetic variability before the population 
suffers an irreversible decline.
    Proposed Policy for Intercross Progeny. Where intercross progeny 
are produced as a result of a cross between an individual of a listed 
taxon and an individual of a taxon that is not listed, the Services 
believe the responsibility to conserve endangered and threatened 
species under the Act extends to those intercross progeny if (1) the 
progeny share the traits that characterize the taxon of the listed 
parent, and (2) the progeny more closely resemble the listed parent's 
taxon than an entity intermediate between it and the other known or 
suspected non-listed parental stock. The best biological information 
available, including morphometric, ecological, behavioral, genetic, 
phylogenetic, and/or biochemical data, can be used in this 
determination.
    This policy will not prohibit the Services from removing intercross 
progeny from the wild if it is determined that those individuals must 
be removed to enhance the survival or recovery of the listed species. 
The action may be authorized under 50 CFR 17.22, 17.32, 17.62, or 
17.72, or the protection of the Act may be removed by a special rule 
adopted under section 4(d) of the Act for threatened species.
    Intercrosses between subspecies of the same taxonomic species, or 
between members of different vertebrate populations of the same 
taxonomic species or subspecies, are a common, natural, and expected 
occurrence in nature wherever ranges are adjacent or overlap. As with 
other intercrosses, the Services will treat the resulting progeny as 
members of the listed subspecies or population if they share the 
characteristic traits of that entity. This determination will be based 
upon the best biological information available.
    Species of Hybrid Origin. Some taxonomic species have originated 
through the intercrossing of two or more other taxonomic species, but 
have since become stable and self-sustaining biological units. This 
process of speciation by hybridization is well documented among plants 
and also is known among fishes, amphibians, and reptiles. Species that 
are believed to be of hybrid origin would retain or maintain 
eligibility for threatened or endangered status if they have developed 
outside of confinement, are self-sustaining, naturally occurring 
taxonomic species, and meet the criteria for threatened or endangered 
species under the Act.
    Intercross Progeny Produced in Captivity. Unnatural conditions of 
confinement or confining environments resulting from human activities 
may produce behavioral and other anomalies that lead to intercrosses 
that rarely, if ever, occur under ``natural'' conditions. Resulting 
intercross progeny are unlikely to benefit the conservation of their 
listed parent's taxon, and the Services would not generally consider 
such progeny to be members of a species protected under the Act. 
However, this proposed policy would extend protection under the Act to 
intercross progeny produced in captivity, with or without introduction 
to the wild, where the action is (1) recommended by an approved 
recovery plan, (2) supported in an approved genetics management plan 
(which may or may not be part of an approved recovery plan), (3) 
implemented in a scientifically controlled and approved manner, and 

