Proposed Rule2024-27127
Endangered and Threatened Wildlife and Plants; Threatened Species Status With Section 4(d) Rule for Pecos Pupfish and Designation of Critical Habitat
Primary source
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Published
November 22, 2024
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), propose to list the Pecos pupfish (Cyprinodon pecosensis), a fish species from the Pecos River Basin of New Mexico and Texas, as a threatened species and designate critical habitat under the Endangered Species Act of 1973, as amended (Act). This determination also serves as our 12-month finding on a petition to list the Pecos pupfish. After a review of the best available scientific and commercial information, we find that listing the species is warranted. Accordingly, we propose to list the Pecos pupfish as a threatened species with a rule issued under section 4(d) of the Act ("4(d) rule"). If we finalize this rule as proposed, the Pecos pupfish would be added to the List of Endangered and Threatened Wildlife and the Act's protections would be extended to the species. We also propose to designate critical habitat for the Pecos pupfish under the Act. In total, 136.12 river miles (219.06 river kilometers) and 26,555.54 acres (10,746.64 hectares) in Chaves and Eddy Counties, New Mexico, and Culberson and Reeves Counties, Texas, fall within the boundaries of the proposed critical habitat designation. We also announce the availability of an economic analysis of the proposed designation of critical habitat for Pecos pupfish.
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[Federal Register Volume 89, Number 226 (Friday, November 22, 2024)]
[Proposed Rules]
[Pages 92744-92785]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-27127]
[[Page 92743]]
Vol. 89
Friday,
No. 226
November 22, 2024
Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Threatened Species
Status With Section 4(d) Rule for Pecos Pupfish and Designation of
Critical Habitat; Proposed Rule
Federal Register / Vol. 89 , No. 226 / Friday, November 22, 2024 /
Proposed Rules
[[Page 92744]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R2-ES-2024-0143; FXES1111090FEDR-256-FF09E21000]
RIN 1018-BH76
Endangered and Threatened Wildlife and Plants; Threatened Species
Status With Section 4(d) Rule for Pecos Pupfish and Designation of
Critical Habitat
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
list the Pecos pupfish (Cyprinodon pecosensis), a fish species from the
Pecos River Basin of New Mexico and Texas, as a threatened species and
designate critical habitat under the Endangered Species Act of 1973, as
amended (Act). This determination also serves as our 12-month finding
on a petition to list the Pecos pupfish. After a review of the best
available scientific and commercial information, we find that listing
the species is warranted. Accordingly, we propose to list the Pecos
pupfish as a threatened species with a rule issued under section 4(d)
of the Act (``4(d) rule''). If we finalize this rule as proposed, the
Pecos pupfish would be added to the List of Endangered and Threatened
Wildlife and the Act's protections would be extended to the species. We
also propose to designate critical habitat for the Pecos pupfish under
the Act. In total, 136.12 river miles (219.06 river kilometers) and
26,555.54 acres (10,746.64 hectares) in Chaves and Eddy Counties, New
Mexico, and Culberson and Reeves Counties, Texas, fall within the
boundaries of the proposed critical habitat designation. We also
announce the availability of an economic analysis of the proposed
designation of critical habitat for Pecos pupfish.
DATES: We will accept comments received or postmarked on or before
January 21, 2025. We must receive requests for a public hearing, in
writing, at the address shown in FOR FURTHER INFORMATION CONTACT, by
January 6, 2025.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: <a href="https://www.regulations.gov">https://www.regulations.gov</a>. In the Search box, enter FWS-R2-ES-2024-0143,
which is the docket number for this rulemaking. Then, click on the
Search button. On the resulting page, in the panel on the left side of
the screen, under the Document Type heading, check the Proposed Rule
box to locate this document. You may submit a comment by clicking on
``Comment.'' Comments submitted electronically using the Federal
eRulemaking Portal must be received by 11:59 p.m. eastern time on the
closing date.
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R2-ES-2024-0143, U.S. Fish and Wildlife Service,
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on <a href="https://www.regulations.gov">https://www.regulations.gov</a>. This
generally means that we will post any personal information you provide
us (see Information Requested, below, for more information).
Availability of supporting materials: Supporting materials, such as
the species status assessment report, are available on the Service's
website at <a href="https://www.fws.gov/office/new-mexico-ecological-services">https://www.fws.gov/office/new-mexico-ecological-services</a>,
at <a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-R2-ES-2024-0143, or
both. If we finalize the critical habitat designation, we will make the
coordinates or plot points or both from which the maps are generated
available at <a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-R2-ES-2024-
0143 and on the Service's website at <a href="https://www.fws.gov/office/new-mexico-ecological-services">https://www.fws.gov/office/new-mexico-ecological-services</a>.
FOR FURTHER INFORMATION CONTACT: Shawn Sartorius, Field Supervisor,
U.S. Fish and Wildlife Service, New Mexico Ecological Services Field
Office, 2105 Osuna NE, Albuquerque, NM 87113; telephone 505-697-7606.
Individuals in the United States who are deaf, deafblind, hard of
hearing, or have a speech disability may dial 711 (TTY, TDD, or
TeleBraille) to access telecommunications relay services. Individuals
outside the United States should use the relay services offered within
their country to make international calls to the point-of-contact in
the United States. Please see Docket No. FWS-R2-ES-2024-0143 on <a href="https://www.regulations.gov">https://www.regulations.gov</a> for a document that summarizes this proposed rule.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species warrants
listing if it meets the definition of an endangered species (in danger
of extinction throughout all or a significant portion of its range) or
a threatened species (likely to become an endangered species within the
foreseeable future throughout all or a significant portion of its
range). If we determine that a species warrants listing, we must list
the species promptly and designate the species' critical habitat to the
maximum extent prudent and determinable. We have determined that the
Pecos pupfish meets the definition of a threatened species; therefore,
we are proposing to list it as such, and we are proposing a designation
of its critical habitat. Both listing a species as an endangered or
threatened species and making a critical habitat designation can be
completed only by issuing a rule through the Administrative Procedure
Act rulemaking process (5 U.S.C. 551 et seq.).
What this document does. We propose to list the Pecos as a
threatened species with a rule issued under section 4(d) of the Act,
and we propose the designation of critical habitat for the species
The basis for our action. Under the Act, we may determine that a
species is an endangered or threatened species because of any of five
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or manmade factors affecting its
continued existence. We have determined that Pecos pupfish meets the
definition of a threatened species due to the following threats: (1)
introgression of the sheepshead minnow (Cyprinodon variegatus) (Factor
E), (2) the loss and decline of surface and ground waters (Factor A),
(3) degradation of water quality (Factor A), and (4) habitat loss and
fragmentation (Factor A), all of which are exacerbated by the ongoing
and expected effects of climate change (Factor E).
Section 4(a)(3) of the Act requires that the Secretary of the
Interior (Secretary), to the maximum extent prudent and determinable,
concurrently with listing, designate critical habitat for the species.
Section 3(5)(A) of the Act defines critical habitat as (i) the specific
areas within the geographical area occupied by the species, at the time
it is listed, on which are found those physical or biological features
(I) essential to the conservation of the species and (II) which may
require special management considerations or protections; and (ii)
specific areas outside the geographical
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area occupied by the species at the time it is listed, upon a
determination by the Secretary that such areas are essential for the
conservation of the species. Section 4(b)(2) of the Act states that the
Secretary must make the designation on the basis of the best scientific
data available and after taking into consideration the economic impact,
the impact on national security, and any other relevant impacts of
specifying any particular area as critical habitat.
Information Requested
We intend that any final action resulting from this proposed rule
will be based on the best scientific and commercial data available and
be as accurate and as effective as possible. Therefore, we request
comments or information from other governmental agencies, Native
American Tribes, the scientific community, industry, or any other
interested parties concerning this proposed rule. We particularly seek
comments concerning:
(1) The species' biology, range, and population trends, including:
(a) Biological or ecological requirements of the species, including
habitat requirements for feeding, breeding, and sheltering;
(b) Genetics and taxonomy;
(c) Historical and current range, including distribution patterns
and the locations of any additional populations of this species;
(d) Historical and current population levels, and current and
projected trends; and
(e) Past and ongoing conservation measures for the species, its
habitat, or both.
(2) Threats and conservation actions affecting the species,
including:
(a) Factors that may be affecting the continued existence of the
species, which may include habitat modification or destruction,
overutilization, disease, predation, the inadequacy of existing
regulatory mechanisms, or other natural or manmade factors.
(b) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to this species.
(c) Existing regulations or conservation actions that may be
addressing threats to this species.
(3) Additional information concerning the historical and current
status of this species.
(4) Information to assist with applying or issuing protective
regulations under section 4(d) of the Act that may be necessary and
advisable to provide for the conservation of the Pecos pupfish. In
particular, information concerning:
(a) The extent to which we should include any of the Act's section
9 prohibitions in the proposed 4(d) rule; or
(b) Whether we should consider any additional or different
exceptions from the prohibitions in the proposed 4(d) rule.
(5) Specific information related to critical habitat, such as:
(a) The amount and distribution of Pecos pupfish habitat;
(b) Any additional areas occurring within the range of the species,
Chaves and Eddy Counties, New Mexico, and Culberson and Reeves
Counties, Texas, that should be included in the designation because
they (i) are occupied at the time of listing and contain the physical
or biological features that are essential to the conservation of the
species and that may require special management considerations or
protection, or (ii) are unoccupied at the time of listing and are
essential for the conservation of the species; and
(c) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of climate change.
(6) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(7) Any probable economic, national security, or other relevant
impacts of designating any area that may be included in the final
designation, and the related benefits of including or excluding
specific areas.
(8) Information on the extent to which the description of probable
economic impacts in the economic analysis is a reasonable estimate of
the likely economic impacts and the description of the environmental
impacts in the environmental assessment is complete and accurate and
any additional information regarding probable economic impacts that we
should consider.
(9) Whether any specific areas we are proposing for critical
habitat designation should be considered for exclusion under section
4(b)(2) of the Act, and whether the benefits of potentially excluding
any specific area outweigh the benefits of including that area, in
particular for those covered by the Pecos Pupfish Conservation
Agreement (see more details in Conservation Efforts and Regulatory
Mechanisms below). If you think we should exclude any additional areas,
please provide information supporting a benefit of exclusion.
(10) Whether we could improve or modify our approach to designating
critical habitat in any way to provide for greater public participation
and understanding, or to better accommodate public concerns and
comments.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, do not provide substantial
information necessary to support a determination. Section 4(b)(1)(A) of
the Act directs that determinations as to whether any species is an
endangered or a threatened species must be made solely on the basis of
the best scientific and commercial data available, and section 4(b)(2)
of the Act directs that the Secretary shall designate critical habitat
on the basis of the best scientific data available.
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via <a href="https://www.regulations.gov">https://www.regulations.gov</a>, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Our final determination may differ from this proposal because we
will consider all comments we receive during the comment period as well
as any information that may become available after this proposal. Based
on the new information we receive (and, if relevant, any comments on
that new information), we may conclude that the species is endangered
instead of threatened, or we may conclude that the species does not
warrant listing as either an endangered species or a threatened
species. For critical habitat, our final designation may not include
all areas proposed, may include some additional areas that meet the
definition of critical habitat, or may exclude some areas if we find
the benefits of exclusion outweigh
[[Page 92746]]
the benefits of inclusion and exclusion will not result in the
extinction of the species. In addition, we may change the parameters of
the prohibitions or the exceptions to those prohibitions in the
protective regulations under section 4(d) of the Act if we conclude it
is appropriate in light of comments and new information received. For
example, we may expand the prohibitions if we conclude that the
protective regulation as a whole, including those additional
prohibitions, is necessary and advisable to provide for the
conservation of the species. Conversely, we may establish additional or
different exceptions to the prohibitions in the final rule if we
conclude that the activities would facilitate or are compatible with
the conservation and recovery of the species. In our final rule, we
will clearly explain our rationale and the basis for our final
decision, including why we made changes, if any, that differ from this
proposal.
Public Hearing
Section 4(b)(5) of the Act provides for a public hearing on this
proposal, if requested. Requests must be received by the date specified
in DATES. Such requests must be sent to the address shown in FOR
FURTHER INFORMATION CONTACT. We will schedule a public hearing on this
proposal, if requested, and announce the date, time, and place of the
hearing, as well as how to obtain reasonable accommodations, in the
Federal Register and local newspapers at least 15 days before the
hearing. We may hold the public hearing in person or virtually via
webinar. We will announce any public hearing on our website, in
addition to the Federal Register. The use of virtual public hearings is
consistent with our regulations at 50 CFR 424.16(c)(3).
Previous Federal Actions
We identified the Pecos pupfish as a Category 2 candidate in both
the December 30, 1982, Review of Vertebrate Wildlife, Notice of Review
(47 FR 58454); and the September 18, 1985, Review of Vertebrate
Wildlife, Notice of Review (50 FR 37958). Category 2 candidates were
those species for which the Service had information that proposed
listing was possibly appropriate, but conclusive data on biological
vulnerability and threats were not available to support a proposed rule
at the time. This situation changed when the Pecos pupfish was
identified as a Category 1 candidate in the January 6, 1989, Animal
Notice of Review (54 FR 554) and in the November 21, 1991, Animal
Notice of Review (56 FR 58804). Category 1 candidates were those
species for which the Service had on file sufficient information to
support issuance of proposed listing rules. In the February 28, 1996,
Candidate Notice of Review (61 FR 7596), we discontinued the
designation of multiple categories of candidates, and only former
Category 1 species are now recognized as candidates for listing
purposes. The Pecos pupfish remained a candidate species in the 1996
Notice of Review and also in the September 19, 1997, Notice of Review
(62 FR 49398).
The Pecos pupfish was proposed for listing as an endangered species
without critical habitat on January 30, 1998 (63 FR 4608). Within the
ensuing year between the proposal of the species for listing and the
required final determination, a conservation agreement was developed.
The conservation agreement was cited in the March 17, 2000, withdrawal
of the proposed rule to list (65 FR 14513) as sufficient to ensure the
viability of the Pecos pupfish.
On June 18, 2007, we were petitioned to list the Pecos pupfish as
an endangered species as part of a multi-species petition to list 475
species in the Service's Southwest Region by WildEarth Guardians (WEG,
formerly Forest Guardians). On December 16, 2009, we issued a positive
90-day finding that the petition presented information indicating that
the listing of the Pecos pupfish may be warranted (74 FR 66866) and
initiated a status review. Per a court-approved settlement agreement,
we agreed to send a 12-month petition finding for the Pecos pupfish to
the Federal Register by December 1, 2024.
Peer Review
A species status assessment (SSA) team prepared an SSA report for
the Pecos pupfish. The SSA team was composed of Service biologists, in
consultation with other species experts. The SSA report represents a
compilation of the best scientific and commercial data available
concerning the status of the species, including the impacts of past,
present, and future factors (both negative and beneficial) affecting
the species.
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), and in our August 22,
2016, memorandum updating and clarifying the role of peer review in
listing and recovery actions under the Act (<a href="https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf">https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf</a>), we solicited independent scientific review of the information
contained in the Pecos pupfish SSA report. We sent the SSA report to
four independent peer reviewers and received four responses. Results of
this structured peer review process can be found at <a href="https://www.regulations.gov">https://www.regulations.gov</a> and <a href="https://www.fws.gov/office/new-mexico-ecological-services">https://www.fws.gov/office/new-mexico-ecological-services</a>. In preparing this proposed rule, we incorporated
the results of these reviews, as appropriate, into the SSA report,
which is the foundation for this proposed rule.
Summary of Peer Reviewer Comments
As discussed in Peer Review above, we received comments from four
peer reviewers on the draft SSA report. We reviewed all comments we
received from the peer reviewers for substantive issues and new
information regarding the contents of the SSA report. The peer
reviewers generally concurred with our methods and conclusions and
provided additional information, clarifications, and suggestions,
including clarifications in terminology, additional literature on
habitat fragmentation, discussions of severity of threats, and other
editorial suggestions. Otherwise, no substantive changes to our
analysis and conclusions within the SSA report were deemed necessary,
and peer reviewer comments are addressed in version 1.2 of the SSA
report (Service 2024, entire).
I. Proposed Listing Determination
Background
A thorough review of the taxonomy, life history, and ecology of the
Pecos pupfish is presented in the SSA report (version 1.2; Service
2024, pp. 1-21). The following sections are a synopsis of that
information.
The Pecos pupfish is a small, deep-bodied (28 to 46 millimeter (mm)
(1.1 to 1.8 inch (in.)), freshwater fish from the Pecos River Basin of
New Mexico and Texas. It occurs in a variety of aquatic environments
including wetlands, sinkholes, waterfowl impoundments, streams, springs
and the Pecos River mainstem. The species historically inhabited the
upper, middle, and lower Pecos River from just above Bitter Lake
National Wildlife Refuge (NWR), Chaves County, NM, in the north, to
south of the mouth of Independence Creek, in Crockett and Terrell
Counties, TX, in the south. The Pecos pupfish is a member of the
Cyprinodontidae family (pupfish and killifish), a group that includes 9
genera, 115 species, and 8 subspecies (ITIS 2023, entire). It is
recognized as a valid taxon by the American Fisheries Society, and the
Service accepts this taxonomy.
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The Pecos pupfish varies in body color from gray to brown to
iridescent blue. Pecos pupfish vary phenotypically amongst isolated
habitat types, which may be advantageous for adapting to different food
availability, dissolved oxygen availability, and salinity levels
(Collyer et al. 2015, entire; Xu 2017, p. 22). Pecos pupfish are
opportunistic omnivores; their diet is primarily composed of a diatom-
detritus mixture, but may also include animal material, filamentous
algae, macrophytes, sand, and seeds (Davis 1981, p. 536).
Pupfish are a euryhaline group of fish and are able to withstand
conditions such as elevated salinity, higher water temperatures, and
lower dissolved oxygen, that many other fish cannot tolerate (Kodric-
Brown 1975, pp. 3, 6). The Pecos pupfish occurs in a variety of aquatic
environments including wetlands, sinkholes, waterfowl impoundments,
streams, springs, and the Pecos River mainstem (Hoagstrom and Brooks
1999, pp. 14-16; Collyer et al. 2015, p. 182). Pecos pupfish prefer
environments with little to no water flow, and, in areas with flows,
they typically occupy pools and shallow runs and riffles (Hoagstrom and
Brooks 1999, pp. 36, 45). Within their occupied habitat, Pecos pupfish
require a diverse set of microscale habitat conditions. A variety of
underwater features such as crevices, boulders, large rocks, scattered
pebbles, and aquatic plants provide topographic diversity throughout
the range of the Pecos pupfish (Kodric-Brown 1975, p. 35; 1977, pp.
750-751, 753-756, and 761-762).
Pecos pupfish are sexually mature at 20 mm (0.79 in), within a few
months of hatching (Kodric-Brown 1983, p. 128). Female Pecos pupfish
lay an average of 10 eggs per day that adhere to spawning substrate,
such as vegetation or rocks (Kodric-Brown 1977, pp. 751, 761-762, 764;
(Garrett 1982, pp. 360, 363; Farrington and Brandenburg 2003, p. 1).
