92744 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

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. 

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: https://

www.regulations.gov. 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 https:// 

www.regulations.gov. 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 

https://www.fws.gov/office/new-mexicoecological-services, at https://

www.regulations.gov 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 https://

www.regulations.gov at Docket No. 

FWS–R2–ES–2024–0143 and on the 

Service’s website at https://

www.fws.gov/office/new-mexicoecological-services. 

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-ofcontact in the United States. Please see 

Docket No. FWS–R2–ES–2024–0143 on 

https://www.regulations.gov 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 https:// 

www.regulations.gov, 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 https://www.regulations.gov. 

Comments and materials we receive, 

as well as supporting documentation we 

used in preparing this proposed rule, 

will be available for public inspection 

on https://www.regulations.gov. 

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 


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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 multispecies 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 (https:// 

www.fws.gov/sites/default/files/ 

documents/peer-review-policy-directorsmemo-2016-08-22.pdf), 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 https://

www.regulations.gov and https://

www.fws.gov/office/new-mexicoecological-services. 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, deepbodied (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 (KodricBrown 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 (°C) (86 degrees 

Fahrenheit (°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 

https://www.doi.gov/sites/ 

doi.opengov.ibmcloud.com/files/ 

uploads/M-37021.pdf). 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’ lifehistory 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 


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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 https://www.regulations.gov and at 

https://www.fws.gov/office/new-mexicoecological-services. 

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 latecentury. 

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 ......................................................................................... • Warm water temperatures between May and September. 

• Suitable oviposition sites (such as crevices, boulders, pebbles, scattered rocks, and subsurface vegetation mats). 

• Shallow water less than 2 m (6.56 ft) deep. 

Egg ........................................................................................................... • Salinities greater than 35,000 milligrams/liter (mg/L). 

Juvenile/non-breeding adults .................................................................... • Adequate abundance of food (algae, insects, vegetation, etc.). 

Overwintering adults and juveniles .......................................................... • Dense vegetation. 

• Deeper water. 

All .............................................................................................................. • 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 × 

sheepshead minnow hybrid (Connor 

1987, p. 2; Echelle and Connor 1989, pp. 

717–720). In 1997, Pecos pupfish × 

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 nonintrogressed Pecos pupfish are 

extirpated from the Pecos River below 


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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 (KodricBrown 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 (KodricBrown 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 (KodricBrown 1975, pp. 20, 34–35). During the 

colder months when water temperatures 

drop below 10 °C (50 °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. 


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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 baitbucket 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 


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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 °C) 

(2 (°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 offchannel 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. 


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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 wellconnected 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 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 92753 

population resiliency and species’ 

redundancy and representation. 

BILLING CODE 4333–15–P 

BILLING CODE 4333–15–C 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.002</GPH>

Figure 1-Pecos pupfish range map, distributed across the Pecos River Basin. 

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0 City 
92754 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

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 

introgression with 

sheepshead minnow. 

Extant or presumed extant observed at, or in 

the vicinity of, each of 

these sites at least 

once within the last 5 

years. 

Stable and sufficient 

water availability 

throughout the unit. 

Low flow or drying 

events documented, 

but no long-term drying 

events recorded. 

No severe impairments 

to water quality documented and no recorded contamination 

events. 

Unit has a diverse habitat 

assemblage within the 

unit (streams/river, 

wetlands, and sinkholes). 

Moderate condition (moderate resiliency).Introgression possible in 

the unit, but no confirmation. 

Two or fewer of the 

known occupied sites 

confirmed or presumed 

extirpated. 

Occasional low flows or 

drying events across 

<50% of the unit with 

rare long-term drying 

events documented. 

Occasional water quality 

impairments documented, likely linked to 

low flows. No documented exposure to 

surface contaminants. 

Fish restricted to just a 

single habitat type 

within the unit. 

Low condition (low resiliency).Introgression only in a 

portion of the unit. 

Pupfish extant at 50% or 

fewer of sites identified. Populations low 

enough that fish are 

not detected on 50% 

or more visits to occupied locations. 

Routine low flows and 

drying events across 

the majority of the unit 

and regular long-term 

drying events. 

Documented exposure to 

surface contaminants 

within much of the unit. 

N/A. 

Likely extirpated ............... Confirmed introgression 

throughout the unit. 

N/A N/A N/A N/A. 


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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

Risk category Analysis unit condition Estimated chance of extirpation 

for 20 years 

Numerical 

extirpation 

risk estimate 

Threats characterization 

Low risk .......................................... High condition ............................... Extirpation is very unlikely ............ <10% Threats to pupfish needs are minimized or limited in spatial extent 

within the unit. 

Moderate risk .................................. Moderate condition ....................... Extirpation is unlikely .................... 10–40% Threats to pupfish needs are 

widespread throughout the unit 

but limited in duration or severity. 

High risk .......................................... Low condition ................................ Extirpation risk ranges from being 

about as likely as not to being 

very likely.

>40% Threats to pupfish are severe and 

pervasive throughout the 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, 


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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. 


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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 


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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 


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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: 

• Scenario 1: Hot and dry (RCP 8.5)— 

Steep increase in annual average 

temperature coupled with steep 

decreases in annual precipitation. 

• Scenario 2: Hot and wet (RCP 8.5)— 

Steep increase in annual average 

temperature coupled with an increase in 

annual average precipitation. 

• 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. 


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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 °F (¥10.4 °C) to an 

average surface temperature in excess of 

70 °F (21.1 °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 


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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 


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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 nonintrogressed 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 


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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 yearround 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 


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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 


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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, selfsustaining, 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 (https:// 

www.fws.gov/program/endangeredspecies), 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: https://www.fws.gov/ 

service/financial-assistance. 

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 


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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; https://

ipac.ecosphere.fws.gov/), 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 § 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 


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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 otherwiseprohibited 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 livecapturing 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 captivebred 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 


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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. 


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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 lifehistory 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 earlysuccessional 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 lifehistory 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 °C to 45 °C (23 °F to 113 °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 °C 

(108.9 °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 (KodricBrown 1975, pp. 3, 6). Overwintering 

juvenile and adult Pecos pupfish need 

dense aquatic vegetation and flocculent 

materials (such as fine detritus or nonliving 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 (KodricBrown 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 nonintrogressed (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 offchannel 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 https://

www.regulations.gov 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: 


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(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 °C 

(108.9 °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 longterm 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 longterm 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. 


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TABLE 5—PROPOSED CRITICAL HABITAT UNITS FOR PECOS PUPFISH

[Area estimates reflect all land within critical habitat unit boundaries.] 