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(4) undertaken to compensate for a loss of genetic viability in listed 
taxa that have been genetically isolated in the wild as a result of 
human activity. Protection under the Act may apply to the individuals 
while they are in confinement, after their release to the wild, or 
during both periods.
    Goals of the Proposed Policy. The primary goal of this proposed 
policy is to provide the Services with the necessary flexibility to 
deal with diverse intercross situations to allow for the protection and 
conservation of intercross progeny at the level of taxonomic species, 
subspecies, and vertebrate populations. A second goal is to give the 
Services the ability to eliminate intercross progeny if their presence 
interferes with conservation efforts for a listed species. Alternately, 
it gives the Services the option to foster intercrossing where required 
for conservation. Because an action that would eliminate or introduce 
genetic material from or to a listed species must be an informed 
decision by experts, the Services will adopt the strongest 
administrative controls over such actions. Prior to implementing any 
action to introduce genetic material, it must be (1) recommended in an 
approved recovery plan, (2) supported in an approved genetics 
management plan (which may or may not be part of an approved recovery 
plan), and (3) undertaken to compensate for a loss of genetic viability 
in listed taxa that have been genetically isolated in the wild as a 
result of human activity. Further, it must be implemented in a 
scientifically controlled and approved manner.
    This proposed rule and policy would provide several conservation 
benefits to species currently listed as threatened or endangered. 
First, it would remove the necessity for the Services to devote 
substantial resources to studies to determine which listed species and 
individuals are genetically ``pure.'' Such studies, if required, would 
need to be extensive; it is not presently possible to accurately 
predict which species and individuals have experienced introgression 
and to what extent. Furthermore, even if such studies were to be 
carried out, the interpretation of the resultant data might be 
ambiguous considering the limits of current technology and incomplete 
understanding of the mechanisms of speciation.
    Second, this proposed policy would acknowledge the Services' 
authority to conduct conservation programs for species that meet the 
listing criteria of Section 4(a)(1) of the Act, even though limited 
introgression may have taken place.
    Third, where determined to be advantageous to recovery and where 
addressed in an approved recovery plan, the proposed policy 
acknowledges the Services' ability to use intercrossing to introduce 
small amounts of new genetic material from a closely related entity 
into a listed species that is genetically depauperate. The progeny of 
such an intercross, if they share characteristic traits of the listed 
species and more closely resemble it than an entity intermediate 
between the parents, would be fully protected by the Act. Such drastic 
steps are expected to be taken only rarely, and it is not the intent of 
this proposed policy to generally encourage the transfer of genetic 
material from one species to another.
    Fourth, by generally excluding (where neither recommended in an 
approved recovery plan nor meeting the other tests set forth in this 
proposed policy) captive-propagated intercross progeny from the 
protection of the Act, the Services retain the ability to readily 
remove from the wild any such organisms that have been released or have 
escaped. Such releases or escapes may threaten existing or future 
recovery efforts by introducing genetic material into a listed species 
in the absence of a comprehensive evaluation of the likely impacts.
    This proposed policy is not expected to affect current listing 
policy, nor will it result in adding species to the list. Several 
species suspected or known to be of hybrid origin (predominantly 
plants) are currently on the endangered and threatened species list 
(e.g., Arizona agave (Agave arizonica) and Mohr's Barbara's buttons 
(Marshallia mohrii)), and protection under the Act of additional 
species of this nature will be consistent with this proposed policy. 
Such species have established themselves as self-sustaining, 
genetically and morphologically, stable units that continue to be 
recognized as taxonomic species by the scientific community. The 
proposed policy would not affect the Services' existing treatment of 
these and similar species.
    Except as noted in the preceding paragraph, this proposed policy 
would not allow the protection of the Act to be extended to a 
``classical hybrid,'' that is, an intermediate organism AB that has 
received half its characteristics from an unlisted parent species A and 
half from a listed parent species B. The offspring AB does not 
sufficiently resemble B to warrant protection under the Act. However, 
all intercross (including backcross) progeny that more closely resemble 
B than they resemble AB would continue to be protected by the Act 
(consistent with past practice). However, where produced under 
conditions of captivity or confinement, such intercross progeny would 
be protected if the intercross was recommended in an approved recovery 
plan and satisfied other requirements set forth in this proposed 
policy.
    The intentional intercrossing of species under confinement and the 
artificial transfer of genetic material from one taxonomic species into 
another (i.e., transgenics) are large and growing endeavors. This 
proposed policy would not include (would not protect) any individual 
organism resulting from these activities when they are performed under 
conditions that confine the progeny of the parents, even temporarily, 
unless the action is recommended in an approved recovery plan and 
satisfies other requirements set forth in this policy. The production 
and commercialization of hybrid organisms for the pet trade, falconry, 
horticulture, agriculture, and aquaculture or sport fishing purposes 
will not otherwise be affected by this proposed policy. Likewise, 
organisms resulting from genetic engineering experiments that use 
genetic material from listed species will not otherwise be covered by 
this proposed policy (although endangered species permits may be 
required to obtain the genetic material), unless such organisms are 
produced for the purpose of recovery of the listed species in 
accordance with an approved recovery plan. Private citizens or 
organizations that possess plants or animals of such origin would not 
normally be required to obtain additional Federal permits as a result 
of this proposed policy.
    This proposed policy is intended to assist the Services in 
conserving endangered and threatened species and their unique genetic 
complements even if all individuals of a listed species have small 
amounts of genetic material from another species. However, this 
proposed policy is not intended to provide general support for, or 
preclude the establishment of, ``ecologically equivalent forms'' in 
habitats formerly occupied by threatened or endangered species. 
Ecologically equivalent forms are taxonomic species, subspecies, or 
populations that are used as replacements for extirpated or extinct 
species in order to maintain an apparently stable and complete plant 
and animal community.
    Juvenile specimens of intercrosses of a listed species and an 
unlisted species may be indistinguishable from the unlisted species 
using traditional field procedures. In such a case, it would be 
impossible under field conditions to properly classify the juvenile 
stage of a possible intercross. For this reason, all 

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individuals that resemble a protected species should be protected until 
they have reached a life stage at which they can be distinguished from 
the listed species. The law enforcement implications of this policy are 
that because of similarity of appearance, taking of these individuals 
would be prohibited since they cannot be readily distinguished in the 
field from a listed species.