Spawning occurs May through September, peaking in late June through
July when water temperatures consistently exceed 30 degrees Celsius
([deg]C) (86 degrees Fahrenheit ([deg]F)) in shallow waters less than 2
meters (m) (6.56 feet (ft)) deep, and in areas with a variety of silt-
free underwater features such as crevices, boulders, large rocks,
scattered pebbles, and aquatic plants (Kodric-Brown 1975, p. 35; 1977,
pp. 750-751, 753-756, and 761-762). Pecos pupfish generally live for 1
year but can live an average of 2.5 years in captivity (Kodric-Brown
1977, p. 752m 765; Doege 2023, entire).
Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species.
The Act defines an ``endangered species'' as a species that is in
danger of extinction throughout all or a significant portion of its
range, and a ``threatened species'' as a species that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether any species is an endangered species or a threatened
species because of any of the following factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself.
However, the mere identification of any threat(s) does not
necessarily mean that the species meets the statutory definition of an
``endangered species'' or a ``threatened species.'' In determining
whether a species meets either definition, we must evaluate all
identified threats by considering the species' expected response and
the effects of the threats--in light of those actions and conditions
that will ameliorate the threats--on an individual, population, and
species level. We evaluate each threat and its expected effects on the
species, then analyze the cumulative effect of all of the threats on
the species as a whole. We also consider the cumulative effect of the
threats in light of those actions and conditions that will have
positive effects on the species, such as any existing regulatory
mechanisms or conservation efforts. The Secretary determines whether
the species meets the definition of an ``endangered species'' or a
``threatened species'' only after conducting this cumulative analysis
and describing the expected effect on the species.
The Act does not define the term ``foreseeable future,'' which
appears in the statutory definition of ``threatened species.'' Our
implementing regulations at 50 CFR 424.11(d) set forth a framework for
evaluating the foreseeable future on a case-by-case basis, which is
further described in the 2009 Memorandum Opinion on the foreseeable
future from the Department of the Interior (DOI), Office of the
Solicitor (M-37021, January 16, 2009; ``M-Opinion,'' available online
at <a href="https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf">https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf</a>). The foreseeable future extends as far into the future as
the U.S. Fish and Wildlife Service and National Marine Fisheries
Service (hereafter, the Services) can make reasonably reliable
predictions about the threats to the species and the species' responses
to those threats. We need not identify the foreseeable future in terms
of a specific period of time. We will describe the foreseeable future
on a case-by-case basis, using the best available data and taking into
account considerations such as the species' life-history
characteristics, threat-projection timeframes, and environmental
variability. In other words, the foreseeable future is the period of
time over which we can make reasonably reliable predictions.
``Reliable'' does not mean ``certain''; it means sufficient to provide
a reasonable degree of confidence in the prediction, in light of the
conservation purposes of the Act.
Analytical Framework
The SSA report documents the results of our comprehensive
biological review of the best scientific and commercial data regarding
the status of the species, including an assessment of the potential
threats to the species. The SSA report does not represent our decision
on
[[Page 92748]]
whether the species should be proposed for listing as an endangered or
threatened species under the Act. However, it does provide the
scientific basis that informs our regulatory decisions, which involve
the further application of standards within the Act and its
implementing regulations and policies.
To assess Pecos pupfish viability, we used the three conservation
biology principles of resiliency, redundancy, and representation
(Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency is the
ability of the species to withstand environmental and demographic
stochasticity (for example, wet or dry, warm or cold years); redundancy
is the ability of the species to withstand catastrophic events (for
example, droughts, large pollution events); and representation is the
ability of the species to adapt to both near-term and long-term changes
in its physical and biological environment (for example, climate
conditions, pathogens). In general, species viability will increase
with increases in resiliency, redundancy, and representation (Smith et
al. 2018, p. 306). Using these principles, we identified the species'
ecological requirements for survival and reproduction at the
individual, population, and species levels, and described the
beneficial and risk factors influencing the species' viability.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical
and current condition of the species' demographics and habitat
characteristics, including an explanation of how the species arrived at
its current condition. The final stage of the SSA involved making
predictions about the species' responses to positive and negative
environmental and anthropogenic influences. Throughout all of these
stages, we used the best available information to characterize
viability as the ability of a species to sustain populations in the
wild over time, which we then used to inform our regulatory decision.
The following is a summary of the key results and conclusions from
the SSA report; the full SSA report can be found at Docket No. FWS-R2-
ES-2024-0143 on <a href="https://www.regulations.gov">https://www.regulations.gov</a> and at <a href="https://www.fws.gov/office/new-mexico-ecological-services">https://www.fws.gov/office/new-mexico-ecological-services</a>.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of the
species, its resources, and the threats that influence the species'
current and future condition, in order to assess the species' overall
viability and the risks to that viability.
We analyze these factors both individually and cumulatively to
determine the current condition of the species and project the future
condition of the species under both plausible future scenarios at mid-
and late-century.
Species Needs
For the Pecos pupfish to have sufficient resiliency, redundancy,
and representation, individuals need suitable habitat that supports
essential life functions at all life stages (see table 1, below). Based
upon the best available scientific and commercial information, and
acknowledging existing ecological uncertainties, the Pecos pupfish
needs include: (1) adequate population abundance, (2) sufficient water
quantity, (3) suitable water quality, and (4) habitat diversity.
Table 1--Summary of Pecos Pupfish Individual Environmental Needs by Life
Stage
------------------------------------------------------------------------
Life stage Resource/environmental needs
------------------------------------------------------------------------
Spawning adult......................... <bullet> Warm water
temperatures between May and
September.
<bullet> Suitable oviposition
sites (such as crevices,
boulders, pebbles, scattered
rocks, and subsurface
vegetation mats).
<bullet> Shallow water less
than 2 m (6.56 ft) deep.
Egg.................................... <bullet> Salinities greater
than 35,000 milligrams/liter
(mg/L).
Juvenile/non-breeding adults........... <bullet> Adequate abundance of
food (algae, insects,
vegetation, etc.).
Overwintering adults and juveniles..... <bullet> Dense vegetation.
<bullet> Deeper water.
All.................................... <bullet> Hydrologic conditions
conducive to survival
(sufficient water levels,
sufficient water temperature,
etc.).
------------------------------------------------------------------------
Adequate Population Abundance
Two demographic factors, adult survival and fecundity, influence
Pecos pupfish population trends and stability (Kodric-Brown and
Mazzolini 1992, p. 175; Echelle and Connor 1989, p. 725; Echelle et al.
2003b, entire). The best available information indicates that Pecos
pupfish can live up to 1 year in the wild and 2.5 years in captivity;
however, we have no data on egg and juvenile survival (Kodric-Brown
1977, pp. 756-758; Garrett et al. 2002, p. 366; Doege 2023, entire).
Data collected annually as part of a 23-year monitoring effort for the
Pecos Pupfish Conservation Agreement (see more details in Conservation
Efforts and Regulatory Mechanisms below) have consistently detected
Pecos pupfish; however, there are typically significant year-to-year
variations in the number of fish caught at each sampling location (Hatt
2021, p. 6). To be resilient, populations of Pecos pupfish need to have
enough individuals (abundance) to withstand stochastic events.
Additionally, populations need to exist in locations where
environmental conditions provide suitable habitat and water quality
such that adequate numbers of individuals can be supported, and where
there is an absence of sheepshead minnow. Without all these factors, a
population has an increased likelihood for localized extirpation.
The sheepshead minnow, once confined to shallow, brackish, coastal
waters of the Gulf and Atlantic coasts of the continental United
States, was introduced via a bait-bucket transfer into Red Bluff
Reservoir near Pecos, Texas, in the early 1980s (Echelle and Connor
1989, p. 717; Childs et al. 1996, p. 2020;). By the late 1980s, Pecos
pupfish were extirpated from this area and replaced by the Pecos
pupfish x sheepshead minnow hybrid (Connor 1987, p. 2; Echelle and
Connor 1989, pp. 717-720). In 1997, Pecos pupfish x sheepshead minnow
hybrids were discovered in the Pecos River at Loving Crossing, Eddy
County, NM (Echelle et al. 1997, p. 338; Echelle and Echelle 2007, p.
4). Records from 2016 and 2017 indicate that sheepshead minnow likely
occur as far north as the Brantley Dam, Eddy County, NM, and that non-
introgressed Pecos pupfish are extirpated from the Pecos River below
[[Page 92749]]
Brantley Reservoir, with the exception of the Salt Creek Texas (TX)
population (Davenport 2023a, entire).
Sufficient Water Quantity
Pecos pupfish depend on sufficient water quantity to complete all
stages of their lifecycle. While Pecos pupfish persist in shallow
habitats less than 1 m (3.3 ft) deep (Salt Creek, NM), they may need
deeper water to provide thermal refugia and winter habitat (Kodric-
Brown 1977, p. 755). Sufficient water quantity is also necessary
throughout the year for breeding and adult survival (Kodric-Brown 1977,
p. 754; Hoagstrom et al. 2015, p. 14). It is surmised that water
quantity changes in small, ephemeral streams have led to Pecos pupfish
mortality events in both Bitter Creek and Salt Creek (NM) (Davenport
2023a and 2023b, entire; Jacobsen 2023, entire; Hoagstrom 2009, p. 28).
Water quantity for the Pecos pupfish is influenced by a variety of
factors depending on the specific aquatic environment of a particular
Pecos pupfish site or population. Sinkhole environments in the Pecos
Basin are largely spring-fed systems derived from the San Andres
artesian aquifer (Land 2003, p. 230). Similarly, permanent water in the
Bitter Creek and Salt Creek (NM) likely originates from spring flow
from the San Andres aquifer (Land and Huff 2009, p. 1). Salt Creek (TX)
likely is supported by spring flows from the Toyah Aquifer, though no
direct modeling has been done on this particular stream (LaFave 1987,
p. 34). These streams also hold water during precipitation events.
Water in Bitter Lake NWR is managed through a series of constructed
impoundments and water conveyance structures. The Bureau of Land
Management (BLM) Overflow Wetlands are supported by outflows of water
from Lea Lake, a sinkhole in Bottomless Lakes State Park, as well as
precipitation. Finally, water in the Pecos River is managed by the
Bureau of Reclamation (BOR) for water deliveries, environmental flows,
and fulfilling obligations under the 1948 Pecos River Compact
(Llewellyn et al. 2021, pp. 39-42).
Karst aquifer systems, like that found in Bitter Lake NWR, may
affect sinkhole systems, as groundwater pumping may tap into conduits
that feed springs or sinkholes (Veni 2013, p. 47). Precipitation cycles
and agricultural activity appear to be the two main factors causing
variation in the aquifer levels (Land and Newton 2008, p. 189).
However, the Roswell Artesian Basin provides an example of a
rechargeable artesian aquifer, where water reduction measures and high
levels of rainfall in the 1970's led to a reversal in long-term
hydraulic head declines and allowed this aquifer to recharge (Land and
Newton 2008, p. 190).
Suitable Water Quality
Members of the Cyprinodon genus are known for their wide
physiological tolerance relative to many other freshwater fishes. Pecos
pupfish are able to tolerate a wide range of water quality conditions
(Hoagstrom and Brooks 1999 entire). In areas where the salinity
gradient changes, Pecos pupfish dominate the areas with the highest
salinities (Hoagstrom and Brooks 1999 p. 12). However, at salinities
greater than 35,000 mg/L, larval and egg development are suppressed or
halted (Hoagstrom and Brooks 1999, p. 21; Propst 1999, p. 67). Pecos
pupfish can also tolerate low dissolved oxygen for at least short
periods, with measurements of dissolved oxygen levels as low as 2.5 mg/
L during Pecos pupfish sampling (Hoagstrom and Brooks, 1999, p. 31;
Propst 1999, pp. 67-68). These tolerance limits are further supported
by extremes of temperature, dissolved oxygen, and salinity, often
resulting in pupfish mortality (Hoagstrom and Brooks 1999, p. 21;
Propst 1999, p. 67). In addition to natural impacts to water quality,
industrial and agricultural pollutants have been shown to negatively
impact Pecos pupfish (Houston et al. 2019, p. 33).
Habitat Diversity
The Pecos pupfish occurs in a variety of aquatic environments with
a variety of underwater features that provide topographic diversity,
such as crevices, boulders, large rocks, scattered pebbles, and aquatic
plants provide topographic diversity throughout the range (Kodric-Brown
1975, p. 35; 1977, pp. 750-751, 753-756, and 761-762).Pecos pupfish
typically occupy pools and shallow runs and riffles (Hoagstrom and
Brooks 1999, pp. 36, 45). For reproduction, Pecos pupfish require
shallow water less than 2 m (6.56 ft) deep and in areas with
topographic diversity (Kodric-Brown 1977, pp. 750-751). Rocky
embankments appear to be the most desirable breeding substrate, as the
most aggressive and largest males occupy these areas at Mirror Lake,
Bottomless Lakes State Park, Chaves County, NM (Kodric-Brown 1975, pp.
34-35). The percentage of males holding territory can vary year to year
and is influenced by the amount of breeding and foraging habitat
available (dependent on water levels), and that density of territorial
males was highest in dense patches of aquatic vegetation, and lowest in
flat silty areas with isolated rocks (Kodric-Brown 1975, pp. 20, 34-
35). During the colder months when water temperatures drop below 10
[deg]C (50 [deg]F), Pecos pupfish become inactive and can be found in
deeper water with dense vegetation and flocculent material (such as
fine detritus or non-living organic matter) present in the substrate
(Kodric-Brown 1977, p. 752; Hoagstrom et al. 2015, p. 17).
For the Pecos pupfish to be resilient, each population needs to be
able to withstand stochastic events or disturbances that can
drastically alter local ecosystems. Populations of Pecos pupfish need
to have enough individuals (abundance) and occupy multiple types of
habitats with sufficient water quantity and quality, (habitat
diversity), such as sinkholes, streams, and wetlands to withstand
stochastic events. Additionally, populations need to exist in locations
where environmental conditions provide suitable habitat and water
quality such that adequate numbers of individuals can be supported.
Without all these factors, a population has an increased likelihood for
localized extirpation.
For a species to persist over time, it must exhibit attributes
across its range that relate to either representation or redundancy.
Representation describes the ability of a species to adapt to changing
environmental conditions over time and is characterized by the breadth
of genetic and environmental diversity within and among populations
(Shaffer and Stein 2000, p. 308). For the Pecos pupfish to exhibit
adequate representation, resilient populations should occur within the
Pecos River Basin to which it is native. The breadth of morphological,
genetic, and behavioral variation should be preserved to maintain the
evolutionary variation of the species.
Redundancy describes the ability of a species to withstand
catastrophic events (Tear et al. 2005, p. 841; Redford et al. 2011, p.
42). Adequate redundancy minimizes the effect of localized extirpation
on the range-wide persistence of a species (Shaffer and Stein 2000, p.
308). Redundancy for the Pecos pupfish is characterized by having
multiple, resilient, and representative populations across the range of
the species. Also important for measuring redundancy is the
connectivity among discrete populations that allows for immigration and
emigration between populations and increases the likelihood of
recolonization should a population become extirpated. In the case of
the Pecos pupfish, however, increasing connectivity among populations
can present a hybridization risk.
[[Page 92750]]
Threats
Following are summary evaluations of four threats analyzed in the
SSA report for the Pecos pupfish: introgression of the sheepshead
minnow (Factor E), the loss and decline of surface and ground water,
degradation of water quality, and habitat loss and fragmentation
(Factor A), which are exacerbated by the effects of climate change
(Factor A). We also evaluate existing regulatory mechanisms (Factor D)
and ongoing conservation measures.
In the SSA report, we also considered two additional threats:
golden algal blooms (Factor A) and competition for food resources
(Factor C). We concluded that, as indicated by the best available
scientific and commercial information, these threats are currently
having little to no impact on Pecos pupfish populations and thus the
overall effect of these threats now and into the future is expected to
be minimal. Therefore, we will not present summary analyses of those
threats in this document, but we considered them in the current and
future condition assessments in the SSA report. For full descriptions
of all threats and how they impact the species, please see the SSA
report (Service 2024, pp. 43-44).
Sheepshead Minnow Introgression
The sheepshead minnow is a threat to the Pecos pupfish through
hybridization and competition for resources (Echelle et al. 2003b,
entire; Echelle and Connor 1989, pp. 725-726). Pecos pupfish and
sheepshead minnow lack isolating mechanisms and readily interbreed, and
within as few as 5 to 7 years hybridization leads to the complete loss
of genetically pure (non-introgressed) Pecos pupfish in the area of
introgression (Cokendolpher 1980, entire; Echelle and Connor 1989, pp.
725-726; Echelle et al. 2003b, entire; Kodric-Brown and Rosenfield
2004, entire). Once a population is no longer genetically pure, it no
longer exists. In addition, research suggests that the hybrid fish grow
faster and are larger than pure Pecos pupfish, and thus outcompete
genetically pure Pecos pupfish for resources (Rosenfield et al. 2004,
p. 1595). Pecos pupfish hybridization with the sheepshead minnow is one
of the greatest threats to this species and is cited as the cause of
extirpation from historical sites (Echelle and Connor 1989, pp. 725-
726; Echelle et al. 2003b, entire; Pecos Pupfish Conservation Team
(Conservation Team) 2022, p. 5).
The New Mexico State Game Commission and Texas Parks and Wildlife
Department (TPWD) implemented State fishing regulations that prohibit
use of sheepshead minnow in the bait harvest and use program since
1999. However, this nonnative invasive species occurs within the lower
Pecos River, below the Red Bluff Reservoir, and may be unintentionally
captured, transferred, and released into Pecos pupfish habitat, and
thus remains an ongoing threat (Conservation Team 2022, pp. 3, 5).
While the Red Bluff Reservoir provides a physical barrier that prevents
sheepshead minnow from naturally moving into the middle Pecos River,
and the Brantley Dam and Reservoir provide a barrier that prevents the
sheepshead minnow from naturally moving into the upper Pecos River,
recreational fishing occurs throughout the river, so it is highly
likely that a bait-bucket transfer would lead to an introduction of
sheepshead minnow and result in the introgression of the population of
Pecos pupfish within the upper Pecos River. Fish barriers have been
installed at Bitter Lake NWR and at the BLM Overflow Wetlands to
prevent entrance of sheepshead minnow from the mainstem Pecos River.
Loss and Decline of Surface and Groundwater
Adverse impacts to both water quantity and, to a lesser extent,
water quality, are threats to Pecos pupfish viability. As anthropogenic
uses of water increase from urban, agricultural, and industrial
development, water management will become more important to maintain
adequate water for the Pecos pupfish. While the demand on water in the
Pecos River Basin is expected to increase based on climate change
projections (Sites Southwest 2008, pp. 6-3, 6-6), we have reasonable
certainty that there will be adequate aquifer levels until 2100
(Llewellyn et al. 2021, pp. 99-100). Although diversions from the Pecos
River are capped by existing water rights, agreements, and regulations,
decreasing surface water availability can increase the demand for
pumped ground water (Dunbar et al. 2022, p. 87).