Critical habitat unit Occupied? 

Land 

ownership 

by type 

Length of unit in river miles (km) or unit size in acres 

(ha) 

1. Upper Pecos River ....................................................... Yes .............

Yes .............

Yes .............

Federal .......

State ..........

Private ........

32.61 river mi (52.48 km). 

4.86 river mi (7.82 km). 

84.41 river mi (135.84 km). 

2. Salt Creek Wilderness .................................................. Yes .............

Yes .............

Federal ....... 5,428.74 acres (2,196.93 ha). 

3. Bitter Lake .................................................................... Yes .............

Yes .............

Yes .............

Federal .......

State ..........

Private ........

9,663.15 acres (3,910.54 ha). 

87.87 acres (35.56 ha). 

2,221.88 acres (899.16 ha). 

4. BLM Overflow Wetlands/Bottomless Lakes ................. Yes .............

Yes .............

Yes .............

Federal .......

State ..........

Private ........

1,784 acres (721.96 ha). 

1,854.78 acres (750.60 ha). 

5,515.12 acres (2,231.89 ha). 

5. Salt Creek (TX) ............................................................ Yes ............. Private ........ 14.24 river mi (22.92 km) 

Total ........................................................................... .................... .................... 136.12 river mi (219.06 km). 

26,555.54 acres (10,746.64 ha). 

Note: Area sizes may not sum due to rounding. 

We present brief descriptions of all 

units, and reasons why they meet the 

definition of critical habitat for Pecos 

pupfish, below. 

Unit 1: Upper Pecos River 

The Upper Pecos River Unit consists 

of 121.88 river mi (196.15 km). The 

Upper Pecos River Unit begins at 

Bosque Draw in Chaves County, New 

Mexico, and extends south on the Pecos 

River to (but not including) Brantley 

Lake, in Eddy County, New Mexico. The 

entire unit is currently occupied by the 

species and supports all of the physical 

and biological features (PBFs) essential 

to the conservation of the species. 

Ownership of the adjacent riparian areas 

is 26.76 percent Federal, 3.99 percent 

State, and 69.26 percent private. 

Based on prior introductions, without 

barriers, sheepshead minnow could 

spread through all the accessible 

portions of the Upper Pecos River Unit. 

In addition, this unit is subject to 

regular severe low and intermittent 

flows. Conservation measures are in 

place by the BOR under a biological 

opinion to minimize river intermittency 

for the federally threatened Pecos 

bluntnose shiner. These measures buffer 

the threat of river drying for Pecos 

bluntnose shiner and, by extension, 

Pecos pupfish. 

The entirety of this unit has ongoing 

water quality concerns and is 

considered impaired. Water availability 

in the unit is primarily influenced by 

the management of the upstream dam at 

Fort Sumner. River flows downstream of 

Bitter Lake NWR are influenced by 

groundwater pumping by PVACD water 

users and return flows from crop 

irrigation. Therefore, special 

management considerations may be 

required to maintain barriers that 

prevent the spread of sheepshead 

minnow into the upper Pecos River, 

enforce prohibitions of bait-bucket 

releases of sheepshead minnow in New 

Mexico and Texas, maintain adequate 

water quantity and flow, monitor and 

prevent water quality impairments from 

upland sources such as agricultural 

runoff and industrial pollutants, 

routinely monitor for Pecos pupfish and 

to document the extent and spread of 

hybridization with sheepshead 

minnows. The Upper Pecos River Unit 

is occupied by two federally listed 

species, the threatened Pecos sunflower 

(Helianthus paradoxus) and the 

endangered Pecos bluntnose shiner. 

There is a complete overlap with 

designated critical habitat for the Pecos 

bluntnose shiner (see 50 CFR 17.95(e); 

52 FR 5295, February 20, 1987). 

Unit 2: Salt Creek Wilderness 

The Salt Creek Wilderness Unit 

contains Salt Creek (New Mexico (NM)) 

and four sinkholes within 5,428.74 acres 

(2,196.93 ha) of land between 

Cottonwood Road and the confluence 

with the Pecos River in Chaves County, 

New Mexico. Areas within this 

proposed critical habitat unit are limited 

to the sinkholes and wetlands areas, and 

do not include the lands adjacent to the 

wetted areas. The wetted areas within 

this unit are currently occupied by the 

species and support all of the PBFs 

essential to the conservation of the 

species. Ownership of the adjacent 

riparian areas is 100 percent Federal, 

primarily encompassing the Refuge 

North Tract of Bitter Lake NWR. Salt 

Creek (NM) is an ephemeral stream with 

permanent water in deeper pools along 

the stream course. There is a low risk of 

introgression with sheepshead minnow 

into the sinkholes within the Salt Creek 

Wilderness Unit, as they are isolated 

from the Pecos River. Although fish 

remain extant at several locations in the 

unit, the extent of habitat is small, and 

Salt Creek (NM) is subject to mortality 

events. Therefore, special management 

considerations may be required to 

enforce prohibitions of bait-bucket 

releases of sheepshead minnow in New 

Mexico and Texas, maintain fish 

barriers to prevent spread of sheepshead 

minnow, maintain adequate water 

quantity and flow in Salt Creek (NM), 

monitor and prevent water quality 

impairments from upland sources such 

as agricultural runoff and industrial 

pollutants, and routinely monitor for 

Pecos pupfish to document the spread 

and extent of hybridization with 

sheepshead minnows. There is no 

overlap with any designated critical 

habitat for other listed species. 

Unit 3: Bitter Lake 

The Bitter Lake Unit contains Bitter 

Creek and numerous isolated sinkholes, 

spring ditches, managed and natural 

wetlands, and oxbows of the Pecos 

River within 11,972.90 acres (4,845.26 

ha) of land between Bitter Lake Road in 

the north and Miami Road in the South 

in Chaves County, New Mexico. All of 

the wetted areas in the entire unit are 

currently occupied by the species and 

support all of the PBFs essential to the 

conservation of the species. Ownership 

of the adjacent riparian areas is 80.71 

percent Federal, 0.73 percent State, and 

18.56 percent private. Most of the unit 

falls within Bitter Lake NWR. While the 

sinkholes in the Bitter Lake Unit are 

isolated and well protected from 

sheepshead minnow introgression, there 


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is a potential to introduce sheepshead 

minnow to the managed wetlands 

within Bitter Lake NWR if the fish 

barriers are overtopped in high flow 

events. Water quality surveys have not 

detected any impairment to the aquatic 

environments in the unit. Furthermore, 

most of the unit is within Bitter Lake 

NWR, which protects the unit from 

direct surface contamination. 