Public Comments Solicited

    The Services intend that any final action resulting from this 
proposal will be as accurate and as effective as possible. Therefore, 
comments or suggestions from the public, other concerned governmental 
agencies, the scientific community, industry, or any other interested 
party concerning this proposed rule are hereby solicited.

Regulatory Flexibility Act and Executive Order 12866

    The Department of the Interior has determined that the proposed 
revisions to part 424 will not constitute a significant rule under 
Executive Order 12866 and certify that these changes will not have a 
significant economic effect on a substantial number of small entities 
under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.). Based on 
the information discussed in this proposed rule, it is not expected 
that significant economic impacts would result. Also, no direct costs, 
enforcement costs, information collection, or record keeping 
requirements are imposed on small entities by this proposed rule. 
Further, the proposed rule contains no information collection or 
record-keeping requirements as defined by the Paperwork Reduction Act 
of 1995.

National Environmental Policy Act of 1969 (NEPA)

    The Services believe that this action may be categorically excluded 
under the Services' NEPA procedures. (See 516 DM 2 Appendix I 
Categorical Exclusion 1.10.) After further review, the Services will 
decide whether an Environmental Assessment must be prepared.

    Editors: The editors of this proposal are William Kramer of the 
Fish and Wildlife Service's Division of Endangered Species, 452 
ARLSQ, Washington, D.C. 20240 (703/358-2106); and Marta Nammack, 
Endangered Species Division, National Marine Fisheries Service, 1315 
East-West Highway, Silver Spring, Maryland 20910 (301/713-2322).

List of Subjects in 50 CFR Part 424

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, and Transportation.

Proposed Regulation Promulgation

    Accordingly, the Services hereby propose to amend part 424, 
subchapter A of chapter IV, title 50 of the Code of Federal 
Regulations, as set forth below:

PART 424--[AMENDED]

    1. The authority citation for part 424 continues to read as 
follows:

    Authority: Pub. L. 93-205, 87 Stat. 884; Pub. L. 95-632, 92 
Stat. 3751; Pub. L. 96-159, 93 Stat. 1225; Pub. L. 97-304, 96 Stat. 
1411 (16 U.S.C. 1531 et seq.).

    2. It is proposed that Sec. 424.02 be amended by redesignating 
paragraphs (f) through (n) as paragraphs (h) through (p) respectively, 
and adding new paragraphs (f) and (g) to read as follows:


Sec. 424.02.  Definitions.

* * * * *
    (f) Intercross means any mating, fertilization, or other means of 
exchange of genetic material between different species, subspecies, or 
distinct vertebrate population segments within a taxonomic species.
    (g) Intercross progeny means any and all offspring and descendants 
that are the product of an intercross.
* * * * *
    3. It is proposed that a new Sec. 424.03 be added to subpart A to 
read as follows:


Sec. 424.03  Intercross and intercross progeny.

    (a) Unless specified otherwise and indicated by an annotation in 
the ``Scientific name'' column, any species listed as endangered or 
threatened pursuant to the Act will include all individuals that, 
considering the sum of available morphological, behavioral, ecological, 
biochemical, genetic, and other relevant data, more closely resemble 
such listed species than they resemble an intermediate between their 
listed and unlisted parents.
    (b) Individuals that are the products of intercrosses that occurred 
under conditions of confinement will be excepted from the inclusion in 
paragraph (a) of this section unless such production is:
    (1) Recommended in an approved recovery plan for a listed parent 
species;
    (2) Supported in an approved genetics management plan (which may or 
may not be part of an approved recovery plan);
    (3) Implemented in a scientifically controlled and approved manner; 
and
    (4) Undertaken to compensate for a loss of genetic viability in 
listed taxa that have been genetically isolated in the wild as a result 
of human activity.

    Dated: February 1, 1996.
George T. Frampton, Jr.,
Assistant Secretary for Fish and Wildlife and Parks, Department of the 
Interior.

    Dated: February 2, 1996.
Nancy Foster,
Deputy Assistant Administrator for Fisheries, National Marine Fisheries 
Service.
[FR Doc. 96-2640 Filed 2-6-96; 8:45 am]
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