In New Mexico, population growth in Chaves County, which contains
the majority of current occupied Pecos pupfish sites, averaged a 1.3
percent annual growth rate between 1960 and 2010 (Consensus Planning,
Inc. 2016, p. 10) but a 1.9 percent annual decline between 2010 and
2020. The Pecos Valley Artesian Conservancy District (PVACD) regulates
ground water use within the aquifer and supplies water to about 110,000
acres of crops/year (Llewellyn et al. 2021, p. 47). The amount of water
withdrawn causes seasonal variability in aquifer levels, but yearly
fluctuations in ground water levels typically remain similar (PVACD
2023, entire). The long-term average water level has remained constant.
Water availability in the Pecos River is influenced by a variety of
factors including human development, primarily agriculture. However,
this river is currently managed for multiple uses, including endangered
species conservation, and future human water use from the river is not
expected to substantially increase in the future.
In Texas, the Delaware River, 12 mi (19.31 km) north of Salt Creek
(TX), is experiencing an increase in ground water pumping to support
hydraulic fracturing (fracking) operations, and we expect the increased
water usage to continue around Salt Creek (TX) (Scanlon et al. 2020,
pp. 3510-3513). Both a deep and shallow aquifer (Rustler and Pecos
Valley complex) may support the springs feeding Salt Creek (TX) (George
et al. 2011, pp. 4, 58, 146). However, there are no specific hydrologic
models detailing how the aquifers influence the flows in Salt Creek
(TX). Conversely, fracking is not a threat to the Pecos pupfish
populations in New Mexico as the oil formations there are structured
differently than those in Texas.
Water use may increase with a growing human population, potentially
further depleting ground-water storage and negatively influencing the
Pecos pupfish's future (Llewellyn et al. 2021, p. 84). Activities such
as surface and groundwater withdrawals, as well as impoundments, have
decreased streamflow resulting in direct habitat loss and increased
habitat fragmentation (Llewellyn et al. 2021, p. 138). Karst aquifer
systems, like that found on Bitter Lake NWR, may affect sinkhole
systems, as groundwater pumping may tap into conduits that feed springs
or sinkholes (Veni 2013, p. 47). Precipitation cycles and agricultural
activity appear to be the two main factors causing variation in the
aquifer levels (Land and Newton 2008, p. 189). We are uncertain of how
the aquifers will be affected and recover (rainfall and recharge), if
at all, and how reduced surface flows (irrigation) would be affected by
human population growth (Land and Newton 2008, p. 190).
The Pecos River provides connected wetted habitat year-round. There
are four federally owned reservoirs on the Pecos River: Santa Rosa
(U.S. Army Corps of Engineers (Corps)); Sumner (BOR); Brantley (BOR);
and Avalon (BOR), and the ground water rights are owned by the NM
Interstate Stream Commission (Service 2017, pp. 7 and 11). The State
and Federal agencies
[[Page 92751]]
work together to maintain river flows that provide water for a variety
of reasons, including environmental reasons. For the last few decades,
the only releases from Fort Sumner Reservoir to Brantley Reservoir have
been block releases that occur several times a year at intervals and
timing contrary to the historical flow regimes, leading to artificially
low flows (Hoagstrom et al. 2008, p. 6). These block releases manage
for the threatened Pecos bluntnose shiner (Notropis simus pecosensis)
and act as a buffer to drying events even though the water may be
repurposed from environmental use to consumptive irrigation use, and
will be beneficial to the Pecos pupfish (Hoagstrom et al. 2008, p. 6).
Degradation of Water Quality
Because Pecos pupfish are relatively tolerant of more extreme water
quality conditions (high temperatures, low dissolved oxygen, high
salinity), minor changes to water quality are generally seen as less of
a concern (Propst 1999, p. 68). However, throughout the Pecos pupfish's
range, water temperatures have the potential to exceed the fish's
thermal tolerance (Brown and Feldmeth 1971, entire). Furthermore, it is
surmised that extreme salinity caused declines in two historical Pecos
pupfish populations in two springs in Laguna Grande De la Sal, NM
(Hoagstrom and Brooks 1999, pp. 13-16).
The entirety of the Pecos pupfish range in the Pecos River has
ongoing water quality concerns and is considered impaired by the New
Mexico Environmental Department (Llewellyn et al. 2021, pp. 27-29).
Below Sumner Reservoir, the river improves for 160 km (100 mi) before
becoming impaired by nutrients from irrigation return flow, urban
runoff, and municipal wastewater treatment plant effluent to the State
line (Llewellyn et al. 2021, pp. 27-28). Another stressor is
contamination of water by oil and gas development (Bonetti et al. 2021,
entire). Pipelines present another potential route of contamination, as
leaks or ruptures may allow oil, gas, or brines to enter underground
aquifers that contribute to spring flow or by point sources from spills
and leaks on the surface (Ashworth 1990, p. 31). Oil and brine
contamination may impair water quality to the extent that Pecos pupfish
will be unable to carry out metabolic functions (e.g., breathing)
(Bonetti et al. 2021, p. 4). However, the pipelines in the vicinity of
Bitter Lake NWR, BLM Area of Critical Environmental Concern (ACEC), and
Bottomless Lakes State Park are protected and managed to keep these
systems conserved and free from contamination.
Global Climate Change and Drought
The Southwest United States is thought to be extremely sensitive to
increased drought and higher average temperatures caused by climate
change (Sheffield and Wood 2008, p. 101). In particular, temperatures
across New Mexico, including in the Pecos River Basin, have risen
approximately 1.1 [deg]C) (2 ([deg]F) between 1970 and 2020 (Dunbar et
al. 2022, pp. 4-5). While Pecos pupfish have persisted through
historical drought conditions, observations from Bitter Lake NWR
suggest that prolonged drought or higher temperatures have likely led
to mortality events (Jacobsen 2023, entire). Because Pecos pupfish are
able to persist in degraded, saline water conditions, they are likely
to be somewhat resilient to adverse water flow and temperature impacts
(Propst 1999, pp. 67-68). However, Pecos pupfish are likely persisting
at or near their thermal maximum, particularly during the hottest parts
of the year (Matthews and Zimmerman 1990, p. 27). The increasing
temperatures predicted by climate modeling suggest that water
temperatures have the potential to exceed the thermal maximum for Pecos
pupfish (Llewellyn et al. 2021, p. 88). This is particularly crucial
for sites that are shallower, have limited freshwater input, or are
isolated from any potential thermal refugia. Observations of the
Conchos pupfish (C. eximius), a close relative of the pupfish, suggest
that drought may have caused declines in fish numbers (Davis 1980, p.
83).
Climate change manifests in a variety of ways. An average increase
in temperature manifests itself locally as higher daytime temperatures
and higher overnight low temperatures (Hayhoe et al. 2018, p. 88). In
terms of precipitation, broadly speaking, wet areas are expected to get
wetter and experience more intense precipitation events, while dry
areas are expected to get drier and experience more intense drought
events (Shafer et al. 2014, pp. 443-445; Kloesel et al. 2018, pp. 995-
996, 1004). Another effect of climate change is exacerbated drought due
to feedback loops between high air temperatures, low humidities, and
low soil moisture (Cheng et al. 2019, pp. 4437-4440). Potential effects
of climate change that are likely to affect water quality and quantity
include increased temperatures, evaporation, evapotranspiration,
drought, earlier runoff, and reduced or increased precipitation
(Llewellyn et al. 2021, p. 98). The main uncertainty of a changing
climate is the resulting demands on surface and ground water aquifers
that support habitat for the Pecos pupfish, thereby reducing water
quantity and leading to impaired water quality.
Habitat Loss and Fragmentation
Groundwater depletion has dried up several marshes, playas, and
spring ponds formerly occupied by Pecos pupfish adjacent to the Pecos
River in New Mexico and Texas (Hoagstrom and Brooks 1999, p. 11).
Direct habitat loss was also believed to have caused the extirpation of
Comanche Springs pupfish (C. elegans) in Texas near Fort Stockton
(Echelle et al. 2003a, p. 114). Habitat loss occurs when streams are
dewatered, and surface flow is eliminated. To date, we are unaware of
habitat loss within the range of the species at a scale that has caused
the extirpation of Pecos pupfish in an entire population. However,
significant habitat impairment has occurred throughout the range of the
Pecos pupfish. For example, the Pecos River has been significantly
altered through dam construction, channelization, and water diversions
resulting in the loss of off-channel marshes, oxbows, and changes to
mainstem flows (Hoagstrom and Brooks 1999, pp. 10-12).
While we have no data regarding to what extent the Pecos pupfish
use off-channel marshes and oxbows, based on habitat descriptions of
the current known occupied locations we presume that at least a portion
of the available off-channel habitat may have been used by Pecos
pupfish for connectivity (Hoagstrom and Brooks 1999, p. 22).
Furthermore, research suggests that habitat fragmentation and
alteration may have rendered Pecos pupfish populations in the lower
Pecos River more vulnerable to hybridization with the sheepshead
minnow, and identified morphological differences between populations
that are linked to aquatic habitat type and diversity (Collyer et al.
2015, p. 191). Similarly, pupfish need large and connected populations
to have a chance to potentially withstand introgression (Collyer et al.
2015, p. 191). More recently, in 2020, 2022, and 2023, drought events
led to the loss of portions of Bitter Creek on Bitter Lake NWR, with
Pecos pupfish mortality observed in 2020 and 2022. Data collected
during winter surveys suggest that the Pecos pupfish is able to return
to sections of the creek once sufficient water quantities are present.
Although data are lacking from the Pecos River mainstem, this scenario
likely occurs there as well.
[[Page 92752]]
Habitat fragmentation is the disruption of continuous habitat
resulting in smaller disconnected areas and can be either temporary or
permanent (Wiegand et al. 2005, p. 109). The natural landscape for the
Pecos pupfish comprises isolated sinkholes with unknown subsurface
connectivity, disjunct wetlands and ephemeral streams, and a
historically well-connected river system. Much of the direct habitat
loss and fragmentation within the range of the Pecos pupfish is the
result of dewatering of habitat as a result of anthropogenic
development, and water management and use, such as demand for water for
agriculture and oil and gas development (Hoagstrom et al. 2008, p. 6).
Climate change impacts in the Pecos River Basin will likely result in
higher overall surface temperatures. In general, warming surface
temperatures directly impact evapotranspiration rates and can lead to
lowered surface water (Llewellyn et al. 2021, p. 21). However,
throughout the range of the Pecos pupfish the hydrology impacting their
habitat is a complicated mix of evaporation, spring flow, and
groundwater recharge.
The loss of habitat connectivity and the resulting fragmentation
can lead to isolation among populations, which may have caused a
genetic bottleneck in some Pecos pupfish populations (Collyer et al.
2015, p. 191; Whiteley 2023, pp. 6-7). Isolated and small populations
are also more susceptible to stochastic events and amplify the effects
of inbreeding depression and genetic drift (Rieman and Allendorf 2001,
p. 762). Fragmentation and isolation of habitats can increase the risk
of local extirpation as recolonization from adjacent populations is
less likely (Hoagstrom et al. 2008, p. 13). As habitat loss and
fragmentation increases, habitat diversity decreases.
Summary of Threats
The greatest threats to the Pecos pupfish are introgression with
sheepshead minnow, loss and decline of surface and ground water,
degradation of water quality, habitat loss and fragmentation, and the
effects of climate change. Introduction of sheepshead minnow into new
locations occupied by Pecos pupfish could lead to rapid introgression,
replacing the genetically pure population with Pecos pupfish hybrids.
Research has found Pecos pupfish populations that are already
negatively impacted by habitat alteration are likely more at risk of
introgression because the reduction in habitat increases competition
for breeding substrate (Kodric-Brown and Rosenfield 2004, pp. 121-122;
Collyer et al. 2015, p. 191). Anthropogenic water use and management
has impacts on most of the surface water and groundwater within the
range of the Pecos pupfish, and continued development and climate-
driven changes to water availability will continue to impact the
species in the future. Climate change impacts including higher average
annual temperatures, more variable or lower average annual
precipitation, and increased drought frequency, are currently impacting
the Pecos pupfish and will likely continue to do so. Increasing
temperatures increase the risk that shallow habitat could exceed the
thermal tolerance of Pecos pupfish, and the resulting increased
evapotranspiration leads to lowering of water levels with the potential
for corresponding increases in salinity and water temperatures and
lowered dissolved oxygen.
Conservation Efforts and Regulatory Mechanisms
In 1999, a conservation agreement was developed to address the
threats to Pecos pupfish (Conservation Team 1999; entire). Since
implementation of the conservation agreement, conservation efforts have
included sheepshead minnow eradication, installation of fish barriers,
and enforcement of State fishing rules in an effort to protect the
Pecos pupfish from further introgression of sheepshead minnows or
hybrids and alleviate other threats affecting the Pecos pupfish
(Conservation Team 2022, p. 3). The conservation agreement was amended
in 2013 and in 2022 (Conservation Team 2022, pp. 1, 4).
These above-mentioned stressors--introgression, water quantity, and
habitat degradation and loss--have been considered and some have been
reduced through the implementation of the conservation agreement
(Conservation Team 2022, entire). The agreement has eight signatory
agencies: TPWD; New Mexico Department of Game and Fish (NMDGF); New
Mexico Energy, Minerals, and Natural Resources Department; New Mexico
Department of Agriculture; New Mexico Interstate Stream Commission;
Commissioner of Public Lands; New Mexico State Land Office; BLM; and
the Service (Conservation Team 2022, pp. 8-23). The duration of the
conservation agreement is indefinite with formal review every 10 years
(Conservation Team 2022, p. 12).
Since 1999, one fish barrier has been installed at Bitter Lake NWR,
near the confluence with the Pecos River. In 2019, two fish barriers
were replaced at the BLM Overflow Wetlands, where north and south
concrete barriers were installed to prevent the entrance of fish from
the mainstem Pecos River into the complex. The barrier on the BLM
Overflow Wetlands not only protects the wetlands, but also protects the
Bottomless Lakes complex from the threat of hybridization.
Moving forward, the conservation agreement will continue to provide
guidance for agencies and partners working towards Pecos pupfish
conservation, help provide for ongoing maintenance of fish barriers,
installation of additional fish barriers, and enforcing existing State
and Federal baitfish regulations.
The Fort Worth Zoo and other collaborating zoos have successfully
bred Pecos pupfish in captivity since 2000. Captive conservation
efforts have focused on propagation techniques, animal husbandry
research, and propagation for stocking. Beginning in 2012, the State of
Texas began working with private landowners within the Pecos River
watershed to identify opportunities for the development of Pecos
pupfish production ponds. Two ponds were established in 2024;
recruitment of additional landowners and establishment of additional
ponds is ongoing. The goal of the ponds is to sustain the genetic
lineage from the Salt Creek, TX, population, create stable habitats
isolated from potential sheepshead minnow incursion with secure water
sources, and provide a stock of fish that can be used to establish
other locations.
Current Condition
A thorough review of the Pecos pupfish's current condition is
presented in chapter 4 of the SSA report (version 1.2, Service 2024,
pp. 46-74).
We divided the Pecos pupfish's range into nine analysis units (AU)
(Figure 1). Currently, the Pecos pupfish is distributed across seven of
nine AUs covering the historical range; two of the AUs are considered
extirpated (figure 1; table 3; Service 2024, figure 20, p. 52). We
defined Pecos pupfish AUs based on documented occurrences, U.S.
Geological Survey hydrological unit code (HUC)-12 sub-watershed
boundaries, stream and river features, and barriers (such as Brantley
Reservoir and Red Bluff Reservoir) (Service 2024, p, 51). This approach
is based on the assumption that the closer occurrences are (such as
within the same AU), the more likely similar environmental processes
are influencing the sites where the fish occurs. We evaluated the
current viability of Pecos pupfish using
[[Page 92753]]
population resiliency and species' redundancy and representation.
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[[Page 92754]]
The species is known from nine analysis units.
Table 2--Analysis Units for the Pecos Pupfish
------------------------------------------------------------------------
Analysis unit Land ownership
------------------------------------------------------------------------
1: Upper Pecos River......................... BLM, State, private.
2: Salt Creek Wilderness..................... FWS.
3: Bitter Creek Drainage..................... FWS.
4: Bitter Lake NWR Middle Tract Wetlands..... FWS.
5: Bottomless Lakes State Park............... State.
6: BLM Overflow Wetlands and Lea Lake........ BLM, State.
7: Middle Pecos River........................ BLM, State, private.
8: Salt Creek (TX)........................... Private.
9: Lower Pecos River......................... BLM, State, private.
------------------------------------------------------------------------
To assess resiliency, we developed a qualitative model that
incorporates one demographic metric (occurrence) and three habitat
metrics (water quantity, water quality, and habitat diversity), and
genetic security into the overall status for each unit (table 3). We
selected habitat diversity as a metric as habitats with multiple
aquatic environments may better allow the fish to withstand changing or
adverse conditions.
To assess redundancy of the Pecos pupfish, we examined (1) how many
extant sites exist within each AU, (2) how connected these sites are
within the unit, and (3) how connected each unit is to nearby units.
Importantly though, the diversity of the habitat, and not the number of
sites Pecos pupfish have been detected, reflects the extent of the
occupied Pecos pupfish habitat within the unit. For example, Bitter
Creek (on Bitter Lake NWR) is approximately 1,546 m (5,072 ft) of
variably wetted stream and is counted as a single site. Similarly, the
BLM Overflow Wetlands cover over 1,000 acres (405 ha) and is also
counted as a single site. However, we assume that with the exception of
the sites delineated on the upper Pecos River, which is a riverine
environment, each site is representative of a discrete aquatic
environment.
To assess representation, we used aquatic environment (riverine,
shallow stream, sinkholes, and wetlands) as a surrogate for genetic
data. Genetic studies of Pecos pupfish have revealed important genetic
relationships across the range of the species. The population of Pecos
pupfish in the upper reaches of Salt Creek (TX) shows a specific allele
that is unique to this location (Echelle et al. 2003b, p. 6). Recent
work in the northern portion of their range has found that Pecos
pupfish populations in the Bottomless Lakes State Park and BLM Overflow
Wetland (AUs 5 and 6, respectively), are highly genetically
differentiated from each other and from other populations (Whiteley
2023, pp. 7-9, 18). Additionally, individuals sampled from Bottomless
Lakes State Park showed high inbreeding coefficient, (Whiteley 2023, p.
26). Analysis showed distinct clustering of Pecos pupfish at two sites
at Bottomless Lakes State Park (Mirror Lake and Lazy Lagoon) and all of
the sampled sites at Bitter Lake NWR (Whiteley 2023, p. 18). On Bitter
Lake NWR, two distinct clusters were observed that may indicate gene
flow (Whiteley 2023, p. 19). The sampled sites in the Middle Tract
Wetlands clustered with each other and Bitter Creek, while the four
sample sinkholes all clustered with each other (Whiteley 2023, p. 8).
While that data analyzed by Whitely (2023, entire) did not attempt to
infer a relationship between environmental factors, a result that might
reflect either developmental plasticity or local genetic adaptation,
research does suggest that Pecos pupfish morphology differs depending
on the aquatic environments (i.e., habitat diversity) (Echelle and
Echelle 2007, p. 7; Collyer et al. 2015, p. 187-189; Xu 2017, pp. 22,
26-27; Whiteley 2023, entire).