The water in Bitter Creek is 

supplemented by precipitation during 

wet seasons or years, and during 

drought years, when precipitation is not 

sufficient to maintain surface flows, 

portions of Bitter Creek dry out. 

Therefore, special management 

considerations may be required to 

maintain adequate flows in Bitter Creek 

to maintain habitat connectivity and for 

routine monitoring for Pecos pupfish. 

The Bitter Lake Unit is occupied by 

seven federally listed species, the 

threatened Wright’s marsh thistle 

(Cirsium wrightii), threatened Pecos 

sunflower, endangered Noel’s amphipod 

(Gammarus desperatus), endangered 

Roswell springsnail (Pyrgulopsis 

roswellensis), endangered Pecos 

assiminea (Assiminea pecos), 

endangered Pecos gambusia (Gambusia 

nobilis), and the endangered Koster’s 

springsnail (Juturnia kosteri). There is a 

complete overlap with designated 

critical habitat for the Wright’s marsh 

thistle (see 50 CFR 17.96(a); 88 FR 

25208, May 25, 2023), Noel’s amphipod 

(see 50 CFR 17.95(h); 76 FR 33036, June 

7, 2011), Roswell springsnail (see 50 

CFR 17.95(f); 77 FR 33036, June 7, 

2011), Pecos assiminea (see 50 CFR 

17.95(f); 76 FR 33036, June 7, 2011), and 

Koster’s springsnail (see 50 CFR 

17.95(f); 76 FR 33036, June 7, 2011). 

Unit 4: BLM Overflow Wetlands/ 

Bottomless Lakes 

The BLM Overflow Wetlands/ 

Bottomless Lakes Unit contains a 

wetland and several sinkholes within 

9,153.90 acres (3,704.45 ha) of land in 

Chaves County, New Mexico. This unit 

is east of the Pecos River and between 

Highway 380 in the north and the 

approximate southern border of the 

BLM Overflow Wetlands ACEC in the 

South. The wetlands and sinkholes 

within this unit are currently occupied 

by the species and support all of the 

PBFs essential to the conservation of the 

species. Ownership of the adjacent 

riparian areas is 19.49 percent Federal, 

20.26 percent State, and 60.25 percent 

private. The majority of occupied 

habitat within this unit falls within 

Bottomless Lakes State Park and the 

BLM Overflow Wetlands ACEC. 

Although the BLM Overflow 

Wetlands contain constructed and 

maintained fish barriers, a severe flood 

could overtop or wash out these 

barriers, presenting a risk from 

sheepshead minnow, which are present 

near this population. The isolated 

sinkholes and wetlands within 

Bottomless Lakes State Park are well 

protected from sheepshead minnow 

introgression because (1) they do not 

contain game fish species and (2) fishing 

with baitfish is illegal, making these 

areas a low risk of bait-bucket releases. 

In 2020, a complete loss of pupfish in 

Upper Figure 8 Lake sinkhole is 

speculated to have been caused by a 

golden algae outbreak, but the actual 

causes are unknown. Therefore, special 

management considerations may be 

required for routine monitoring for 

Pecos pupfish to document the extent 

and spread of hybridization with 

sheepshead minnows. The BLM 

Overflow Wetlands/Bottomless Lakes 

Unit is occupied by one federally listed 

species, the threatened Pecos sunflower. 

Unit 5: Salt Creek (TX) 

The Salt Creek (TX) Unit consists of 

14.24 river mi (22.92 km) in Culberson 

and Reeves Counties, Texas. The unit 

begins at RM 2119 in Culberson County, 

Texas, and extends northeast on Salt 

Creek to RM 652 in Reeves County, 

Texas. Ownership of the adjacent 

riparian areas is entirely under private 

ownership. 

Pecos pupfish from the lower reach of 

the Salt Creek (TX) Unit, near the 

confluence with the Pecos River, were 

confirmed introgressed with sheepshead 

minnow, though an unidentified 

physical barrier appears to have limited 

the spread of introgressed fish further 

upstream. The entirety of this unit has 

ongoing water quality concerns and is 

considered impaired due to 

contaminants introduced from upland 

sources such as agricultural runoff and 

industrial pollutants from oil and gas 

extraction. While during wet seasons or 

years, the water in Salt Creek (TX) is 

supplemented by precipitation, during 

drought years, the precipitation is not 

sufficient to maintain surface flows. 

Therefore, special management 

considerations may be required to 

maintain barriers that prevent the 

spread of sheepshead minnow into the 

upper portion of Salt Creek (TX), 

enforce prohibitions of bait-bucket 

releases of sheepshead minnow in New 

Mexico and Texas, maintain adequate 

water quantity and flow, and monitor 

and prevent water quality impairments 

from upland sources such as 

agricultural runoff and industrial 

pollutants, and to survey and monitor 

the extent and spread of hybridization 

with sheepshead minnows. There is no 

overlap with any designated critical 

habitat for other listed species in the 

Salt Creek (TX) Unit. 

Effects of Critical Habitat Designation 

Section 7 Consultation 

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, 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 

proposed critical habitat. 

Destruction or adverse modification 

means a direct or indirect alteration that 

appreciably diminishes the value of 

critical habitat as a whole for the 

conservation of a listed species (50 CFR 

402.02). 

Compliance with the requirements of 

section 7(a)(2) is documented through 

our issuance of: 

(1) A concurrence letter for Federal 

actions that may affect, but are not 

likely to adversely affect, listed species 

or critical habitat; or 

(2) A biological opinion for Federal 

actions that may affect, and are likely to 

adversely affect, listed species or critical 

habitat. 

When we issue a biological opinion 

concluding that a project is likely to 

jeopardize the continued existence of a 

listed species and/or destroy or 

adversely modify critical habitat, we 

provide reasonable and prudent 

alternatives to the project, if any are 

identifiable, that would avoid the 

likelihood of jeopardy and/or 

destruction or adverse modification of 

critical habitat. We define ‘‘reasonable 

and prudent alternatives’’ (at 50 CFR 

402.02) as alternative actions identified 

during formal consultation that: 

(1) Can be implemented in a manner 

consistent with the intended purpose of 

the action, 

(2) Can be implemented consistent 

with the scope of the Federal agency’s 

legal authority and jurisdiction, 

(3) Are economically and 

technologically feasible, and 

(4) Would, in the Service Director’s 

opinion, avoid the likelihood of 

jeopardizing the continued existence of 

the listed species or avoid the likelihood 

of destroying or adversely modifying 

critical habitat. 


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Reasonable and prudent alternatives 

can vary from slight project 

modifications to extensive redesign or 

relocation of the project. Costs 

associated with implementing a 

reasonable and prudent alternative are 

similarly variable. 

Regulations at 50 CFR 402.16 set forth 

requirements for Federal agencies to 

reinitiate consultation. Reinitiation of 

consultation is required and shall be 

requested by the Federal agency, where 

discretionary Federal involvement or 

control over the action has been 

retained or is authorized by law and: (1) 

If the amount or extent of taking 

specified in the incidental take 

statement is exceeded; (2) if new 

information reveals effects of the action 

that may affect listed species or critical 

habitat in a manner or to an extent not 

previously considered; (3) if the 

identified action is subsequently 

modified in a manner that causes an 

effect to the listed species or critical 

habitat that was not considered in the 

biological opinion or written 

concurrence; or (4) if a new species is 

listed or critical habitat designated that 

may be affected by the identified action. 

As provided in 50 CFR 402.16, the 

requirement to reinitiate consultations 

for new species listings or critical 

habitat designation does not apply to 

certain agency actions (e.g., land 

management plans issued by the Bureau 

of Land Management in certain 

circumstances). 

Destruction or Adverse Modification of 

Critical Habitat 

The key factor related to the 

destruction or adverse modification 

determination is whether 

implementation of the proposed Federal 

action directly or indirectly alters the 

designated critical habitat in a way that 

appreciably diminishes the value of the 

critical habitat for the conservation of 

the listed species. As discussed above, 

the role of critical habitat is to support 

physical or biological features essential 

to the conservation of a listed species 

and provide for the conservation of the 

species. 

Section 4(b)(8) of the Act requires that 

our Federal Register documents ‘‘shall, 

to the maximum extent practicable also 

include a brief description and 

evaluation of those activities (whether 

public or private) which, in the opinion 

of the Secretary, if undertaken may 

adversely modify [critical] habitat, or 

may be affected by such designation.’’ 

Activities that may be affected by 

designation of critical habitat for the 

Pecos pupfish include those that may 

affect the physical or biological features 

of the proposed critical habitat (see 

Physical or Biological Features Essential 

to the Conservation of the Species). 

Exemptions 

Application of Section 4(a)(3) of the Act 

Section 4(a)(3)(B)(i) of the Act 

provides that the Secretary shall not 

designate as critical habitat any lands or 

other geographical areas owned or 

controlled by the Department of Defense 

(DoD), or designated for its use, that are 

subject to an integrated natural 

resources management plan (INRMP) 

prepared under section 101 of the Sikes 

Act Improvement Act of 1997 (16 U.S.C. 

670a), if the Secretary determines in 

writing that such plan provides a benefit 

to the species for which critical habitat 

is proposed for designation. No DoD 

lands with a completed INRMP are 

within the proposed critical habitat 

designation. 

Consideration of Impacts Under Section 

4(b)(2) of the Act 

Section 4(b)(2) of the Act states that 

the Secretary shall designate and make 

revisions to critical habitat on the basis 

of the best available scientific data after 

taking into consideration the economic 

impact, national security impact, and 

any other relevant impact of specifying 

any particular area as critical habitat. 

The Secretary may exclude an area from 

critical habitat if the benefits of 

exclusion outweigh those of inclusion, 

so long as exclusion will not result in 

the extinction of the species concerned. 

Exclusion decisions are governed by the 

regulations at 50 CFR 424.19 and the 

‘‘Policy Regarding Implementation of 

Section 4(b)(2) of the Endangered 

Species Act’’ (hereafter, the ‘‘2016 

Policy’’; 81 FR 7226, February 11, 2016), 

both of which were developed jointly 

with the National Marine Fisheries 

Service (NMFS). We also refer to a 2008 

Department of the Interior Solicitor’s 

opinion entitled ‘‘The Secretary’s 

Authority to Exclude Areas from a 

Critical Habitat Designation under 

Section 4(b)(2) of the Endangered 

Species Act’’ (M–37016). 

In considering whether to exclude a 

particular area from the designation, we 

identify the benefits of including the 

area in the designation, identify the 

benefits of excluding the area from the 

designation, and evaluate whether the 

benefits of exclusion outweigh the 

benefits of inclusion. If the analysis 

indicates that the benefits of exclusion 

outweigh the benefits of inclusion, the 

Secretary may exercise discretion to 

exclude the area only if such exclusion 

would not result in the extinction of the 

species. In making the determination to 

exclude a particular area, the statute on 

its face, as well as the legislative history, 

are clear that the Secretary has broad 

discretion regarding which factor(s) to 

use and how much weight to give to any 

factor. In our final rules, we explain any 

decision to exclude areas, as well as 

decisions not to exclude, to make clear 

the rational basis for our decision. We 

describe below the process that we use 

for taking into consideration each 

category of impacts and any initial 

analyses of the relevant impacts. 

Consideration of Economic Impacts 

Section 4(b)(2) of the Act and its 

implementing regulations require that 

we consider the economic impact that 

may result from a designation of critical 

habitat. To assess the probable 

economic impacts of a designation, we 

must first evaluate specific land uses or 

activities and projects that may occur in 

the area of the critical habitat. We then 

must evaluate the impacts that a specific 

critical habitat designation may have on 

restricting or modifying specific land 

uses or activities for the benefit of the 

species and its habitat within the areas 

proposed. We then identify which 

conservation efforts may be the result of 

the species being listed under the Act 

versus those attributed solely to the 

designation of critical habitat for this 

particular species. The probable 

economic impact of a proposed critical 

habitat designation is analyzed by 

comparing scenarios both ‘‘with critical 

habitat’’ and ‘‘without critical habitat.’’ 

The ‘‘without critical habitat’’ 

scenario represents the baseline for the 

analysis, which includes the existing 

regulatory and socio-economic burden 

imposed on landowners, managers, or 

other resource users potentially affected 

by the designation of critical habitat 

(e.g., under the Federal listing as well as 

other Federal, State, and local 

regulations). Therefore, the baseline 

represents the costs of all efforts 

attributable to the listing of the species 

under the Act (i.e., conservation of the 

species and its habitat incurred 

regardless of whether critical habitat is 

designated). The ‘‘with critical habitat’’ 

scenario describes the incremental 

impacts associated specifically with the 

designation of critical habitat for the 

species. The incremental conservation 

efforts and associated impacts would 

not be expected without the designation 

of critical habitat for the species. In 

other words, the incremental costs are 

those attributable solely to the 

designation of critical habitat, above and 

beyond the baseline costs. These are the 

costs we use when evaluating the 

benefits of inclusion and exclusion of 

particular areas from the final 

designation of critical habitat should we 


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choose to conduct a discretionary 

section 4(b)(2) exclusion analysis. 