Table 3--Condition Criteria Resiliency Analysis Metrics as Applied to Each Analysis Unit
--------------------------------------------------------------------------------------------------------------------------------------------------------
Condition Genetic security Occurrence Water quantity Water quality Habitat diversity
--------------------------------------------------------------------------------------------------------------------------------------------------------
High condition (high resiliency).. No evidence of Extant or presumed Stable and sufficient No severe impairments Unit has a diverse
introgression with extant observed at, water availability to water quality habitat assemblage
sheepshead minnow. or in the vicinity throughout the unit. documented and no within the unit
of, each of these Low flow or drying recorded (streams/river,
sites at least once events documented, contamination events. wetlands, and
within the last 5 but no long-term sinkholes).
years. drying events
recorded.
Moderate condition (moderate Introgression possible Two or fewer of the Occasional low flows Occasional water Fish restricted to
resiliency). in the unit, but no known occupied sites or drying events quality impairments just a single
confirmation. confirmed or presumed across <50% of the documented, likely habitat type within
extirpated. unit with rare long- linked to low flows. the unit.
term drying events No documented
documented. exposure to surface
contaminants.
Low condition (low resiliency).... Introgression only in Pupfish extant at 50% Routine low flows and Documented exposure to N/A.
a portion of the or fewer of sites drying events across surface contaminants
unit. identified. the majority of the within much of the
Populations low unit and regular long- unit.
enough that fish are term drying events.
not detected on 50%
or more visits to
occupied locations.
Likely extirpated................. Confirmed N/A N/A N/A N/A.
introgression
throughout the unit.
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 92755]]
Fundamental to our analysis of the Pecos pupfish was the
determination of scientifically sound analytical units at a scale
useful for assessing the species. As there is little information
available regarding the demographic or genetic processes that define
the spatial structure of Pecos pupfish populations, we relied on
spatial occurrence data to define a suitable extent for our AUs. Within
each AU, we identified discrete sites where Pecos pupfish have been
documented to occur during past sampling and inventory efforts (Brooks
1992, entire; Hoagstrom and Brooks 1999, entire; National Heritage New
Mexico (NHNM) 2021, entire; GBIF 2022, entire). These sites represent
the documentation of at least one Pecos pupfish at a specific location
at a point in time. Many of these sites have not been routinely visited
or have been visited only once. Eleven sampling locations representing
nine sites have been annually sampled (Hatt 2022, p. 5). In some cases,
such as sinkholes, these sites are analogous to subpopulations. In
others, such as the Pecos River or BLM Overflow Wetlands, the
documented sites represent only the accessible portion of the habitat
and likely do not represent the entire population in the area.
Based on the available data and our understanding of Pecos pupfish
ecology, we developed a basis for assigning a risk category for each
metric at the population AU level (table 4). The risk category reflects
a qualitative determination of the likelihood that the species'
response to the conditions described in each individual metric, over
the 20-year period following the year 2023, would be extirpated from a
given population AU. This 20-year timeframe correlates with
approximately 20 1-year generations, which is near the maximum of the
presumed Pecos pupfish lifespan in the wild.
Table 4--Qualitative and Quantitative Descriptions of the Three Risk Categories Used in the Resiliency Analysis
----------------------------------------------------------------------------------------------------------------
Estimated chance Numerical
Risk category Analysis unit of extirpation for extirpation risk Threats
condition 20 years estimate characterization
----------------------------------------------------------------------------------------------------------------
Low risk........................ High condition..... Extirpation is <10% Threats to pupfish
very unlikely. needs are
minimized or
limited in spatial
extent within the
unit.
Moderate risk................... Moderate condition. Extirpation is 10-40% Threats to pupfish
unlikely. needs are
widespread
throughout the
unit but limited
in duration or
severity.
High risk....................... Low condition...... Extirpation risk >40% Threats to pupfish
ranges from being are severe and
about as likely pervasive
as not to being throughout the
very likely. unit.
----------------------------------------------------------------------------------------------------------------
We ranked and scored the individual metrics as one (low), two
(moderate) or three (high), based on criteria described in table 3,
then combined them to produce a categorical condition score for each
AU. We then averaged that score across all four categories to develop
an overall unit score. For the overall unit score, an average of
greater than 2.6 was considered high condition, 1.6 to 2.5 was
considered moderate condition, and 1.5 or less was considered low
condition. To aid in the comparison of AUs (with each other and under
various future scenarios (see the Future Condition section, below)) and
assess the species' viability, we categorized the final condition
scores as ``high'' (population generally secure), ``moderate''
(population marginally secure), or ``low'' (population generally
insecure). We based these categories primarily on our understanding of
Pecos pupfish habitat needs, known stressors, and the principles of
conservation biology. We acknowledge that there is uncertainty
associated with this model and some of the supporting data; however,
the methodology is appropriate for assessing the status of the Pecos
pupfish across its range given the best available information.
Resiliency
Unit 1: Upper Pecos River: Pecos pupfish remain extant in the upper
Pecos River. Based on their preference for slower, warmer, and more
saline conditions, and observations from surveys conducted in support
of other routine fish monitoring, Pecos pupfish are limited to specific
areas within the upper Pecos River channel and these areas likely shift
both spatially and temporally. This situation is reflected in data that
show varying numbers of Pecos pupfish in year-to-year sampling and seem
to indicate that, during periods of drying, Pecos pupfish are often
more represented in samples (Davenport 2023b, entire). Although it is
unclear if any particular site in the upper Pecos River has been lost,
the highly variable nature of this river section and shifting
populations likely means that sampling at the same site will not always
detect the Pecos pupfish.
The upper Pecos River is subject to regular severe low flows and
intermittent drying (Follansbee et al. 1915, p. 452; Hatch et al. 1985,
p. 561; Hoagstrom et al. 2008, p. 6). Because this situation threatens
the persistence of the federally threatened Pecos bluntnose shiner,
conservation measures are in place by the BOR through a biological
opinion (under section 7 of the Act) to minimize intermittent drying.
These measures buffer the threat of river drying for Pecos bluntnose
shiner and, by extension, Pecos pupfish. The entire Pecos pupfish range
in the Pecos River has ongoing water quality concerns and is considered
impaired due to nutrient loading, discharges from municipal wastewater
treatment plant discharges, and livestock grazing (Llewellyn et al.
2021, pp. 28-29). The current condition evaluation for the upper Pecos
River population determined that occurrence, water quality, and habitat
diversity are in moderate condition, and water quality is in low
condition. Thus, the Upper Pecos River population is determined to be
in overall moderate current condition and has moderate resiliency.
Unit 2: Salt Creek Wilderness: No routine Pecos pupfish monitoring
occurs within the Salt Creek Wilderness AU. Pecos pupfish remain extant
in Salt Creek (NM) and likely at three sinkholes in the unit (Inkpot,
Little Inkpot, and New Sinkhole). A visit to Salt Creek (NM) in
February 2023 confirmed presence of the pupfish but also documented a
mortality event of several thousand mostly juvenile pupfish from an
undetermined cause (Jacobsen 2023,
[[Page 92756]]
entire). Although Pecos pupfish remain extant at several locations in
the unit, the habitat available within the unit is small, so this
stream unit may be subject to mortality events. Pecos pupfish are
presumed to have been extirpated from Pren's Hole, though the cause is
unknown (Hatt 2019, p. 5). Pren's Hole seemingly was colonized by a
flash flood (Hoagstrom and Brooks 1999, p. 16).
We have no recent data on water quality or quantity within this
unit from the sinkholes or Salt Creek (NM). Deeper sinkholes generally
have stable conditions, both in water quantity and quality, and thus we
assume that likely holds true for the sinkholes in this unit as pupfish
need large populations and room for expansion (Collyer et al. 2015, p.
191). Salt Creek (NM) likely experiences routine drying events
throughout the year, and concurrently with those drying events,
impairments to temperature, dissolved oxygen, and salinity.
Though the permanent water in both stream and sinkhole aquatic
environments is supported by water from the San Andres aquifer, the
depth of the sinkholes likely provides a more stable long-term
environment. Conversely, Salt Creek (NM), although more ephemeral,
allows for Pecos pupfish dispersal throughout the unit and provides a
potential connection to the Pecos River. This diversity of habitat
helps buffer the unit against both gradual environmental changes as
well as stochastic events, such as floods or golden algae, that may
impact a single aquatic environment. The current condition evaluation
for the Salt Creek Wilderness determined that habitat diversity is in
high condition, and occurrence, water quality, and water quantity are
in moderate condition. Thus, the Salt Creek Wilderness population is
determined to be in overall moderate current condition and has moderate
resiliency.
Unit 3: Bitter Creek Drainage: Routine monitoring occurs in Bitter
Creek as well as two of the sinkholes in the unit. We extrapolated both
formal and informal monitoring data to the remainder of the unit, and
based on habitat availability presumed the Pecos pupfish remains extant
at all documented occupied sites in the unit. There have been
documented fish kills on Bitter Creek, but routine monitoring indicates
that Pecos pupfish populations in the creek remain extant, though
highly variable (Hatt 2021).
Water quality is routinely sampled, and no impairments have been
detected. Much of the water in this unit is derived from underground
springs from the San Andres aquifer. This includes all of the sinkholes
as well as the springs that feed Bitter Creek such as the Dragonfly
Spring and Lost River. The closest monitoring well to this unit shows a
long-term stable water depth trend that likely corresponds to stable
spring flows in the unit (Pecos Valley Artesian Conservancy District
(PVACD) 2023, entire). The water in Bitter Creek is supplemented by
precipitation. Because evaporation exceeds precipitation across the
Pecos River Basin, during drought years, portions of Bitter Creek dry
out (Land 2003, p. 230).
Though the permanent water in both the stream and sinkhole aquatic
environments is supported by water from the San Andres aquifer, the
depth of the sinkholes likely provides a more stable long-term
environment. Bitter Creek is supported by both seasonal precipitation
as well as spring flows from Dragonfly Spring and the Lost River. This
diversity of habitat helps buffer the unit against both gradual
environmental changes as well as stochastic events, such as floods or
golden algae, that may impact a single aquatic environment. The Bitter
Creek Drainage population's current condition evaluation determined
that occurrence, water quality, and habitat diversity are in high
condition, and water quality is in moderate condition. Thus, the Bitter
Creek Drainage population is determined to be in overall high current
condition and has high resiliency.
Unit 4: Bitter Creek Middle Tract Wetlands: Pecos pupfish are
routinely monitored at three sites within the Middle Tract Wetlands AU,
however, most of the impoundments listed as occupied have not been
surveyed in decades (Hatt 2022, p. 5). Despite this lack of data, we
presume that the Pecos pupfish remains extant at all documented
occupied sites in the unit, due to both their connection to occupied
habitat and the absence of any known mortality event. While Pecos
pupfish are not always detected at the monitoring sites during
consecutive surveys, they have been shown to remain extant within those
sites (Hatt 2019, p. 5; Hatt 2022, p. 5).
This unit is composed of artificial wetlands and ditches that are
managed by Bitter Lake NWR. The ditches are spring fed and retain
permanent water. The wetland impoundments vary widely in habitat
extent, and while many are likely to retain permanent water in most
years, given the variable nature of the water in the impoundments, the
amount of habitat is presumed to vary widely in any given year, and may
be extremely limited in particularly dry years.
There are no known water quality impairments in the unit that would
impact the Pecos pupfish. When water levels are low, the shallow
impoundments and wetlands in the unit are subject to adverse water
quality such as increased temperature and salinity, and decreased
available dissolved oxygen because water becomes lentic or stagnant and
soon evaporates.
Aquatic environments in this unit area are a mix of manmade
channels, impoundments, and wetlands. While we do not have data on how
Pecos pupfish move between these environments, the diversity of
habitats likely helps buffer the Pecos pupfish from short-term
environmental changes such as drought, provides ample sheltering and
breeding habitat, and provides protection from stochastic events such
as floods or golden algae blooms. Thus, the Bitter Lake NWR Middle
Tract Wetlands population's current condition evaluation determined
that occurrence, water quantity, water quality, and habitat diversity
are in overall high current condition and the population has high
resiliency.
Unit 5: Bottomless Lakes State Park: Pecos pupfish have been
routinely monitored at three sites in this AU and are found exclusively
in sinkhole habitat. While Pecos pupfish were confirmed extirpated from
Upper Figure 8 Lake during the 2021 monitoring, they remain extant
throughout the remainder of the known occupied sites within the unit,
including the adjacent Lower Figure 8 Lake sinkhole (Hatt 2021, p. 7).
All of the Pecos pupfish sinkholes at Bottomless Lakes State Park
are fed by springs from the San Andres artesian aquifer (Land 2003, p.
229). Though some historical lowering of sinkhole levels has occurred,
the recent trend is an increase in surface water levels in the
sinkholes. Water levels in the sinkholes appear to be closely related
to the overall fluctuation in water levels in the artesian aquifer
(Land 2003, p. 231). No documented water contamination either from
surface sources or natural water quality parameters has been recorded
in the unit. Although sinkholes may exhibit more stable water quantity
and quality, a mortality event was documented in 2020 in Upper Figure 8
Lake, which illustrates the susceptibility of these habitats to
stochastic events. The Bottomless Lakes State Park population's current
condition evaluation determined that occurrence, water quantity, and
water quality are in high condition, and habitat diversity is in
moderate condition. Thus, the Bottomless Lakes State Park population is
in overall high current condition and high resiliency.
[[Page 92757]]
Unit 6: BLM Overflow Wetlands and Lea Lake: Pecos pupfish in this
unit are surveyed in limited accessible areas of the BLM Overflow
Wetlands (Hatt 2022, p. 2). Pecos pupfish are presumed extant
throughout the suitable habitat within the wetland because installed
fish barriers protect the unit from sheepshead minnow introgression
(Hoagstrom et al. 2015, p. 16).
Lea Lake typically exhibits stable water quantity throughout the
year (Hoagstrom and Brooks 1999, p. 16). In addition, wetland water is
supplied by several springs throughout the complex as well as surface
flows during precipitation events. As a result of the different sources
of water, the extent of aquatic habitat varies both seasonally and
annually. However, owing to the constant source of water from Lea Lake,
as well as the springs in the complex, permanent water remains in many
locations. Additionally, there are no known water contamination issues
in this unit.
This unit contains a large wetland complex and the largest sinkhole
in Bottomless Lakes State Park. This sinkhole was not included in Unit
5 as it is not hydrologically connected to the other sinkholes in Unit
5 and is hydrologically connected to the BLM Overflow Wetlands. The
habitat diversity represented by these aquatic environments provides a
buffer from stochastic events.
The BLM Overflow Wetlands AU is the only other unit that has high
internal redundancy. Similar to the Pecos River, the BLM Overflow
Wetlands provide a large area with many microhabitats. This unit was
historically connected to the Pecos River during high flows, but fish
barriers installed to protect the unit from sheepshead minnow
introgression have limited this connection. The BLM Overflow Wetlands
and Lea Lake population's current condition evaluation determined that
occurrence, water quantity, and habitat diversity are in high
condition, and water quality is in moderate condition. Thus, the BLM
Overflow Wetlands and Lea Lake population is in overall high current
condition and has high resilience.
Unit 7: Middle Pecos River: It is likely that Pecos pupfish are
extirpated from the Pecos River between Brantley Dam and Red Bluff
Reservoir. Sheepshead minnow are regularly caught between Brantley Dam
and Red Bluff Reservoir, which indicates that they are present
throughout this segment of the Pecos River system (Davenport 2023a,
entire). Additionally, the middle Pecos River has regular issues with
severe low flows and intermittency, water quality impairments, and
stochastic events (Zymonas and Propst 2007, p. 45). The middle Pecos
River population's current condition evaluation determined that water
quantity and habitat diversity are in moderate condition, and water
quality is in low condition. Due to the presence of sheepshead minnow,
the middle Pecos River population is considered extirpated.
Unit 8: Salt Creek (TX): Pecos pupfish in Salt Creek (TX) are
currently present in only a single reach of the stream. While the fish
at this location are not routinely monitored, a visit to this unit in
2023 confirmed that fish are present (Montagne 2023, p. 2). Pecos
pupfish from the lower reach of Salt Creek (TX), near the confluence
with the Pecos River, were confirmed introgressed with sheepshead
minnow from the Pecos River. An unidentified physical barrier in the
lower reaches of Salt Creek (TX) appears to have limited the spread of
sheepshead minnow and introgressed pupfish into the upper reaches that
comprise this AU (Echelle et al. 2003b, pp. 4-6). The Salt Creek (TX)
population's current condition evaluation determined that occurrence,
water quantity, and habitat diversity are in moderate condition, and
water quality is in low condition. Thus, the Salt Creek (TX) population
is in overall moderate current condition and has moderate resilience.
Unit 9: Lower Pecos River: Pecos pupfish have been extirpated from
the lower Pecos River due to introgression with the sheepshead minnow.
The flow of the lower Pecos River north of Independence Creek is
subject to frequent and ongoing intermittency issues, regularly
experiencing no flow events, especially during the irrigation season
and during periods of drought. South of Independence Creek the
character of the river changes to one with steeper bank and canyon and
permanent water flow. The water in this unit has very high salinity and
increasing ongoing impacts from contaminants (Hoagstrom 2009, pp. 35-
36). Hazardous material spills or leaks associated with oil and gas
production are an ongoing problem in this unit and may be increasing in
both number and frequency (Scanlon et al. 2020, p. 3511). The lower
Pecos River population's current condition evaluation determined that
water quantity and habitat diversity are in moderate condition, and
water quality is in low condition. Due to the presence of sheepshead
minnow, the lower Pecos River population is considered extirpated.
Redundancy
Redundancy describes the ability of a species to withstand
catastrophic events by maintaining multiple, resilient populations
distributed (and connected, as appropriate) within the species' varied
habitats and across the species' range. We assessed Pecos pupfish
redundancy at two scales, within the individual AUs and across the
range of the species. Within the analysis unit we looked at connection
both internal to the unit and across adjacent units to characterize the
overall redundancy of a unit. The overall redundancy of the unit could
not be higher than the lowest internal or external redundancy score.
Important to the discussion of redundancy in Pecos pupfish populations
is the consideration of sheepshead minnow introgression. While
connectivity enhances redundancy within and among AUs, this same
connectivity increases the threat of sheepshead minnow introgression. A
well-connected Pecos pupfish population is one that allows for
dispersal and recolonization but is also one that is at increased risk
of introgression. Redundancy throughout the species' range, coupled
with healthy populations, may help lower the risk of introgression. A
healthy, robust Pecos pupfish population may be more resistant to
introgression and, thus, less likely to contribute to spread of hybrid
fish (Kodric-Brown and Rosenfield 2004, p. 122).
The Upper Pecos AU (Unit 1) is well connected throughout its length
and the pattern of flow within the river likely creates a variety of
microhabitat sites that are suitable for the Pecos pupfish. The Upper
Pecos is moderately connected to adjacent off-channel units, though
only at times of high flow.
The Salt Creek Wilderness unit (Unit 2) is one of two units that
are currently connected to the Pecos River during periods of high flow.
In the Salt Creek Wilderness unit, the connection to the unit is
limited to Salt Creek (NM) proper where the Pecos pupfish may be found
in only one permanent pool in Salt Creek (NM). Within this unit, Pecos
pupfish are distributed among several sinkholes and in Salt Creek (NM);
there is no known, above-ground connection between these areas.