Executive Order (E.O.) 14094 amends 

and reaffirms E.O. 12866 and E.O. 13563 

and directs Federal agencies to assess 

the costs and benefits of available 

regulatory alternatives in quantitative 

(to the extent feasible) and qualitative 

terms. Consistent with the E.O. 

regulatory analysis requirements, our 

effects analysis under the Act may take 

into consideration impacts to both 

directly and indirectly affected entities, 

where practicable and reasonable. If 

sufficient data are available, we assess 

to the extent practicable the probable 

impacts to both directly and indirectly 

affected entities. Section 3(f) of E.O. 

12866 identifies four criteria when a 

regulation is considered a ‘‘significant 

regulatory action’’ and requires 

additional analysis, review, and 

approval if met. The criterion relevant 

here is whether the designation of 

critical habitat may have an economic 

effect of $200 million or more in any 

given year (section 3(f)(1) of E.O 12866 

as amended by E.O. 14094). Therefore, 

our consideration of economic impacts 

uses a screening analysis to assess 

whether a designation of critical habitat 

for Pecos pupfish is likely to exceed the 

threshold for a regulatory action 

significant under section 3(f)(1) of E.O. 

12866, as amended by E.O. 14094. 

For this particular designation, we 

developed an incremental effects 

memorandum (IEM) considering the 

probable incremental economic impacts 

that may result from this proposed 

designation of critical habitat. The 

information contained in our IEM was 

then used to develop a screening 

analysis of the probable effects of the 

designation of critical habitat for the 

Pecos pupfish (Industrial Economics, 

Inc. (IEc) 2024; entire). We began by 

conducting a screening analysis of the 

proposed designation of critical habitat 

in order to focus our analysis on the key 

factors that are likely to result in 

incremental economic impacts. The 

purpose of the screening analysis is to 

filter out particular geographical areas of 

critical habitat that are already subject 

to such protections and are, therefore, 

unlikely to incur incremental economic 

impacts. In particular, the screening 

analysis considers baseline costs (i.e., 

absent critical habitat designation) and 

includes any probable incremental 

economic impacts where land and water 

use may already be subject to 

conservation plans, land management 

plans, best management practices, or 

regulations that protect the habitat area 

as a result of the Federal listing status 

of the species. Ultimately, the screening 

analysis allows us to focus our analysis 

on evaluating the specific areas or 

sectors that may incur probable 

incremental economic impacts as a 

result of the designation. The presence 

of the listed species in occupied areas 

of critical habitat means that any 

destruction or adverse modification of 

those areas is also likely to jeopardize 

the continued existence of the species. 

Therefore, designating occupied areas as 

critical habitat typically causes little if 

any incremental impacts above and 

beyond the impacts of listing the 

species. As a result, we generally focus 

the screening analysis on areas of 

unoccupied critical habitat (unoccupied 

units or unoccupied areas within 

occupied units). Overall, the screening 

analysis assesses whether designation of 

critical habitat is likely to result in any 

additional management or conservation 

efforts that may incur incremental 

economic impacts. This screening 

analysis combined with the information 

contained in our IEM constitute what 

we consider to be our economic analysis 

of the proposed critical habitat 

designation for the Pecos pupfish and is 

summarized in the narrative below. 

As part of our screening analysis, we 

considered the types of economic 

activities that are likely to occur within 

the areas likely affected by the critical 

habitat designation. In our evaluation of 

the probable incremental economic 

impacts that may result from the 

proposed designation of critical habitat 

for the Pecos pupfish, first we 

identified, in the IEM dated March 26, 

2024, probable incremental economic 

impacts associated with the following 

categories of activities: (1) Federal lands 

management (BLM, Natural Resources 

Conservation Service, BOR, and our 

NWR System), (2) prescribed fire 

projects, (3) pipeline and utility 

crossings, (4) watershed restoration 

activities, (5) road maintenance and 

bridge replacement maintenance, (6) 

pesticide use, (7) construction of 

recreation improvements and 

management of recreation activities, (8) 

stocking practices, (9) surveys and 

monitoring, (10) agriculture, and (11) oil 

and gas exploration and extraction. We 

considered each industry or category 

individually. Additionally, we 

considered whether their activities have 

any Federal involvement. Critical 

habitat designation generally will not 

affect activities that do not have any 

Federal involvement; under the Act, 

designation of critical habitat only 

affects activities conducted, funded, 

permitted, or authorized by Federal 

agencies. If we list the species, in areas 

where the Pecos pupfish is present, 

Federal agencies would be required to 

consult with the Service under section 

7 of the Act on activities they authorize, 

fund, or carry out that may affect the 

species. If when we list the species, we 

also finalize this proposed critical 

habitat designation, Federal agencies 

would be required to consider the 

effects of their actions on the designated 

habitat, and if the Federal action may 

affect critical habitat, our consultations 

would include an evaluation of 

measures to avoid the destruction or 

adverse modification of critical habitat. 

In our IEM, we attempted to clarify 

the distinction between the effects that 

would result from the species being 

listed and those attributable to the 

critical habitat designation (i.e., 

difference between the jeopardy and 

adverse modification standards) for the 

Pecos pupfish’s critical habitat. Because 

the designation of critical habitat for 

Pecos pupfish is being proposed 

concurrently with the listing, it has been 

our experience that it is more difficult 

to discern which conservation efforts 

are attributable to the species being 

listed and those which will result solely 

from the designation of critical habitat. 

However, the following specific 

circumstances in this case help to 

inform our evaluation: (1) The essential 

physical or biological features identified 

for critical habitat are the same features 

essential for the life requisites of the 

species, and (2) any actions that would 

likely adversely affect the essential 

physical or biological features of 

occupied critical habitat are also likely 

to adversely affect the Pecos pupfish 

itself. The IEM outlines our rationale 

concerning this limited distinction 

between baseline conservation efforts 

and incremental impacts of the 

designation of critical habitat for this 

species. This evaluation of the 

incremental effects has been used as the 

basis to evaluate the probable 

incremental economic impacts of this 

proposed designation of critical habitat. 

The proposed critical habitat 

designation for the Pecos pupfish 

includes a total of five units, all of 

which are occupied by the species. 

Ownership of the riparian lands 

adjacent to the two proposed riverine 

units includes 32.61 river mi (52.48 km; 

23.95 percent) Federal, 4.86 river mi 

(7.82 km; 3.57 percent) State, and 98.65 

river mi (158.76 km; 72.47 percent) 

private. Ownership of lands that 

encompass numerous isolated sinkholes 

and wetland areas that are currently 

occupied by the species in three 

proposed units includes 16,875.89 acres 

(6,829.43 ha, 63.55 percent) Federal, 

1,942.65 acres (786.16 ha, 7.32 percent) 

State, and 7,737 acres (3131.05 ha, 29.14 

percent) private. In these areas, any 


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actions that may affect the Pecos 

pupfish or its habitats would also affect 

designated critical habitat. Three of the 

five proposed units overlap with 

existing critical habitat for seven other 

federally listed species, including Pecos 

bluntnose shiner, Koster’s springsnail, 

Pecos sunflower, Noel’s amphipod, 

Wright’s marsh thistle, Roswell 

springsnail, and Pecos assiminea. 

The proposed critical habitat 

designation for the Pecos pupfish totals 

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 

that are currently occupied by the 

species (the sinkholes and wetlands 

areas, not including the lands adjacent 

to the wetted areas). In these areas any 

actions that may affect the species or its 

habitat would also affect designated 

critical habitat, and it is unlikely that 

any additional conservation efforts 

would be recommended to address the 

adverse modification standard over and 

above those recommended to avoid 

jeopardizing the continued existence of 

the Pecos pupfish. Therefore, only 

administrative costs are expected in 100 

percent of the proposed critical habitat 

designation. While this additional 

analysis will require time and resources 

by both the Federal action agency and 

the Service, it is believed that, in most 

circumstances, these costs would 

predominantly be administrative in 

nature and would not be significant. 

The entities most likely to incur 

incremental costs are parties to section 

7 consultations, including Federal 

action agencies and, in some cases, third 

parties, most frequently State agencies 

or municipalities. Activities that we 

expect would be subject to consultations 

that may involve private entities as third 

parties are oil and gas operations that 

may occur on private lands. However, 

based on coordination with State 

agencies, the cost to private entities is 

expected to be relatively minor 

(administrative costs of less than $5,700 

per consultation effort); therefore, they 

would not be significant. 

The probable incremental economic 

impacts of the Pecos pupfish critical 

habitat designation are expected to be 

limited to additional administrative 

effort as well as minor costs of 

conservation efforts resulting from a 

small number of future section 7 

consultations. This limitation is due to 

two factors: (1) the proposed units are 

considered occupied by the Pecos 

pupfish, and occupied units are 

afforded significant baseline protection 

under the Act due to the presence of the 

listed species; and (2) the Pecos pupfish 

receives additional baseline protection 

from co-occurring listed species, which 

include species with overlapping 

critical habitat and similar resource and 

habitat needs. At approximately $5,700 

or less per consultation, the burden 

resulting from designation of critical 

habitat for the Pecos pupfish, based on 

the anticipated annual number of 

consultations and associated 

consultation costs, is not expected to 

exceed $11,000 in most years. The 

designation is unlikely to trigger 

additional requirements under State or 

local regulations. Thus, the annual 

administrative burden is relatively low. 

Any future probable incremental 

economic impacts are not likely to 

exceed $200 million in any single year, 

and impacts that are concentrated in 

any geographical area are not likely as 

a result of this critical habitat 

designation. 

We are soliciting data and comments 

from the public on the economic 

analysis discussed above. During the 

development of a final designation, we 

will consider the information presented 

in the economic analysis and any 

additional information on economic 

impacts we receive during the public 

comment period to determine whether 

any specific areas should be excluded 

from the final critical habitat 

designation under authority of section 

4(b)(2), our implementing regulations at 

50 CFR 424.19, and the 2016 Policy. We 

may exclude an area from critical 

habitat if we determine that the benefits 

of excluding the area outweigh the 

benefits of including the area, provided 

the exclusion will not result in the 

extinction of this species. 

Consideration of National Security 

Impacts 

Section 4(a)(3)(B)(i) of the Act may 

not cover all DoD lands or areas that 

pose potential national-security 

concerns (e.g., a DoD installation that is 

in the process of revising its INRMP for 

a newly listed species or a species 

previously not covered). If a particular 

area is not covered under section 

4(a)(3)(B)(i), then national-security or 

homeland-security concerns are not a 

factor in the process of determining 

what areas meet the definition of 

‘‘critical habitat.’’ However, we must 

still consider impacts on national 

security, including homeland security, 

on those lands or areas not covered by 

section 4(a)(3)(B)(i) because section 

4(b)(2) requires us to consider those 

impacts whenever it designates critical 

habitat. Accordingly, if DoD, 

Department of Homeland Security 

(DHS), or another Federal agency has 

requested exclusion based on an 

assertion of national-security or 

homeland-security concerns, or we have 

otherwise identified national-security or 

homeland-security impacts from 

designating particular areas as critical 

habitat, we generally have reason to 

consider excluding those areas. 

However, we cannot automatically 

exclude requested areas. When DoD, 

DHS, or another Federal agency requests 

exclusion from critical habitat on the 

basis of national-security or homelandsecurity impacts, we must conduct an 

exclusion analysis if the Federal 

requester provides information, 

including a reasonably specific 

justification of an incremental impact 

on national security that would result 

from the designation of that specific 

area as critical habitat. That justification 

could include demonstration of 

probable impacts, such as impacts to 

ongoing border-security patrols and 

surveillance activities, or a delay in 

training or facility construction, as a 

result of compliance with section 7(a)(2) 

of the Act. If the agency requesting the 

exclusion does not provide us with a 

reasonably specific justification, we will 

contact the agency to recommend that it 

provide a specific justification or 

clarification of its concerns relative to 

the probable incremental impact that 

could result from the designation. If we 

conduct an exclusion analysis because 

the agency provides a reasonably 

specific justification or because we 

decide to exercise the discretion to 

conduct an exclusion analysis, we will 

defer to the expert judgment of DoD, 

DHS, or another Federal agency as to: 

(1) Whether activities on its lands or 

waters, or its activities on other lands or 

waters, have national-security or 

homeland-security implications; (2) the 

importance of those implications; and 

(3) the degree to which the cited 

implications would be adversely 

affected in the absence of an exclusion. 

In that circumstance, in conducting a 

discretionary section 4(b)(2) exclusion 

analysis, we will give great weight to 

national-security and homeland-security 

concerns in analyzing the benefits of 

exclusion. 