Bitter Creek Drainage unit (Unit 3) does not have any known
connection to adjacent AUs. Internally, many of the occupied sites
within the Bitter Creek Drainage are isolated sinkholes. There is
connection along Bitter Creek and to the springs that feed the creek;
however, there is no known connection between the creek and adjacent
sinkholes. It is
[[Page 92758]]
also surmised that there may be some underground connection between the
springs in the Dragonfly Spring sinkhole area (Land and Huff 2009, p.
20). It is currently unknown how extensive this connection is (if at
all) or if a Pecos pupfish would be able to move between sinkholes
underground.
The Middle Tract unit (Unit 4) is connected to the Upper Pecos at
the southern end of the unit during periods of high flow. While pupfish
are likely widely distributed within the Middle Tract unit, connection
among the different occupied sites is managed through a series of
diversions and manmade impoundments. Water flow through the unit is
generally north to south, and when the gates between the impoundments
are open, flow is likely too great to allow Pecos pupfish to move up
the current.
The Bottomless Lakes State Park unit (Unit 5) does not have any
known connection to adjacent AUs and is fully isolated from all other
AUs.
The BLM Overflow Wetlands unit (Unit 6) is the only other unit that
has high internal redundancy. Similar to the Pecos River, the Overflow
Wetlands provide a large area with many microhabitats. This unit was
historically connected to the Pecos River during high flows, but fish
barriers installed to protect the unit from sheepshead minnow
introgression have limited this connection.
Salt Creek (TX) unit (Unit 8) is directly connected to the lower
Pecos River. There is a presumed natural barrier within Salt Creek (TX)
upstream from the confluence that moderates this connectivity. The
barrier has allowed non-introgressed Pecos pupfish to remain extant in
the upper reaches of Salt Creek (TX) despite the presence of an
introgressed population downstream. It is currently unknown how many
extant sites are found in the upper areas of Salt Creek (TX), but the
connection between them likely varies seasonally with the amount of
water in the creek.
We did not analyze the redundancy in the middle or lower Pecos
River units (AUs 7 and 9), as the Pecos pupfish populations there are
considered to be extirpated.
Representation
Representation describes the ability of a species to adapt to
changing environmental conditions over time and is characterized by the
breadth of genetic and environmental diversity within and among
populations. As previously discussed, Pecos pupfish are known from a
variety of different aquatic environmental settings and show specific
morphological variation related to these environmental settings.
Populations have been documented in sinkholes, streams, marshes,
managed wetlands, and rivers with varying physical characteristics
(i.e., size, gradient, elevation, temperature, etc.).
Although some limited genetic analysis has been done on the Pecos
pupfish that indicated potential geographic structure to Pecos pupfish
populations, research cautioned against a rigorous application of the
results since the divergence was minor (Echelle and Echelle 2007, p.
7). More recent research has shown differences between Pecos pupfish
populations among the samples from Bitter Lake NWR, Bottomless Lakes
State Park, and the BLM Overflow Wetlands (Whiteley 2023, entire), and
morphological divergence in Pecos pupfish populations that corresponded
to differing habitat use (Collyer et al. 2015, p. 187; Xu 2017, p. 22).
While there are no studies that directly relates morphological
differences in Pecos pupfish to genetic differentiation, the best
available information suggests that including a range of aquatic
environments (i.e., habitat diversity) represents much of the current
diversity of the Pecos pupfish species (Echelle and Echelle 2007, p. 7;
Collyer et al. 2015, p. 187; Xu 2017, p. 22; Whiteley 2023, entire).
Therefore, we are using environmental setting as a surrogate for
genetics to measure representation.
Currently, the Pecos pupfish is found within nearly all of the
historically occupied environmental settings but is considered
extirpated from the Pecos River in southern New Mexico and northwestern
Texas and is likely extirpated from several off-channel locations in
that same region. However, the upper Pecos River, the only remaining
riverine AU, has moderate resiliency, which reflects a potential
increase in the loss of representation of riverine Pecos pupfish in New
Mexico. The only remaining extant AU in Texas also has moderate
resiliency, which presents a risk to representation of Pecos pupfish in
Texas. Pecos pupfish have likely experienced some reduction in
representation as a result of the large range reduction following
extirpations from the Pecos River and off-channel locations in Texas
and southern New Mexico.
Assessment of Current Viability
The Pecos pupfish is currently distributed across seven of nine AUs
covering the historical range. Within those seven AUs, four were
assessed to be in high resiliency condition and three in moderate
condition. Across the range of the species, we identified 66 distinct
locations (sites) where Pecos pupfish have been recorded since 1992. As
of 2023, 8 (12.1 percent) of these 66 sites are confirmed or presumed
extirpated and four are in unknown status. The remaining 54 sites (81.2
percent) are extant or presumed extant. Twenty-one sites (31.8 percent)
have been confirmed as extant within the last 5 years. This does not
consider losses that may have occurred before the first comprehensive
range-wide surveys occurred in 1999 (Hoagstrom and Brooks 1999,
entire). There has been a large decline in the extent of the occupied
range because of the extirpation of Pecos pupfish from their historical
range in the Pecos River below Brantley Dam (southern New Mexico and
Texas). Pecos pupfish were historically found in riverine, stream,
wetland, and sinkhole habitats and currently continue to be recorded in
all of these habitats. Because of the reduction in the range caused by
the extirpation of Pecos pupfish from a large section of the Pecos
River, the species has experienced a reduction in both redundancy and
representation. However, we do not have the data on the historical size
of the Pecos pupfish population in the Pecos River or the genetic
relationship between this population and others to adequately assess
the relative importance of this population to the species. Regardless,
the species has four populations in high condition, three in moderate
condition, and none in low condition. These populations are well
distributed throughout the range and among habitat types.
Although there is uncertainty surrounding the demography of
differing Pecos pupfish populations and their genetic relationships,
data suggests that the Pecos pupfish still occurs in multiple
populations representing the historical range of habitat variation for
the species. Though declines in range extent and, likely, population
size have occurred, 11 years of monitoring data suggest that the Pecos
pupfish continues to have multiple, long-term persistent populations
throughout its range.
Future Condition
Using the same methods described for Current Condition, we assessed
viability of the Pecos pupfish under three future scenarios at two
timesteps, years 2050 and 2100, consistent with the best available
information (Service 2024, pp. 76-102). Each scenario focused on a
different climate projection for the Pecos River Basin, because
changing climate conditions will affect the Pecos pupfish's required
water quality and quantity parameters. We also assessed
[[Page 92759]]
the risk of sheepshead minnow introgression into other parts of the
species' range.
Although development such as urbanization, agriculture, and oil and
gas extraction may have local effects on some Pecos pupfish sites, we
do not expect substantial effects from these sources at the species or
AU level. The exception to this situation is the potential for oil and
gas development in the vicinity of Salt Creek (TX) to cause significant
variation in stream flow. Oil and gas development in this area is
expected to increase as energy demands are needed with increased human
development (Llewellyn et al. 2021, pp. 81, 163, 171). While we do not
have ongoing monitoring on Salt Creek (TX), stream gauges on the Black
River in New Mexico have shown a direct correlation between oil and gas
activities and reductions in stream flow, which provides relevant
context for how Salt Creek (TX) may be impacted.
Water availability in the Pecos River is influenced by a variety of
factors including human development, primarily agriculture (see Loss
and Decline of Surface and Groundwater above). However, this river is
currently managed for multiple uses, including endangered species
conservation, and future human water use from the river is not expected
to substantially increase in the future. Given these factors, we find
that the most important abiotic factors affecting Pecos pupfish
viability will result from potential changes in water availability
resulting from changing climatic conditions.
The most important biotic factor is the potential for hybridization
and genetic introgression by sheepshead minnow. If sheepshead minnow
gain access to the upper Pecos River, the Salt Creek Wilderness and
Middle Tract Wetlands AUs are most at risk of introgression because
they are both connected hydrologically to the Pecos River during
flooding events, thus allowing for potential movement of sheepshead
minnow into these off-channel habitats. In the case of the Salt Creek
Wilderness, only Salt Creek (NM) itself is vulnerable to sheepshead
minnow invasion, as the isolated sink holes in that AU are not likely
to be inundated during Pecos River flooding events. Because of the
managed nature of the Middle Tract Wetlands by the Bitter Lake NWR
staff and the existence of numerous water control structures that can
reduce opportunities for fish movement, the vulnerability within the
unit decreases with distance from the Pecos River. Managed water flows,
manmade barriers, and direct human intervention would likely be
employed to manage the spread of sheepshead minnow throughout the unit
if the species were to gain access to the upper Pecos River. The lower
portion of Salt Creek (TX) is already introgressed with sheepshead
minnow, although some upstream portions of the stream have maintained
non-introgressed pupfish. However, there is no clear barrier preventing
additional upstream movement, so we assume the risk of introgression
remains high there. The remaining three units adjacent to the Pecos
River (Bitter Creek Drainage, Bottomless Lakes State Park, and the
isolated sinkholes with the Salt Creek Wilderness) have either manmade
or natural barriers that would prevent or minimize the chance of the
spread of sheepshead minnow from the Pecos River into these units
resulting in low introgression risk.
The Intergovernmental Panel on Climate Change uses representative
concentration pathways (RCPs) in climate change scenarios to project
future concentrations of greenhouse gases (IPPC 2014, entire). Among
the RCPs, the higher values mean higher greenhouse gas emissions and
therefore higher global surface temperatures and more pronounced
effects of climate change.
To assess potential future conditions for the Pecos pupfish, we
utilized results from a study that developed projections of future
water management and hydrologic conditions to assess future water
availability across the Pecos River Basin in New Mexico (Llewellyn et
al. 2021, entire) and selected three scenarios to represent the
variability of potential future conditions that could impact the Pecos
pupfish and its habitat:
<bullet> Scenario 1: Hot and dry (RCP 8.5)--Steep increase in
annual average temperature coupled with steep decreases in annual
precipitation.
<bullet> Scenario 2: Hot and wet (RCP 8.5)--Steep increase in
annual average temperature coupled with an increase in annual average
precipitation.
<bullet> Scenario 3: Warm and dry (RCP 4.5)--Modest increase in
annual average temperature and modest decrease in annual average
precipitation.
For each of the scenarios we assumed that the Pecos Pupfish
Conservation Agreement will remain active, and the signatory agencies
will continue monitoring the biological condition of the species and
working to prevent spread of sheepshead minnow (Conservation Team 2022,
p. 3).
Assumptions and Limitations
As with any analysis, we made many assumptions that have
consequences for our projections and interpretation of Pecos pupfish
viability. First, we only used occurrence data starting in 1992 as the
basis for our analysis. This was the first published range-wide survey
of the Pecos pupfish and therefore provided the most comprehensive data
set on Pecos pupfish occurrence. Sites that were only recorded prior to
1992 were excluded from our analysis but were included in the overall
picture of historical distribution.
We were unable to locate information on thresholds or water body
sizes that equate to an increase in extirpation risk specifically for
Pecos pupfish. It is logical to assume populations that occupy smaller
and shallower habitats are less resilient, but there are no clear
thresholds in the literature at which the size raises extinction risk.
We also did not find any specific thresholds for water quality impacts
to Pecos pupfish populations that equate to a specific extirpation
risk. Pupfish, including the Pecos pupfish, are known for their
tolerance for water quality conditions that inhibit the fecundity and
survival of other fish. We assumed that populations experiencing long-
term high temperatures or elevated salinity are less resilient, but
there are no clear thresholds at which this long-term exposure raises
extirpation risk. Thus, our categorization methodology may over- or
under-estimate resiliency of populations depending on the actual
biological thresholds.
A critical assumption is that the primary stressors we identified,
sheepshead minnow presence, and water quality and quantity alteration
that leads to habitat loss and fragmentation, which are exacerbated due
to climate change, are the primary threats to the species' long-term
viability. Although land use practices and development have impacted
the species historically, given the current distribution of Pecos
pupfish populations, we anticipate that these activities would not have
a large future impact.
In order to characterize sheepshead minnow introgression into the
future, we separately assessed this stressor. This stressor is a low
probability, high consequence event where, if the event occurs, a
population could be extirpated or highly degraded. The future scenarios
included climate effects but assumed no change in sheepshead minnow
presence. Both the climate change scenarios and the risk of sheepshead
minnow introgression should be considered when assessing the status of
the species.
Another assumption in this SSA regards the role of conservation in
future viability of the Pecos pupfish.
[[Page 92760]]
With the current conservation agreement in place, the Conservation Team
has been proactive in supporting the species. We incorporated these
efforts into several aspects of our analysis, such as our evaluation of
the probability of current Pecos pupfish populations being invaded by
nonnatives, taking into consideration conservation measures to prevent
such invasion. However, we did not incorporate water conservation
efforts into our future projects. While past water conservation,
particularly in the PVACD, has had beneficial impacts to groundwater
supply within the range of the Pecos pupfish, we were uncertain of the
direct link between these measures and Pecos pupfish habitat. Based on
this, we assume that water conservation efforts that maintain current
aquifer levels, or limit future declines could improve resilience of
Pecos pupfish populations. However, because both the implementation and
success of any water conservation efforts and response of Pecos pupfish
habitat to changing aquifer levels is unknown, were unable to
incorporate this into our analysis. Surface Temperature
Average annual surface temperatures as well as the incidence of
extreme heat events are projected to increase across the entirety of
the Southwest including the Pecos Basin (Vose et al. 2017, entire).
Within the Pecos Basin, average surface temperatures could increase by
as much as 13.32 [deg]F (-10.4 [deg]C) to an average surface
temperature in excess of 70 [deg]F (21.1 [deg]C).
As temperatures increase across the region, we anticipate a
corresponding increase in evapotranspiration rates. Both temperature
and evapotranspiration rates can have negative effects on Pecos pupfish
and their habitat. Increasing temperatures increase the risk of golden
algae blooms as well as increasing the chances that shallow habitat
could exceed the thermal tolerance of Pecos pupfish. Greater
evapotranspiration leads to lowering of water levels with the potential
for corresponding increases in salinity and water temperatures and
lowered dissolved oxygen. Lowered water levels also may lead to a
reduction in the overall habitat available to Pecos pupfish along with
the potential of the complete loss of water in shallow aquatic
environments.
Precipitation and Aquifer Levels
Precipitation changes related to climate change are more variable
and less certain than those changes projected for temperature. In the
Southwest, the occurrence of seasonal monsoons complicates the picture
for overall projected changes to precipitation in the Pecos River
Basin. Though generally models predict a drying trend across the Pecos
Basin, under certain RCP 8.5 conditions, monsoon moisture increases,
leading to an increase in average annual precipitation. Under both RCP
4.5 and RCP 8.5 scenarios, snowpack in the headwater of the Pecos River
decreases with a corresponding earlier snowmelt runoff (Llewellyn et
al. 2021, p. 191). Though precipitation changes could potentially
reduce flows into the San Andres aquifer from the Sacramento Mountains,
the effect of lower snowpack and runoff will likely be most impactful
to the Pecos River.
The level of the San Andres aquifer likely directly impacts the
water sources for most non-riverine Pecos pupfish habitats, except for
those in Salt Creek (TX) (Land 2003, p. 228). Although we do not know
the exact relationship between aquifer levels and the springs that
provide flows to sinkholes, wetlands, and streams that provide Pecos
pupfish habitat, we can infer that changes to the aquifer level will
likely produce a corresponding change in spring flows. Levels in the
San Andres aquifer are influenced by the amount of historical water in
the aquifer and current inputs (Land and Huff 2009, p. 20) as well as
pumping by users in the PVACD.
Future Scenarios
Scenario 1--Hot and Dry (RCP 8.5)
In this scenario, future annual air temperature increases slightly,
and annual precipitation decreases throughout the Pecos River Basin.
Though temperatures increase in all seasons, summer and autumn
temperatures are predicted to increase more than winter and spring
temperatures. By 2100 (and likely much sooner), conditions in the Pecos
River Basin would be much drier than the historical average.
Precipitation would be greatly decreased in all seasons, though
decreases would be most extreme during the monsoon season. Runoff
inflow into the Pecos River Basin will decrease across every season,
and the inflow that will occur is anticipated to be the result of very
few large storm events (Llewellyn et al. 2021, p. 105).
Scenario 2--Hot and Wet (RCP 8.5)
In this scenario, both temperature and annual precipitation
increase throughout the Pecos River Basin. Increased temperatures
retain more moisture in the atmosphere leading to increased monsoons.
This scenario is more seasonally variable, with sharply increased
inflow during the monsoon season and a steep decrease of inflow during
the spring runoff. In this scenario, spring and summer temperatures
increase more rapidly than fall and winter temperatures. While
precipitation decreases during winter and spring, precipitation
increases during the summer and autumn monsoon season, leading to an
overall increase in precipitation within the Pecos River Basin. As a
result of decreased winter precipitation, spring runoff is anticipated
to decrease. However, a large increase in monsoon flows make up for the
spring runoff decrease (Llewellyn et al. 2021, pp. 105-106).
Scenario 3--Warm and Dry (RCP 4.5)
This scenario anticipates the smallest changes to temperature and
precipitation of the three scenarios. By 2100, this scenario predicts
slightly higher average temperatures and a slightly dryer climate.
Importantly, summer and fall temperatures are anticipated to increase
almost twice as much as winter and spring temperatures (Llewellyn et
al. 2021, p. 101).
Future Condition Projections
Using the projections for temperature, precipitation, and San
Andres aquifer under the three scenarios outlined above, we then
predicted the potential range of outcomes these scenarios could have on
the Pecos pupfish. Future conditions were analyzed for each resiliency
metric and summarized for each unit (Service 2024, appendix C, entire).
Scenario 1--Hot and Dry (RCP 8.5)
This scenario forecasts extreme drying and higher temperatures
across the Pecos River Basin. A decrease in precipitation across the
basin along with increased air temperatures and overall drying trends
is projected to lead to decreases in stream flow, spring output, and
potentially a lowering of the aquifer that supports wetland and
sinkhole habitats for the pupfish. Although the Pecos River is managed
for flows that support endangered species such as the Pecos bluntnose
shiner, decreasing precipitation will lead to an increase in drying
days, impeding the ability of the upstream storage to deliver reliable
water to both downstream users and retain adequate flow in the Pecos
River and. Higher temperatures, particularly during the summer, will
lead to an increase in water needs and increased groundwater pumping by
agriculture in the PVACD. Higher temperatures also increase evaporative
loss from water
[[Page 92761]]
bodies and could lead to decreases in habitats available for the
pupfish.
This scenario will have some negative effects on all Pecos pupfish
AUs. The most severe impacts are anticipated to be to small streams.
Salt Creek (TX), Salt Creek (NM), and Bitter Creek are all projected to
dry and cease flowing during the hottest parts of the year leading to
local fish kills, or in the case of Salt Creek (TX), possibly the loss
of all habitats in the AU. All of these creeks currently experience
intermittent drying events, and lower precipitation and increased
temperatures in the future will exacerbate this existing condition that
stresses these habitats. Wetland areas such as the BLM Overflow
Wetlands and the managed wetlands on Bitter Lake NWR are also
anticipated to be significantly impacted in this scenario. At the 2050
timestep, given the climate projections, habitat conditions are
projected to be similar to current conditions with minimal changes to
most aquatic environments, with the exception of small streams that are
already experiencing impacts from warming and drying temperatures. By
2100, significant degradation to Pecos pupfish habitat and a decline in
its distribution are expected. Shallow streams will likely no longer
support permanent water leading to the loss of fish in Bitter Creek,
Salt Creek (NM), and Salt Creek (TX), which would mean the extirpation
of Pecos pupfish from Texas. Habitat extent in wetland habitats in the
BLM Overflow Wetlands and Middle Tract on Bitter Lake NWR will be
greatly reduced, and pupfish would be expected to persist only in
deeper channels or near springs.
Historically, the San Andres aquifer has been resilient and
rebounded after extended drought (Land and Newton 2008, pp. 189-190).
However, the conditions under this scenario, RCP 8.5, at 2100 will be
much hotter and drier than the historical average and are expected to
lead to unprecedented conditions in aquifer levels and surface water
quality and quantity. Across the range of the Pecos pupfish, we
anticipate substantial increases in salinity as a result of increased
evapotranspiration. Although Pecos pupfish can tolerate higher salinity
levels than most fish, significant salinity impairment (salinities
greater than 35,000 mg/L) could lead to a reduction in suitable
conditions for breeding. Increasing surface temperatures will lead to
an increase in water temperatures and likely lowered dissolved oxygen
saturation. This will be particularly pronounced in shallow habitat
such as streams and wetlands. A substantial reduction in the aquifer
level would reduce the outflow of springs leading to a loss of fish in
habitats that rely on steady, perennial spring flow and a reduction (or
elimination) of available habitat in shallower sinkholes. Additionally,
the increasing temperature and evaporation could cause shallower
habitats to exceed the thermal and saline tolerances of the Pecos
pupfish. Consequently, we anticipate a reduction in both the number,
extent, and population sizes of extant sites in sinkhole units.
Finally, we anticipate greatly reduced flows in the Pecos River under
this scenario. While reduced flows in the Pecos River have the
potential to benefit the pupfish on a seasonal basis, long-term drying
events will lead to the disconnection of occupied sites and increased
impairment of water quality.
Given these assumed future changes in the environment, by 2050,
three AUs (Bitter Lake NWR Middle Tract Wetlands, Bottomless Lakes
State Park, and BLM Overflow Wetlands and Lea Lake) are projected to
remain in high condition, three units (Upper Pecos River, Salt Creek
Wilderness, and Bitter Creek Drainage) are in moderate condition, and
one unit (Salt Creek (TX)) is in low condition (Service 2024, p. 83).
At 2100, only one AU (Bottomless Lakes State Park) is in high
condition, four units (Upper Pecos River, Bitter Creek Drainage, Bitter
Lake NWR Middle Tract Wetlands, and BLM Overflow Wetlands and Lea Lake)
are in moderate condition, one unit (Salt Creek Wilderness) is in low
condition, and one AU (Salt Creek (TX)) is extirpated. Although habitat
conditions are expected to generally decline across the range, the
Bottomless Lakes State Park AU is anticipated to remain in high
condition because the sinkhole habitats there are expected to be less
affected by potential aquifer declines. While only two units (Bitter
Creek Drainage and Salt Creek (TX)) experience declines from current
condition at 2050, by 2100 all units except Bottomless Lakes State Park
experience declines from current condition.
Scenario 2--Hot and Wet (RCP 8.5)
This scenario forecasts a significantly higher average annual
surface temperature across the Pecos River Basin. Unlike Scenario 1,
higher summer temperatures result in more moisture in the atmosphere,
consequently leading to an increase in precipitation during the summer
monsoon season (June-September). Overall higher surface temperatures
will lead to similar outcomes as described under Scenario 1, such as
water quality impairment, and reduction in habitat extent. However, the
predicted increased monsoons may buffer some systems from the most
severe impacts of increasing average temperatures.
As with Scenario 1, the small streams are most likely to experience
the most severe adverse impacts from increasing annual temperatures.
These aquatic environments will likely experience more drying events
and subsequent impairments to salinity, water temperatures, and
dissolved oxygen. At the 2050 timestep, conditions appear similar to
current conditions throughout much of the Pecos pupfish range. However,
small streams will likely stop flowing during the hottest parts of the
year, leading to local fish kills, or in the case of Salt Creek (TX),
possibly the loss of all habitats in the AU. By 2100, rising annual
temperatures may eliminate year-round stream flow in all but the
wettest years. Consequently, we anticipate the loss of the Pecos
pupfish population at Salt Creek (TX) and a reduction in occupied sites
in Bitter Creek and the Salt Creek Wilderness. Increased temperatures
will have an impact on shallower wetlands in the BLM Overflow Wetlands
and Bitter Lake NWR Middle Tract Wetlands. Prolonged extreme air
temperatures can adversely impact water quality and could result in
decreased fitness, hinder breeding, or lead to fish kills. Sinkholes
are the most stable environment for the Pecos pupfish, and this is
unlikely to change in this scenario. The San Andres aquifer responds
quickly to precipitation inputs, and an increase in monsoon season
precipitation will likely prevent significant declines in sinkhole
water levels.
Given these assumed future changes in the environment, at 2050,
three units (Bitter Lake NWR Middle Tract Wetlands, Bottomless Lakes
State Park, and BLM Overflow Wetlands and Lea Lake) are projected to
remain in high condition, three units (Upper Pacos River, Salt Creek
Wilderness, and Bitter Creek Drainage) are in moderate condition, one
unit (Salt Creek (TX)) is in low condition, and two units (Middle Pecos
River and Lower Pecos River) remain extirpated. Under this scenario,
only two units (Bitter Creek Drainage and Salt Creek (TX)) experience a
decrease from current condition. At 2100, two units (Bottomless Lakes
State Park and BLM Overflow Wetlands and Lea Lake) are in high
condition, three units (Upper Pecos River, Bitter Creek Drainage, and
Bitter Lake NWR Middle Tract Wetlands) are in moderate condition, one
unit (Salt Creek Wilderness) is in low condition, and three units
(Middle Pecos River, Salt Creek (TX), and Lower Pecos River) are
[[Page 92762]]
extirpated, with all units except Upper Pecos River, Bottomless Lakes
State Park, and BLM Overflow Wetlands and Lea Lake experiencing a
decrease from current condition.
Scenario 3--Warm and Dry (RCP 4.5)
This scenario forecasts a minimal increase in yearly average
temperatures and a minimal decrease in precipitation across the basin.
Even minimal decreases in precipitation could have consequences for
shallow streams in several units (Salt Creek Wilderness, Bitter Creek
Drainage, and Salt Creek (TX)). Like the prior scenarios, the 2050 time
step appears fairly similar to current condition. By 2100, small
streams are likely experiencing increased water stress, and in dry
years likely most of the stream environments will be dry. However,
under this scenario, we anticipate minimal impacts to groundwater
resources and thus minimal impacts to sinkhole, spring fed, and river
habitats.
At 2050, four units (Bitter Creek Drainage, Bitter Lake NWR Middle
Tract Wetlands, Bottomless Lakes State Park, and BLM Overflow Wetlands
and Lea Lake) are projected to be in high condition, and three units
(Upper Pecos River, Salt Creek Wilderness, and Salt Creek (TX)) are in
moderate condition, and two units (Middle Pecos River and Lower Pecos
River) are extirpated. At 2100, three units (Bitter Lake NWR Middle
Tract Wetlands, Bottomless Lakes State Park, and BLM Overflow Wetlands
and Lea Lake) are projected to be in high condition, three units (Upper
Pecos River, Salt Creek Wilderness, and Bitter Creek Drainage) are in
moderate condition, one unit (Salt Creek (TX)) is in low condition, and
two units (Middle Pecos River and Lower Pecos River) are extirpated. In
Scenario 3, no units experience decreases from current condition at
2050; however, at 2100 two units (Bitter Creek Drainage and Salt Creek
(TX)) experience decreases from current condition.
Sheepshead Minnow
Along with the three scenarios described above, we also considered
the risk of sheepshead minnow introgression into the different AUs.
Because sheepshead minnow are often used as bait fish, the most likely
path for the sheepshead minnow to move into units existing with non-
introgressed Pecos pupfish populations is through a bait bucket
transfer into the Pecos River upstream of Brantley Reservoir. Based on
data collected from the lower Pecos River, this scenario would be
highly likely to result in the introgression of the entire population
of Pecos pupfish in the Pecos River (Unit 1, Upper Pecos River)
(Whiteley 2023, p. 2). Bait bucket transfers are highly unlikely to
occur in any of the other AUs, as these units are generally either well
controlled or do not contain game fish species. As such, the most
likely route for sheepshead minnow introgression into other AUs would
be natural movement of sheepshead minnow from the Upper Pecos River AU,
if they gained access there.
The AUs most at risk of sheepshead minnow introgression from the
upper Pecos River are the Salt Creek Wilderness and Middle Tract
Wetlands, which are both connected hydrologically to the upper Pecos
River during flooding events, allowing for potential movement of
sheepshead minnow into these off-channel habitats. In the case of the
Salt Creek Wilderness, only Salt Creek (NM) itself is vulnerable to
sheepshead minnow invasion, as the isolated sink holes in that AU are
not likely to be inundated during Pecos River flooding events. Because
of the managed nature of the Middle Tract Wetlands by the Bitter Lake
NWR staff and the existence of numerous water control structures that
can reduce opportunities for fish movement, the vulnerability within
the unit decreases with distance from the Pecos River. Managed water
flows, manmade barriers, and direct human intervention would likely be
employed to manage the spread of sheepshead minnow throughout the unit
if the species were to gain access to the Upper Pecos River. The lower
portion of Salt Creek (TX) is already introgressed with sheepshead
minnow; however, despite the lack of a clear barrier preventing
upstream movement, upstream portions of the stream have maintained non-
introgressed pupfish. Because we cannot identify a barrier, we assume
the risk of introgression remains high. The remaining three units
adjacent to the Pecos River (Salt Creek Wilderness, Bitter Creek
Drainage, and Bottomless Lakes State Park) have either manmade or
natural barriers that would prevent or minimize the chance of the
spread of sheepshead minnow from the Pecos River into these units,
resulting in low introgression risk.
Assessment of Future Viability
We considered what the Pecos pupfish needs to maintain viability
and characterized the status of the species in terms of its resiliency,
redundancy, and representation. For the purpose of this assessment, we
define viability as the ability of the species to sustain populations
in natural ecosystems within a biologically meaningful timeframe: in
this case, out to 2100. We chose 2100 because we have information to
reasonably project the potential significant effects of stressors
within the range of the Pecos pupfish within this timeframe. Based on
the Pecos pupfish life history and habitat needs, and in consultation
with the species' experts, we identified the potential stressors
(negative influences), and the contributing sources of those stressors,
that are likely to affect the species' future viability. We then
evaluated how these potential future stressors would interact with
current stressors, and how, and to what extent they would affect the
species in the future. Based on the best available information, we
believe the two largest influences on the future viability of the Pecos
pupfish are the potential of introgression with sheepshead minnow and
climate change-driven impacts to water quantity, water quality, and
loss of habitat diversity. While water pollution and human development
(particularly agricultural and oil and gas development) activities have
likely influenced the species' current condition and may affect some
areas (Salt Creek (TX)) in the future, we found that the changing
climate and the related effects to water availability to sustain
habitats has, and will continue to have, the greatest influence on the
status of the Pecos pupfish. Sheepshead minnow introduction, while much
less predictable, does have the potential to impact Pecos pupfish
populations above Brantley Dam should an introduction occur.
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have
analyzed the cumulative effects of identified threats and conservation
actions on the species. To assess the current and future condition of
the species, we evaluate the effects of all the relevant factors that
may be influencing the species, including threats and conservation
efforts. Because the SSA framework considers not just the presence of
the factors, but to what degree they collectively influence risk to the
entire species, our assessment integrates the cumulative effects of the
factors and replaces a standalone cumulative-effects analysis.
Determination of Pecos Pupfish Status
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an endangered species or a
threatened species. The Act defines an ``endangered species'' as a
species in
[[Page 92763]]
danger of extinction throughout all or a significant portion of its
range, and a ``threatened species'' as a species likely to become an
endangered species within the foreseeable future throughout all or a
significant portion of its range. The Act requires that we determine
whether a species meets the definition of an endangered species or a
threatened species because of any of the following factors: (A) The
present or threatened destruction, modification, or curtailment of its
habitat or range; (B) overutilization for commercial, recreational,
scientific, or educational purposes; (C) disease or predation; (D) the
inadequacy of existing regulatory mechanisms; or (E) other natural or
manmade factors affecting its continued existence.
Status Throughout All of Its Range
Our assessment of best available information indicates that
currently two of the nine known Pecos pupfish populations have been
extirpated, and three others are in moderate condition. The majority of
known occupied Pecos pupfish sites are within the other five units
around Bitter Lake NWR and Bottomless Lakes State Park in New Mexico
(AUs 2-6). Within these units, four were found to be in high condition
and one in moderate condition, indicating that multiple areas across
the species' core range have high resiliency. The small Salt Creek AU
in Texas is currently in moderate condition. This unit is disconnected
from the remainder of the species' range in New Mexico, providing some
redundancy in maintaining a relatively large geographic range. The two
large units of the Lower and Middle Pecos River have been previously
extirpated due to the introgression of the sheepshead minnow. Loss of
these parts of the range represent a significant reduction in the
overall range and redundancy for the species and loss of a large
segment of the riverine habitats historically available to the species.
The riverine habitats continue to be represented by the Upper Pecos
River Unit.
Under all three plausible future scenarios, species condition would
be reduced by 2100. In the hottest and driest scenario (Scenario 1),
shallow streams are likely to be lost, leading to the extirpation of
Pecos pupfish in Salt Creek (TX) and a reduction in redundancy and
representation in the Salt Creek Wilderness and Bitter Creek Drainage
units. Deeper sinkholes and wetlands are more stable and are expected
to maintain suitable conditions for the Pecos pupfish under all
scenarios. However, units such as Bitter Creek Drainage, Middle Tract,
and BLM Overflow Wetlands are more vulnerable to losses in redundancy
in Scenario 1 due to susceptibility to habitat losses from future
drying climatic conditions. The Pecos River may also be unable to
sustain year-round flows under conditions predicted in Scenario 1. The
increased stream flows from projected increase in monsoons in Scenario
2 help maintain sinkhole habitats throughout the range of the Pecos
pupfish, and to a lesser extent, likely may buffer wetland habitats
from the most severe impacts of increased temperatures. However, small
streams are likely still at elevated risk of being lost or experiencing
long-term drying or mortality events. Finally, in the mildest future
climate scenario (Scenario 3), further effects to most habitat
(wetlands, sinkholes, and riverine) are anticipated to be minimal.
However, like the other two scenarios, shallow streams likely will
experience drying and mortality events.
Under all three scenarios, we anticipate some reductions to
resilience, redundance, and representation. Although some additional
changes to Pecos pupfish status are projected to occur by 2050, we
anticipate that measurable changes to viability will be more apparent
by 2100. The resilience of the aquifer to small year-to-year variation
and the adaptability of the Pecos pupfish to variable habitat
conditions will likely offset some of the climate changes through 2050.
Under all scenarios, at least one AU remains in high condition. Under
both Scenarios 1 and 2, Pecos pupfish are projected to be extirpated
from Salt Creek (TX), eliminating the only population outside of New
Mexico that has been described as genetically different from the core
populations in New Mexico. Pecos pupfish experience most losses of
known occupied sites under Scenario 1, though losses would be likely to
occur under scenarios 2 and 3 as well. Bottomless Lakes State Park
remains the only AU that would be in high condition under all three
scenarios.
Concurrent with the effects of climate change is the risk of
expansion of sheepshead minnow and subsequent hybridization with Pecos
pupfish. Salt Creek (TX) is already at high risk of loss due to
sheepshead minnow introgression. The Upper Pecos River is currently
highly vulnerable to sheepshead minnow introduction via a bait bucket
transfer. Should this introduction occur, non-introgressed Pecos
pupfish would likely be extirpated from this unit, and, as a
consequence there would be no remaining Pecos pupfish in the Pecos
River. This would also increase the potential for sheepshead minnow
invasion into portions of the Salt Creek Wilderness, the Middle Tract
Wetlands, and possibly the Overflow Wetlands units.
The Pecos Pupfish Conservation Agreement will continue to provide
guidance for agencies and partners working toward Pecos pupfish
conservation through several means. First, the monitoring outlined in
the conservation agreement will provide a long-term data set on the
persistence of Pecos pupfish and, as methods are refined, population
trends within four AUs (Bitter Creek Drainage and Bitter Lake NWR
Middle Tract Wetlands, BLM Overflow Wetlands and Lea Lake, and
Bottomless Lakes State Park). This monitoring will allow partners to
detect potential sheepshead minnow introgression and allow for the
detection of long-term declines or extirpations of Pecos pupfish.
Secondly, the conservation agreement will help provide for ongoing
maintenance (or potentially additional) barriers to fish passage that
may protect some of the AUs from sheepshead minnow introgression should
a bait bucket transfer into the Upper Pecos River occur. Finally, the
agreement can reduce the opportunity for further invasions by a
collaborative effort of State and Federal entities to enforce existing
baitfish regulations.
After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we find that Pecos pupfish populations will continue to face
the ongoing risk of sheepshead minnow introgression, and populations
will remain small and isolated from one another. The risk of sheepshead
minnow introgression is cumulative, meaning that the risk builds over
time such that the risk of this species being introduced into the
current Pecos pupfish range by a bait bucket transfer is higher in the
future than it is currently. Additionally, Pecos pupfish populations
will experience reductions in resiliency, redundance, and
representation through 2050, with more measurable declines by 2100 due
to decreased surface water availability, increased frequency of
drought, higher than average temperatures, and continued groundwater
depletion.
We considered whether the Pecos pupfish is presently in danger of
extinction and determined that endangered status is not appropriate.
The current conditions assessed in the SSA report show that the Pecos
pupfish is distributed across seven of nine AUs across the historical
range. Although there may have been reductions from
[[Page 92764]]
the historical range and population sizes, monitoring data indicate
that the Pecos pupfish continues to have multiple, long-term,
persistent populations throughout the range. Currently only two of the
seven AUs are at high risk for sheepshead minnow introgression, and
four AUs are not subjected to declines in water quantity. While threats
are currently acting on the species and many of those threats are
expected to continue into the future, we did not find that the species
is currently in danger of extinction throughout all of its range. We
believe the demand on water in the Pecos River Basin is expected to
increase based on climate change projections (Sites Southwest 2008, pp.
6-3, 6-6), but adequate aquifer levels may be maintained until 2100
(Llewellyn et al. 2021, p. 100). Thus, after assessing the best
available information, we conclude that the Pecos pupfish is not in
danger of extinction but is likely to become in danger of extinction
within the foreseeable future throughout all of its range.
Status Throughout a Significant Portion of Its Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. The court in Center for Biological Diversity v. Everson, 435
F. Supp. 3d 69 (D.D.C. 2020) (Everson), vacated the provision of the
Final Policy on Interpretation of the Phrase ``Significant Portion of
Its Range'' in the Endangered Species Act's Definitions of ``Endangered
Species'' and ``Threatened Species'' (hereafter ``Final Policy''; 79 FR
37578, July 1, 2014) that provided if the Services determine that a
species is threatened throughout all of its range, the Services will
not analyze whether the species is endangered in a significant portion
of its range.