In preparing this proposal, we have 

determined that the lands within the 

proposed designation of critical habitat 

for Pecos pupfish are not owned or 

managed by the DoD or DHS, and, 

therefore, we anticipate no impact on 

national security or homeland security. 

Consideration of Other Relevant 

Impacts 

Under section 4(b)(2) of the Act, we 

consider any other relevant impacts, in 

addition to economic impacts and 


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impacts on national security discussed 

above. To identify other relevant 

impacts that may affect the exclusion 

analysis, we consider a number of 

factors, including whether there are 

approved and permitted conservation 

agreements or plans covering the 

species in the area—such as safe harbor 

agreements (SHAs), candidate 

conservation agreements with 

assurances (CCAAs) or ‘‘conservation 

benefit agreements’’ or ‘‘conservation 

agreements’’ (‘‘CBAs’’) (CBAs are a new 

type of agreement replacing SHAs and 

CCAAs in use after April 2024 (89 FR 

26070; April 12, 2024)), or HCPs—or 

whether there are non-permitted 

conservation agreements and 

partnerships that may be impaired by 

designation of, or exclusion from, 

critical habitat. In addition, we look at 

whether Tribal conservation plans or 

partnerships, Tribal resources, or 

government-to-government 

relationships of the United States with 

Tribal entities may be affected by the 

designation. We also consider any State, 

local, social, or other impacts that might 

occur because of the designation. 

Summary of Exclusions Considered 

Under 4(b)(2) of the Act 

At this time, we are not considering 

any exclusions from the proposed 

designation based on economic impacts, 

national security impacts, or other 

relevant impacts—such as partnerships, 

management, or protection afforded by 

cooperative management efforts—under 

section 4(b)(2) of the Act. Some areas 

within the proposed designation are 

included in the Conservation Agreement 

for the Pecos Pupfish between and 

among TPWD; NMDGF; New Mexico 

Energy, Minerals and Natural Resources 

Department; New Mexico Department of 

Agriculture; New Mexico Interstate 

Stream Commission; New Mexico State 

Land Office; BLM; and the Service. 

If through the public comment period 

we receive information that we 

determine indicates that there are 

economic, national security, or other 

relevant impacts from designating 

particular areas as critical habitat, then 

as part of developing the final 

designation of critical habitat, we will 

evaluate that information and may 

conduct a discretionary exclusion 

analysis to determine whether to 

exclude those areas under authority of 

section 4(b)(2) and our implementing 

regulations at 50 CFR 424.19. If we 

receive a request for exclusion of a 

particular area and after evaluation of 

supporting information we do not 

exclude, we will fully explain our 

decision in the final rule for this action. 

(Please see ADDRESSES, above, for 

instructions on how to submit 

comments). 

Required Determinations 

Clarity of the Proposed Rule 

We are required by E.O.s 12866 and 

12988 and by the Presidential 

Memorandum of June 1, 1998, to write 

all rules in plain language. This means 

that each rule we publish must: 

(1) Be logically organized; 

(2) Use the active voice to address 

readers directly; 

(3) Use clear language rather than 

jargon; 

(4) Be divided into short sections and 

sentences; and 

(5) Use lists and tables wherever 

possible. 

If you feel that we have not met these 

requirements, send us comments by one 

of the methods listed in ADDRESSES. To 

better help us revise the rulemaking, 

your comments should be as specific as 

possible. For example, you should tell 

us the numbers of the sections or 

paragraphs that are unclearly written, 

which sections or sentences are too 

long, the sections where you feel lists or 

tables would be useful, etc. 

Regulatory Planning and Review 

(Executive Orders 12866, 13563 and 

14094) 

Executive Order 14094 amends and 

reaffirms the principles of E.O. 12866 

and E.O. 13563 and states that 

regulatory analysis should facilitate 

agency efforts to develop regulations 

that serve the public interest, advance 

statutory objectives, and are consistent 

with E.O.s 12866, 13563, and 14094. 

Regulatory analysis, as practicable and 

appropriate, shall recognize distributive 

impacts and equity, to the extent 

permitted by law. E.O. 13563 

emphasizes further that regulations 

must be based on the best available 

science and that the rulemaking process 

must allow for public participation and 

an open exchange of ideas. We have 

developed this proposed rule in a 

manner consistent with these 

requirements. 

Regulatory Flexibility Act (5 U.S.C. 601 

et seq.) 

Under the Regulatory Flexibility Act 

(RFA; 5 U.S.C. 601 et seq.), as amended 

by the Small Business Regulatory 

Enforcement Fairness Act of 1996 

(SBREFA; title II of Pub. L. 104–121, 

March 29, 1996.), whenever an agency 

is required to publish a notice of 

rulemaking for any proposed or final 

rule, it must prepare and make available 

for public comment a regulatory 

flexibility analysis that describes the 

effects of the rule on small entities (i.e., 

small businesses, small organizations, 

and small government jurisdictions). 

However, no regulatory flexibility 

analysis is required if the head of the 

agency certifies the rule will not have a 

significant economic impact on a 

substantial number of small entities. 

The SBREFA amended the RFA to 

require Federal agencies to provide a 

certification statement of the factual 

basis for certifying that the rule will not 

have a significant economic impact on 

a substantial number of small entities. 

According to the Small Business 

Administration, small entities include 

small organizations such as 

independent nonprofit organizations; 

small governmental jurisdictions, 

including school boards and city and 

town governments that serve fewer than 

50,000 residents; and small businesses 

(13 CFR 121.201). Small businesses 

include manufacturing and mining 

concerns with fewer than 500 

employees, wholesale trade entities 

with fewer than 100 employees, retail 

and service businesses with less than $5 

million in annual sales, general and 

heavy construction businesses with less 

than $27.5 million in annual business, 

special trade contractors doing less than 

$11.5 million in annual business, and 

agricultural businesses with annual 

sales less than $750,000. To determine 

whether potential economic impacts to 

these small entities are significant, we 

considered the types of activities that 

might trigger regulatory impacts under 

this designation as well as types of 

project modifications that may result. In 

general, the term ‘‘significant economic 

impact’’ is meant to apply to a typical 

small business firm’s business 

operations. 

Under the RFA, as amended, as 

understood in light of recent court 

decisions, Federal agencies are required 

to evaluate the potential incremental 

impacts of rulemaking on those entities 

directly regulated by the rulemaking 

itself; in other words, the RFA does not 

require agencies to evaluate the 

potential impacts to indirectly regulated 

entities. The regulatory mechanism 

through which critical habitat 

protections are realized is section 7 of 

the Act, which requires Federal 

agencies, in consultation with the 

Service, to ensure that any action 

authorized, funded, or carried out by the 

agency is not likely to destroy or 

adversely modify critical habitat. 