Therefore, we proceed to evaluating whether the species is
endangered in a significant portion of its range--that is, whether
there is any portion of the species' range for which both (1) the
portion is significant; and (2) the species is in danger of extinction
in that portion. Depending on the case, it might be more efficient for
us to address the ``significance'' question or the ``status'' question
first. We can choose to address either question first. Regardless of
which question we address first, if we reach a negative answer with
respect to the first question that we address, we do not need to
evaluate the other question for that portion of the species' range.
Following the court's holding in Everson, we now consider whether
the species is in danger of extinction in a significant portion of its
range. In undertaking this analysis for Pecos pupfish, we choose to
address the status question first.
We evaluated the range of the Pecos pupfish to determine if the
species is in danger of extinction in any portion of its range. The
range of a species can theoretically be divided into portions in an
infinite number of ways. We focused our analysis on portions of the
species' range that may meet the definition of an endangered species.
For Pecos pupfish, we considered whether the threats or their effects
on the species are greater in any biologically meaningful portion of
the species' range than in other portions such that the species is in
danger of extinction in that portion.
We examined the range for biologically meaningful portions based on
the four broad categories of aquatic environments that Pecos pupfish
occupy throughout its range, which reflect phylogenic relationships as
well as physiogeographical differences in aquatic habitat. The aquatic
environments germane to the range of the Pecos pupfish are riverine
(includes the upper, middle, and lower Pecos River segments), shallow
stream (includes Salt Creek (NM) and Salt Creek (TX)), sinkholes
(includes Salt Creek Wilderness, Bitter Creek Drainage, and Bottomless
Lakes State Park), and wetlands (includes Bitter Creek Middle Tract
Wetlands and BLM Overflow Wetlands and Lea Lake).
Once we identified the biologically meaningful portions to examine,
we then turned to the question of whether these portions may have a
different biological status. Of these aquatic environments, the
riverine environment contains just one population, the upper Pecos
River, which is in moderate condition. The other environments have
multiple populations, including four in high condition. Therefore, we
are examining the riverine environment to determine if it has a
different status than the remainder of the range.
We evaluated the available information about this portion of the
range of Pecos pupfish that occupies the upper Pecos River in this
context, assessing its biological significance in terms of condition
criteria (genetic security, occurrence, water quality, water quantity,
and habitat diversity; see Current Condition) used to assign the
current condition of Pecos pupfish populations. While the entire Pecos
River is characterized as a sometimes fairly shallow and meandering
riverine habitat with ephemeral tributaries, the primary risk to the
upper Pecos River population is the introduction of sheepshead minnow.
The single population in this aquatic habitat is also affected by
severe low flow or no flow events and intermittency, as well as water
quality impairments. Sheepshead minnow were introduced to portions of
the Pecos River in the 1980s; Brantley Dam currently serves as a
barrier to prevent sheepshead minnow from naturally moving north into
the upper Pecos River. Because sheepshead minnow are often used as bait
fish, the most likely path for the sheepshead minnow to move into non-
introgressed Pecos pupfish populations is through a bait bucket
transfer into the Pecos River upstream of Brantley Reservoir. At that
point, sheepshead minnow could naturally spread from the upper Pecos
River to additional Pecos pupfish populations. Because the risk of
introduction of sheepshead minnow is equal across all habitat types and
is the primary reason that we found the Pecos pupfish to be threatened
rangewide, there is not a difference in risk that would cause the upper
Pecos River to have a different status than the remainder of the range.
Therefore, no portion of the species' range provides a basis for
determining that the species is in danger of extinction in a
significant portion of its range, and we determine that the species is
likely to become in danger of extinction within the foreseeable future
throughout all of its range. This does not conflict with the courts'
holdings in Desert Survivors v. U.S. Department of the Interior, 321 F.
Supp. 3d 1011, 1070-74 (N.D. Cal. 2018) and Center for Biological
Diversity v. Jewell, 248 F. Supp. 3d 946, 959 (D. Ariz. 2017) because,
in reaching this conclusion, we did not apply the aspects of the Final
Policy, including the definition of ``significant'' that those court
decisions held to be invalid.
Determination of Status
Based on of the best scientific and commercial data available, we
determine that the Pecos pupfish meets the Act's definition of a
threatened species. Therefore, we propose to list the Pecos pupfish as
a threatened species in accordance with sections 3(20) and 4(a)(1) of
the Act.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition as a listed
species, planning and implementation of recovery actions, requirements
for Federal protection, and prohibitions against certain practices.
Recognition through listing results in public
[[Page 92765]]
awareness, and conservation by Federal, State, Tribal, and local
agencies, foreign governments, private organizations, and individuals.
The Act encourages cooperation with the States and other countries and
calls for recovery actions to be carried out for listed species. The
protection required by Federal agencies, including the Service, and the
prohibitions against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Section 4(f) of the Act calls for the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The goal of this process is to restore listed
species to a point where they are secure, self-sustaining, and
functioning components of their ecosystems.
The recovery planning process begins with development of a recovery
outline made available to the public soon after a final listing
determination. The recovery outline guides the immediate implementation
of urgent recovery actions while a recovery plan is being developed.
Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) may be
established to develop and implement recovery plans. The recovery
planning process involves the identification of actions that are
necessary to halt and reverse the species' decline by addressing the
threats to its survival and recovery. The recovery plan identifies
recovery criteria for review of when a species may be ready for
reclassification from endangered to threatened (``downlisting'') or
removal from protected status (``delisting''), and methods for
monitoring recovery progress. Recovery plans also establish a framework
for agencies to coordinate their recovery efforts and provide estimates
of the cost of implementing recovery tasks. Revisions of the plan may
be done to address continuing or new threats to the species, as new
substantive information becomes available. The recovery outline, draft
recovery plan, final recovery plan, and any revisions will be available
on our website as they are completed (<a href="https://www.fws.gov/program/endangered-species">https://www.fws.gov/program/endangered-species</a>), or from our New Mexico Ecological Services Field
Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If this species is listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost-share grants for non-Federal landowners, the
academic community, and nongovernmental organizations. In addition,
pursuant to section 6 of the Act, the State(s) of New Mexico and Texas
would be eligible for Federal funds to implement management actions
that promote the protection or recovery of the Pecos pupfish.
Information on our grant programs that are available to aid species
recovery can be found at: <a href="https://www.fws.gov/service/financial-assistance">https://www.fws.gov/service/financial-assistance</a>.
Although the Pecos pupfish is only proposed for listing under the
Act at this time, please let us know if you are interested in
participating in recovery efforts for this species. Additionally, we
invite you to submit any new information on this species whenever it
becomes available and any information you may have for recovery
planning purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7 of the Act is titled Interagency Cooperation and mandates
all Federal action agencies to use their existing authorities to
further the conservation purposes of the Act and to ensure that their
actions are not likely to jeopardize the continued existence of listed
species or adversely modify critical habitat. Regulations implementing
section 7 are codified at 50 CFR part 402.
Section 7(a)(2) states that each Federal action agency shall, in
consultation with the Secretary, ensure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse
modification of designated critical habitat. Each Federal agency shall
review its action at the earliest possible time to determine whether it
may affect listed species or critical habitat. If a determination is
made that the action may affect listed species or critical habitat,
formal consultation is required (50 CFR 402.14(a)), unless the Service
concurs in writing that the action is not likely to adversely affect
listed species or critical habitat. At the end of a formal
consultation, the Service issues a biological opinion, containing its
determination of whether the federal action is likely to result in
jeopardy or adverse modification.
In contrast, section 7(a)(4) of the Act requires Federal agencies
to confer with the Service on any action which is likely to jeopardize
the continued existence of any species proposed to be listed under the
Act or result in the destruction or adverse modification of critical
habitat proposed to be designated for such species. Although the
conference procedures are required only when an action is likely to
result in jeopardy or adverse modification, action agencies may
voluntarily confer with the Service on actions that may affect species
proposed for listing or critical habitat proposed to be designated. In
the event that the subject species is listed or the relevant critical
habitat is designated, a conference opinion may be adopted as a
biological opinion and serve as compliance with section 7(a)(2).
Examples of discretionary actions for the Pecos pupfish that may be
subject to conference and consultation procedures under section 7 are
management of Federal lands administered by the BLM, the BOR, the
Corps, and the Service's NWR System as well as actions that require a
Federal permit (such as a permit from the Corps under section 404 of
the Clean Water Act (33 U.S.C. 1251 et seq.) or actions funded be
Federal agencies such as the Federal Highway Administration, Federal
Aviation Administration, or the Federal Emergency Management Agency.
Federal actions not affecting listed species or critical habitat--and
actions on State, Tribal, local, or private lands that are not
federally funded, authorized, or carried out by a Federal agency--do
not require section 7 consultation. Federal agencies should coordinate
with the New Mexico Ecological Services Field Office (see FOR FURTHER
INFORMATION CONTACT) with any specific questions on section 7
consultation and conference requirements.
II. Protective Regulations Under Section 4(d) of the Act
Background
Section 4(d) of the Act contains two sentences. The first sentence
states that the Secretary shall issue such regulations as she deems
necessary and advisable to provide for the
[[Page 92766]]
conservation of species listed as threatened species. Conservation is
defined in the Act to mean the use of all methods and procedures which
are necessary to bring any endangered species or threatened species to
the point at which the measures provided pursuant to the Act are no
longer necessary. Additionally, the second sentence of section 4(d) of
the Act states that the Secretary may by regulation prohibit with
respect to any threatened species any act prohibited under section
9(a)(1), in the case of fish or wildlife, or section 9(a)(2), in the
case of plants. With these two sentences in section 4(d), Congress
delegated broad authority to the Secretary to determine what
protections would be necessary and advisable to provide for the
conservation of threatened species, and even broader authority to put
in place any of the section 9 prohibitions, for a given species.
The courts have recognized the extent of the Secretary's discretion
under this standard to develop rules that are appropriate for the
conservation of a species. For example, courts have upheld, as a valid
exercise of agency authority, rules developed under section 4(d) that
included limited prohibitions against takings (see Alsea Valley
Alliance v. Lautenbacher, 2007 WL 2344927 (D. Or. 2007); Washington
Environmental Council v. National Marine Fisheries Service, 2002 WL
511479 (W.D. Wash. 2002)). Courts have also upheld 4(d) rules that do
not address all of the threats a species faces (see State of Louisiana
v. Verity, 853 F.2d 322 (5th Cir. 1988)). As noted in the legislative
history when the Act was initially enacted, ``once an animal is on the
threatened list, the Secretary has an almost infinite number of options
available to [her] with regard to the permitted activities for those
species. [She] may, for example, permit taking, but not importation of
such species, or [she] may choose to forbid both taking and importation
but allow the transportation of such species'' (H.R. Rep. No. 412, 93rd
Cong., 1st Sess. 1973).
The provisions of this species' proposed protective regulations
under section 4(d) of the Act are one of many tools that we would use
to promote the conservation of the Pecos pupfish. The proposed
protective regulations would apply only if and when we make final the
listing of the Pecos pupfish as a threatened species. Nothing in 4(d)
rules change in any way the recovery planning provisions of section
4(f) of the Act, the consultation requirements under section 7 of the
Act, or the ability of the Service to enter into partnerships for the
management and protection of the Pecos pupfish. As mentioned previously
in Available Conservation Measures, section 7(a)(2) of the Act requires
Federal agencies, including the Service, to ensure that any action they
authorize, fund, or carry out is not likely to jeopardize the continued
existence of any endangered species or threatened species or result in
the destruction or adverse modification of designated critical habitat
of such species. In addition, even before the listing of any species or
the designation of its critical habitat is finalized, section 7(a)(4)
of the Act requires Federal agencies to confer with the Service on any
agency action which is likely to jeopardize the continued existence of
any species proposed to be listed under the Act or result in the
destruction or adverse modification of critical habitat proposed to be
designated for such species. These requirements are the same for a
threatened species regardless of what is included in its 4(d) rule.
Section 7 consultation is required for Federal actions that ``may
affect'' a listed species regardless of whether take caused by the
activity is prohibited or excepted by a 4(d) rule (under application of
a ``blanket rule'' (for more information, see 89 FR 23919, April 5,
2024) or a species-specific 4(d) rule). A 4(d) rule does not change the
process and criteria for informal or formal consultations and does not
alter the analytical process used for biological opinions or
concurrence letters. For example, as with an endangered species, if a
Federal agency determines that an action is ``not likely to adversely
affect'' a threatened species, this will require the Service's written
concurrence (50 CFR 402.13(c)). Similarly, if a Federal agency
determines that an action is ``likely to adversely affect'' a
threatened species, the action will require formal consultation with
the Service and the formulation of a biological opinion (50 CFR
402.14(a)). Because consultation obligations and processes are
unaffected by 4(d) rules, we may consider developing tools to
streamline future intra-Service and inter-agency consultations for
actions that result in forms of take that are not prohibited by the
4(d) rule (but that still require consultation). These tools may
include consultation guidance, online consultation processes via the
Service's digital project planning tool (Information for Planning and
Consultation; <a href="https://ipac.ecosphere.fws.gov/">https://ipac.ecosphere.fws.gov/</a>), template language for
biological opinions, or programmatic consultations.
Exercising the Secretary's authority under section 4(d) of the Act,
we propose to apply the protections for the Pecos pupfish through our
regulations at 50 CFR 17.31(a). In our April 5, 2024, final rule
revising those regulations (89 FR 23919 at 23922-23923), we found that
applying those regulations as a whole satisfies the requirement in
section 4(d) of the Act to issue regulations deemed necessary and
advisable to provide for the conservation of the threatened species. We
have not identified any ways in which a protective regulation for this
threatened species would need to differ from the regulations at 50 CFR
17.31(a) in order to contain the protections that are necessary and
advisable to provide for the conservation of the Pecos pupfish.
Therefore, if we finalize this rule as proposed, the regulations at 50
CFR 17.31(a) apply. This means that except as provided in 50 CFR 17.4
through 17.8, or in a permit issued pursuant to 50 CFR 17.32, all of
the provisions of 50 CFR 17.21 for endangered wildlife, except Sec.
17.21(c)(3) and (5), would apply to the Pecos pupfish, and the
provisions of 50 CFR 17.32(b) concerning exceptions for certain
entities would also apply to the species.
Provisions of the Proposed 4(d) Rule
Exercising the Secretary's authority under section 4(d) of the Act,
we have developed a proposed rule that is designed to address the Pecos
pupfish's conservation needs. As discussed previously in Summary of
Biological Status and Threats, we have concluded that the Pecos pupfish
is likely to become in danger of extinction within the foreseeable
future primarily due to risk of introduction of nonnative invasive
sheepshead minnow into new locations occupied by Pecos pupfish, loss
and declines of surface and ground water, degradation of water quality,
and habitat loss and fragmentation. Section 4(d) requires the Secretary
to issue such regulations as she deems necessary and advisable to
provide for the conservation of each threatened species and authorizes
the Secretary to include among those protective regulations any of the
prohibitions that section 9(a)(1) of the Act prescribes for endangered
species. We are not required to make a ``necessary and advisable''
determination when we apply or do not apply specific section 9
prohibitions to a threatened species (In re: Polar Bear Endangered
Species Act Listing and 4(d) Rule Litigation, 818 F. Supp. 2d 214, 228
(D.D.C. 2011) (citing Sweet Home Chapter of Communities for a Great
Oregon v. Babbitt, 1 F.3d 1, 8 (D.C. Cir. 1993), rev'd on other
grounds, 515 U.S. 687 (1995))). Nevertheless, even though
[[Page 92767]]
we are not required to make such a determination, we have chosen to be
as transparent as possible and explain below why we find that, if
finalized, the protections, prohibitions, and exceptions in this
proposed rule as a whole satisfy the requirement in section 4(d) of the
Act to issue regulations deemed necessary and advisable to provide for
the conservation of the Pecos pupfish.
The protective regulations we are proposing for Pecos pupfish
incorporate prohibitions from section 9(a)(1) to address the threats to
the species. The prohibitions of section 9(a)(1) of the Act, and
implementing regulations codified at 50 CFR 17.21, make it illegal for
any person subject to the jurisdiction of the United States to commit,
to attempt to commit, to solicit another to commit or to cause to be
committed any of the following acts with regard to any endangered
wildlife: (1) import into, or export from, the United States; (2) take
(which includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect) within the United States, within the territorial
sea of the United States, or on the high seas; (3) possess, sell,
deliver, carry, transport, or ship, by any means whatsoever, any such
wildlife that has been taken illegally; (4) deliver, receive, carry,
transport, or ship in interstate or foreign commerce, by any means
whatsoever and in the course of commercial activity; or (5) sell or
offer for sale in interstate or foreign commerce. This protective
regulation includes all of these prohibitions because the Pecos pupfish
is at risk of extinction in the foreseeable future and putting these
prohibitions in place will help to prevent further declines, preserve
the species' remaining populations, slow its rate of decline, and
decrease synergistic, negative effects from other ongoing or future
threats.
In particular, this proposed 4(d) rule would provide for the
conservation of the Pecos pupfish by prohibiting the following
activities, unless they fall within specific exceptions or are
otherwise authorized or permitted: importing or exporting; take;
possession and other acts with unlawfully taken specimens; delivering,
receiving, carrying, transporting, or shipping in interstate or foreign
commerce in the course of commercial activity; or selling or offering
for sale in interstate or foreign commerce.
Under the Act, ``take'' means to harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect, or to attempt to engage in any
such conduct. Some of these provisions have been further defined in
regulations at 50 CFR 17.3. Take can result knowingly or otherwise, by
direct and indirect impacts, intentionally or incidentally. Regulating
take would help preserve the species' remaining populations, slow their
rate of decline, and decrease cumulative effects from other ongoing or
future threats. Therefore, we propose to prohibit take of the Pecos
pupfish, except for take resulting from those actions and activities
specifically excepted by the 4(d) rule.
Exceptions to the prohibition on take would include all of the
general exceptions to the prohibition on take of endangered wildlife,
as set forth in 50 CFR 17.21.
Despite these prohibitions regarding threatened species, we may
under certain circumstances issue permits to carry out one or more
otherwise-prohibited activities, including those described above. The
regulations that govern permits for threatened wildlife state that the
Director may issue a permit authorizing any activity otherwise
prohibited with regard to threatened species. These include permits
issued for the following purposes: for scientific purposes, to enhance
propagation or survival, for economic hardship, for zoological
exhibition, for educational purposes, for incidental taking, or for
special purposes consistent with the purposes of the Act (50 CFR
17.32). The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
In addition, to further the conservation of the species, any
employee or agent of the Service, any other Federal land management
agency, the National Marine Fisheries Service, a State conservation
agency, or a federally recognized Tribe, who is designated by their
agency or Tribe for such purposes, may, when acting in the course of
their official duties, take threatened wildlife without a permit if
such action is necessary to: (i) Aid a sick, injured, or orphaned
specimen; or (ii) dispose of a dead specimen; or (iii) salvage a dead
specimen that may be useful for scientific study; or (iv) remove
specimens that constitute a demonstrable but nonimmediate threat to
human safety, provided that the taking is done in a humane manner; the
taking may involve killing or injuring only if it has not been
reasonably possible to eliminate such threat by live-capturing and
releasing the specimen unharmed, in an appropriate area.
We recognize the special and unique relationship that we have with
our State natural resource agency partners in contributing to
conservation of listed species. State agencies often possess scientific
data and valuable expertise on the status and distribution of
endangered, threatened, and candidate species of wildlife and plants.
State agencies, because of their authorities and their close working
relationships with local governments and landowners, are in a unique
position to assist us in implementing all aspects of the Act. In this
regard, section 6 of the Act provides that we must cooperate to the
maximum extent practicable with the States in carrying out programs
authorized by the Act. Therefore, any qualified employee or agent of a
State conservation agency that is a party to a cooperative agreement
with us in accordance with section 6(c) of the Act, who is designated
by his or her agency for such purposes, would be able to conduct
activities designed to conserve Pecos pupfish that may result in
otherwise prohibited take without additional authorization.
The proposed 4(d) rule would also provide for the conservation of
the species by allowing exceptions that incentivize conservation
actions or that, while they may have some minimal impact on the Pecos
pupfish, are not expected to rise to the level that would have a
negative impact (i.e., would have only de minimis impacts) on the
species' conservation. The exceptions to these prohibitions include
incidental and intentional take (described below) that are expected to
have negligible impacts to the Pecos pupfish and its habitat.
Those exceptions include the following activities:
(1) Management and maintenance of ponds that are stocked with
captive-bred Pecos pupfish by the State of Texas.
(2) Research activities on individual Pecos pupfish in those ponds
by holders of a valid State-issued scientific research permit,
zoological permit, or educational display permit. Individuals
exercising this exception must provide to the State of Texas annual
reports containing the following information: the nature of research
performed; dates of fieldwork; the number of individuals collected or
captured, and the methods used to obtain them; a description of any
accidental injuries or mortalities; the number of individuals from
which genetic material was collected, the type of tissue collected, and
the institution or location where the genetic material is being stored.
The location of fieldwork and landowner identifying information is not
required. This exception applies only to individuals with a current,
valid permit from the State of Texas and applies only to research
conducted on pupfish ponds on private lands that are
[[Page 92768]]
part of the TPWD Pecos pupfish production pond effort. The State of
Texas must provide annual reports to the Service regarding use of this
exception.
III. Critical Habitat
Background
Section 4(a)(3) of the Act requires that, to the maximum extent
prudent and determinable, we designate a species' critical habitat
concurrently with listing the species. Critical habitat is defined in
section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features
(a) Essential to the conservation of the species, and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Our regulations at 50 CFR 424.02 define the geographical area
occupied by the species as an area that may generally be delineated
around species' occurrences, as determined by the Secretary (i.e.,
range). Such areas may include those areas used throughout all or part
of the species' life cycle, even if not used on a regular basis (e.g.,
migratory corridors, seasonal habitats, and habitats used periodically,
but not solely by vagrant individuals).
Conservation, as defined under section 3 of the Act, means to use
and the use of all methods and procedures that are necessary to bring
an endangered or threatened species to the point at which the measures
provided pursuant to the Act are no longer necessary. Such methods and
procedures include, but are not limited to, all activities associated
with scientific resources management such as research, census, law
enforcement, habitat acquisition and maintenance, propagation, live
trapping, and transplantation, and, in the extraordinary case where
population pressures within a given ecosystem cannot be otherwise
relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act
through the requirement that each Federal action agency ensure, in
consultation with the Service, that any action they authorize, fund, or
carry out is not likely to result in the destruction or adverse
modification of designated critical habitat. The designation of
critical habitat does not affect land ownership or establish a refuge,
wilderness, reserve, preserve, or other conservation area. Such
designation also does not allow the government or public to access
private lands. Such designation does not require implementation of
restoration, recovery, or enhancement measures by non-Federal
landowners. Rather, designation requires that, where a landowner
requests Federal agency funding or authorization for an action that may
affect an area designated as critical habitat, the Federal agency
consult with the Service under section 7(a)(2) of the Act. If the
action may affect the listed species itself (such as for occupied
critical habitat), the Federal agency would have already been required
to consult with the Service even absent the designation because of the
requirement to ensure that the action is not likely to jeopardize the
continued existence of the species. Even if the Service were to
conclude after consultation that the proposed activity is likely to
result in destruction or adverse modification of the critical habitat,
the Federal action agency and the landowner are not required to abandon
the proposed activity, or to restore or recover the species; instead,
they must implement ``reasonable and prudent alternatives'' to avoid
destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographical area occupied by the species at the time
it was listed are included in a critical habitat designation if they
contain physical or biological features (1) which are essential to the
conservation of the species and (2) which may require special
management considerations or protection. For these areas, critical
habitat designations identify, to the extent known using the best
scientific data available, those physical or biological features that
are essential to the conservation of the species (such as space, food,
cover, and protected habitat).
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographical
area occupied by the species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species.
Section 4(b)(2) of the Act requires that we designate critical
habitat on the basis of the best scientific data available. Further,
our Policy on Information Standards Under the Endangered Species Act
(published in the Federal Register on July 1, 1994 (59 FR 34271)), the
Information Quality Act (section 515 of the Treasury and General
Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554;
H.R. 5658)), and our associated Information Quality Guidelines provide
criteria, establish procedures, and provide guidance to ensure that our
decisions are based on the best scientific data available. They require
our biologists, to the extent consistent with the Act and with the use
of the best scientific data available, to use primary and original
sources of information as the basis for recommendations to designate
critical habitat.
When we are determining which areas should be designated as
critical habitat, our primary source of information is generally the
information compiled in the SSA report and information developed during
the listing process for the species. Additional information sources may
include any generalized conservation strategy, criteria, or outline
that may have been developed for the species; the recovery plan for the
species; articles in peer-reviewed journals; conservation plans
developed by States and counties; scientific status surveys and
studies; biological assessments; other unpublished materials; or
experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another
over time. We recognize that critical habitat designated at a
particular point in time may not include all of the habitat areas that
we may later determine are necessary for the recovery of the species.
For these reasons, a critical habitat designation does not signal that
habitat outside the designated area is unimportant or may not be needed
for recovery of the species. Areas that are important to the
conservation of the species, both inside and outside the critical
habitat designation, will continue to be subject to: (1) Conservation
actions implemented under section 7(a)(1) of the Act; (2) regulatory
protections afforded by the requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their actions are not likely to
jeopardize the continued existence of any endangered or threatened
species; and (3) the prohibitions found in the 4(d) rule. Federally
funded or permitted projects affecting listed species outside their
designated critical habitat areas may still result in jeopardy findings
in some cases. These protections and conservation tools will continue
to contribute to recovery of the species.
[[Page 92769]]
Similarly, critical habitat designations made on the basis of the best
scientific data available at the time of designation will not control
the direction and substance of future recovery plans, habitat
conservation plans (HCPs), or other species conservation planning
efforts if new information available at the time of those planning
efforts calls for a different outcome.
Physical or Biological Features Essential to the Conservation of the
Species
In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12(b), in determining which areas we will designate as
critical habitat from within the geographical area occupied by the
species at the time of listing, we consider the physical or biological
features that are essential to the conservation of the species and
which may require special management considerations or protection. The
regulations at 50 CFR 424.02 define ``physical or biological features
essential to the conservation of the species'' as the features that
occur in specific areas and that are essential to support the life-
history needs of the species, including, but not limited to, water
characteristics, soil type, geological features, sites, prey,
vegetation, symbiotic species, or other features. A feature may be a
single habitat characteristic or a more complex combination of habitat
characteristics. Features may include habitat characteristics that
support ephemeral or dynamic habitat conditions. Features may also be
expressed in terms relating to principles of conservation biology, such
as patch size, distribution distances, and connectivity. For example,
physical features essential to the conservation of the species might
include gravel of a particular size required for spawning, alkaline
soil for seed germination, protective cover for migration, or
susceptibility to flooding or fire that maintains necessary early-
successional habitat characteristics. Biological features might include
prey species, forage grasses, specific kinds or ages of trees for
roosting or nesting, symbiotic fungi, or absence of a particular level
of nonnative species consistent with conservation needs of the listed
species. The features may also be combinations of habitat
characteristics and may encompass the relationship between
characteristics or the necessary amount of a characteristic essential
to support the life history of the species.
In considering whether features are essential to the conservation
of the species, we may consider an appropriate quality, quantity, and
spatial and temporal arrangement of habitat characteristics in the
context of the life-history needs, condition, and status of the
species. These characteristics include, but are not limited to, space
for individual and population growth and for normal behavior; food,
water, air, light, minerals, or other nutritional or physiological
requirements; cover or shelter; sites for breeding, reproduction, or
rearing (or development) of offspring; and habitats that are protected
from disturbance.
The individual needs of Pecos pupfish vary somewhat by life stage
(egg, hatchling, juvenile, adult); however, as an aquatic species,
Pecos pupfish need adequate water quantity and water quality to meet
their resource functions, which include feeding, growth, survival, and
breeding. The Pecos pupfish occurs in a variety of aquatic environments
including wetlands, sinkholes, impoundments, streams, springs, and
rivers, specifically the Pecos River mainstem (Hoagstrom and Brooks
1999, pp. 14-16; Collyer et al. 2015, p. 182). All life stages of the
Pecos pupfish prefer environments with little to no water flow, and, in
areas with flows, they typically occupy pools and shallow runs and
riffles (Hoagstrom and Brooks 1999, pp. 36, 45). Pecos pupfish tolerate
high salinity (less than 35,000 mg/L) and low dissolved oxygen (greater
than 2.5 mg/L), and while the specific thermal tolerance of Pecos
pupfish is unknown, studies examining thermal tolerance of other
pupfish found tolerance to range from below 0 [deg]C to 45 [deg]C (23
[deg]F to 113 [deg]F) (Bennett and Beitinger 1997, pp. 81-85; Hoagstrom
and Brooks 1999, pp. 21, 31; Propst 1999, pp. 67-68). However, data
collected in studies of desert pupfish found that temperatures above
42.7 [deg]C (108.9 [deg]F) may be lethal (Schoenherr and Feldmeth 1992,
p. 50; BEEC 2010, p. 8). These physical conditions (dissolved oxygen,
salinity, and temperature) can be greatly affected by spring discharge
and other flow parameters (Kodric-Brown 1975, pp. 3, 6). Overwintering
juvenile and adult Pecos pupfish need dense aquatic vegetation and
flocculent materials (such as fine detritus or non-living organic
matter) in the substrate (Kodric-Brown 1977, p. 752; Hoagstrom et al.
2015, p. 17). Therefore, sufficient water quality and water quantity
that provides the appropriate conditions for the Pecos pupfish is
essential to the species.
Spawning adult Pecos pupfish require slow-moving waters that are
less than 2 m (6.56 ft) deep, and in areas with topographic diversity
that include a variety of underwater features such as crevices,
boulders, large rocks, scattered pebbles, and aquatic plants that are
used for oviposition sites (Kodric-Brown 1975, p. 35; 1977, pp. 750-
751, 753-756, and 761-762). Rocky embankments appear to be the most
desirable breeding substrate, and the density of territorial males is
highest in dense patches of aquatic vegetation, and lowest in flat
silty areas with isolated rocks (Kodric-Brown 1975, pp. 20, 34-35).
Female Pecos pupfish lay individual eggs that adhere to spawning
substrate, such as vegetation or rocks (Kodric-Brown 1977, pp. 751,
761-762, 764). Therefore, habitat with crevices, boulders, large rocks,
scattered pebbles, and aquatic plants is essential to the species.
The introduction of the nonnative, invasive sheepshead minnow has
the potential to negatively affect Pecos pupfish through hybridization
(Echelle et al. 2003b, entire; Echelle and Connor 1989, pp. 725-726).
Hybridization eventually leads to the loss of non-introgressed
(genetically pure) Pecos pupfish in the area of introgression (Echelle
and Connor 1989, p. 725; Echelle et al. 2003b, entire). Sheepshead
minnow also outcompete the Pecos pupfish for resources (Echelle et al.
2003b, entire; Echelle and Connor 1989, pp. 725-726). Therefore, the
absence of this nonnative invasive species is essential to the Pecos
pupfish. Bait bucket transfers of sheepshead minnow are most likely in
the Upper Pecos Unit. Bait bucket transfers are highly unlikely to
occur in any of the other AUs as these generally are either well
controlled or do not contain game fish species. As such, the most
likely route for sheepshead minnow introgression would be from the
Upper Pecos River AU to the Salt Creek Wilderness and Middle Tract
Wetlands, which are both hydrologically connected to the upper Pecos
River during flooding events, allowing for potential movement of
sheepshead minnow into these off-channel habitats.
Summary of Essential Physical or Biological Features
We derive the specific physical or biological features essential to
the conservation of Pecos pupfish from studies of the species' habitat,
ecology, and life history as described below. Additional information
can be found in the SSA report (Service 2024, entire; available on
<a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No. FWS-R2-ES-2024-0143). We
have determined that the following physical or biological features are
essential to the conservation of Pecos pupfish:
(1) Water quality parameters that support all life stages of the
Pecos pupfish, including:
[[Page 92770]]
(a) Absence of pollutants, or a level of contaminants low enough
that it does not negatively impact necessary water quality conditions
for Pecos pupfish individuals;
(b) Salinity less than 35,000 mg/L;
(c) Temperature less than 42.7 [deg]C (108.9 [deg]F); and
(d) Dissolved oxygen greater than 2.5 mg/L.
(2) Sufficient water quantity parameters that support all life
stages of the Pecos pupfish, including:
(a) Permanent water in some area of habitat; and
(b) Water depth less than 2 m (6.56 ft) deep to allow for thermal
refugia and breeding.
(3) Presence of silt-free underwater features such as crevices,
boulders, large rocks, scattered pebbles, and aquatic plants that are
used for egg deposition.
(4) Absence of nonnative invasive sheepshead minnow.
Special Management Considerations or Protection
When designating critical habitat, we assess whether the specific
areas within the geographical area occupied by the species at the time
of listing contain features which are essential to the conservation of
the species and which may require special management considerations or
protection. The features essential to the conservation of this species
may require special management considerations or protection to reduce
the following threats: introduction of sheepshead minnow, habitat
degradation due to declines in water quantity and water quality, and
habitat fragmentation.
Management activities that could ameliorate these threats include,
but are not limited to: (1) construction and maintenance of barriers
that prevent the spread of sheepshead minnow; (2) enforcement of
existing State regulatory mechanisms that prohibit bait-bucket releases
of sheepshead minnow in New Mexico and Texas; (3) active management of
wetlands to provide for adequate water quantity and flow; (4) securing
water rights to provide long-term spring flows; (5) monitoring and
preventing water quality impairments from upland sources such as
agricultural runoff and industrial pollutants; and (6) survey and
monitoring to further characterize the extent and spread of
hybridization with sheepshead minnows.
Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act, we use the best
scientific data available to designate critical habitat. In accordance
with the Act and our implementing regulations at 50 CFR 424.12(b), we
review available information pertaining to the habitat requirements of
the species and identify specific areas within the geographical area
occupied by the species at the time of listing and any specific areas
outside the geographical area occupied by the species to be considered
for designation as critical habitat. We are not currently proposing to
designate any areas outside the geographical area occupied by the
species because (1) we have not identified any unoccupied areas that
meet the definition of critical habitat, and (2) we have determined
that the occupied areas are sufficient to conserve the species.
We anticipate that recovery will require conserving the genetic
diversity of extant populations across the species' current range and
maintaining and, where necessary, improving habitat and habitat
connectivity to ensure the long-term viability of the Pecos pupfish.
This proposed critical habitat designation delineates the habitat that
is physically occupied and used by the species rather than delineating
all land or aquatic areas that influence the species. We have
determined that the areas currently occupied by the Pecos pupfish would
maintain the species' resiliency, redundancy, and representation and
are sufficient to conserve the species. Therefore, we are not currently
proposing to designate any areas outside the geographical area occupied
by the species. Sources of data for this proposed critical habitat
include multiple databases maintained by universities and State
agencies, scientific and agency reports, and numerous survey reports
throughout the species' range (Service 2024, pp. 28-34).
In summary, for areas within the geographical area occupied by the
species at the time of listing, we delineated critical habitat unit
boundaries using the following criteria:
(1) We delineated areas within the historical range that had
positive survey data between the year 1992 and the time of listing (see
Service 2024).
(2) We terminated stream segments at barriers, confluences, areas
where genetically pure Pecos pupfish have been extirpated, other
obvious unsuitable habitat, or a location selected based on expert
knowledge of a lack of presence.
(3) We included connecting stream segments between occupied stream
segments as long as the inclusion does not disagree with criterion (2)
and there are no data to suggest that the Pecos pupfish is not present.
When determining proposed critical habitat boundaries, we made
every effort to avoid including developed areas such as lands covered
by buildings, pavement, and other structures because such lands lack
physical or biological features necessary for Pecos pupfish. The scale
of the maps we prepared under the parameters for publication within the
Code of Federal Regulations may not reflect the exclusion of such
developed lands. Any such lands inadvertently left inside critical
habitat boundaries shown on the maps of this proposed rule have been
excluded by text in the proposed rule and are not proposed for
designation as critical habitat. Therefore, if the critical habitat is
finalized as proposed, a Federal action involving these lands would not
trigger section 7 consultation with respect to critical habitat and the
requirement of no adverse modification unless the specific action would
affect the physical or biological features in the adjacent critical
habitat.
The proposed critical habitat designation is defined by the map or
maps, as modified by any accompanying regulatory text, presented at the
end of this document under Proposed Regulation Promulgation.
Proposed Critical Habitat Designation
We are proposing to designate five units of critical habitat for
Pecos pupfish: 136.12 river mi (219.06 river km) of instream habitat
(to the ordinary high water mark, not including riparian areas) and
26,555.54 acres (10,746.64 ha) of lands that encompass numerous
isolated sinkholes and wetland areas. The critical habitat areas we
describe below constitute our current best assessment of areas that
meet the definition of critical habitat for Pecos pupfish.
The five areas we propose as critical habitat are: (1) Upper Pecos
River Unit; (2) Salt Creek Wilderness Unit; (3) Bitter Lake Unit; (4)
BLM Overflow Wetlands/Bottomless Lakes Unit; and (5) Salt Creek (TX)
Unit. Table 5 shows the proposed critical habitat units and the
approximate area of each unit. The Bitter Lake Unit includes both the
Bitter Creek Drainage and Bitter Lake NWR Middle Tract Wetlands AUs
(see table 2 for a list of the AUs). The BLM Overflow Wetlands/
Bottomless Lakes Unit includes both the Bottomless Lakes State Park and
BLM Overflow Wetlands and Lea Lake AUs. Two AUs from the SSA report,
the Middle Pecos River and Lower Pecos River units, are not proposed as
critical habitat units because no extant genetically pure Pecos pupfish
remain in these units.
[[Page 92771]]
Table 5--Proposed Critical Habitat Units for Pecos Pupfish
[Area e
[…truncated; see source link]Indexed from Federal Register on November 22, 2024.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.