Therefore, under section 7, only Federal 

action agencies are directly subject to 

the specific regulatory requirement 

(avoiding destruction and adverse 

modification) imposed by critical 

habitat designation. Consequently, only 


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Federal action agencies would be 

directly regulated if we adopt the 

proposed critical habitat designation. 

The RFA does not require evaluation of 

the potential impacts to entities not 

directly regulated. Moreover, Federal 

agencies are not small entities. 

Therefore, because no small entities 

would be directly regulated by this 

rulemaking, the Service certifies that, if 

made final as proposed, the proposed 

critical habitat designation will not have 

a significant economic impact on a 

substantial number of small entities. 

In summary, we have considered 

whether the proposed designation 

would result in a significant economic 

impact on a substantial number of small 

entities. For the above reasons and 

based on currently available 

information, we certify that, if made 

final, the proposed critical habitat 

designation would not have a significant 

economic impact on a substantial 

number of small business entities. 

Therefore, an initial regulatory 

flexibility analysis is not required. 

Energy Supply, Distribution, or Use— 

Executive Order 13211 

E.O. 13211 (Actions Concerning 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use) 

requires agencies to prepare statements 

of energy effects to the extent permitted 

by law when undertaking actions 

identified as significant energy actions 

(66 FR 28355, May 22, 2001). E.O. 13211 

defines a ‘‘significant energy action’’ as 

an action that (i) meets the definition of 

a ‘‘significant regulatory action’’ under 

E.O. 12866, as amended by E.O. 14094, 

and (ii) is likely to have a significant 

adverse effect on the supply, 

distribution, or use of energy. In our 

economic analysis, we did not find that 

this proposed critical habitat 

designation would significantly affect 

energy supplies, distribution, or use. 

Therefore, this action is not a significant 

energy action, and no statement of 

energy effects is required. 

Unfunded Mandates Reform Act (2 

U.S.C. 1501 et seq.) 

In accordance with the Unfunded 

Mandates Reform Act (2 U.S.C. 1501 et 

seq.), we make the following finding: 

(1) This proposed rule would not 

produce a Federal mandate. In general, 

a Federal mandate is a provision in 

legislation, statute, or regulation that 

would impose an enforceable duty upon 

State, local, or Tribal governments, or 

the private sector, and includes both 

‘‘Federal intergovernmental mandates’’ 

and ‘‘Federal private sector mandates.’’ 

These terms are defined in 2 U.S.C. 

658(5)–(7). ‘‘Federal intergovernmental 

mandate’’ includes a regulation that 

‘‘would impose an enforceable duty 

upon State, local, or Tribal 

governments’’ with two exceptions. It 

excludes ‘‘a condition of Federal 

assistance.’’ It also excludes ‘‘a duty 

arising from participation in a voluntary 

Federal program,’’ unless the regulation 

‘‘relates to a then-existing Federal 

program under which $500,000,000 or 

more is provided annually to State, 

local, and Tribal governments under 

entitlement authority,’’ if the provision 

would ‘‘increase the stringency of 

conditions of assistance’’ or ‘‘place caps 

upon, or otherwise decrease, the Federal 

Government’s responsibility to provide 

funding,’’ and the State, local, or Tribal 

governments ‘‘lack authority’’ to adjust 

accordingly. At the time of enactment, 

these entitlement programs were 

Medicaid; Aid to Families with 

Dependent Children work programs; 

Child Nutrition; Food Stamps; Social 

Services Block Grants; Vocational 

Rehabilitation State Grants; Foster Care, 

Adoption Assistance, and Independent 

Living; Family Support Welfare 

Services; and Child Support 

Enforcement. ‘‘Federal private sector 

mandate’’ includes a regulation that 

‘‘would impose an enforceable duty 

upon the private sector, except (i) a 

condition of Federal assistance or (ii) a 

duty arising from participation in a 

voluntary Federal program.’’ 

The designation of critical habitat 

does not impose a legally binding duty 

on non-Federal Government entities or 

private parties. Under the Act, the only 

regulatory effect is that Federal agencies 

must ensure that their actions are not 

likely to destroy or adversely modify 

critical habitat under section 7. While 

non-Federal entities that receive Federal 

funding, assistance, or permits, or that 

otherwise require approval or 

authorization from a Federal agency for 

an action, may be indirectly impacted 

by the designation of critical habitat, the 

legally binding duty to avoid 

destruction or adverse modification of 

critical habitat rests squarely on the 

Federal agency. Furthermore, to the 

extent that non-Federal entities are 

indirectly impacted because they 

receive Federal assistance or participate 

in a voluntary Federal aid program, the 

Unfunded Mandates Reform Act would 

not apply, nor would critical habitat 

shift the costs of the large entitlement 

programs listed above onto State 

governments. 

(2) We do not believe that this 

proposed rule would significantly or 

uniquely affect small governments, 

because the lands being proposed for 

critical habitat designation are owned 

by the New Mexico State Parks, BLM, 

BOR, and the Service’s NWR System. 

None of these government entities fits 

the definition of ‘‘small government 

jurisdiction.’’ Therefore, a small 

government agency plan is not required. 

Takings—Executive Order 12630 

In accordance with E.O. 12630 

(Government Actions and Interference 

with Constitutionally Protected Private 

Property Rights), we have analyzed the 

potential takings implications of 

designating critical habitat for Pecos 

pupfish in a takings implications 

assessment. The Act does not authorize 

the Services to regulate private actions 

on private lands or confiscate private 

property as a result of critical habitat 

designation. Designation of critical 

habitat does not affect land ownership, 

or establish any closures, or restrictions 

on use of or access to the designated 

areas. Furthermore, the designation of 

critical habitat does not affect 

landowner actions that do not require 

Federal funding or permits, nor does it 

preclude development of habitat 

conservation programs or issuance of 

incidental take permits to permit actions 

that do require Federal funding or 

permits to go forward. However, Federal 

agencies are prohibited from carrying 

out, funding, or authorizing actions that 

would destroy or adversely modify 

critical habitat. A takings implications 

assessment has been completed for the 

proposed designation of critical habitat 

for Pecos pupfish, and it concludes that, 

if adopted, this designation of critical 

habitat does not pose significant takings 

implications for lands within or affected 

by the designation. 

Federalism—Executive Order 13132 

In accordance with E.O. 13132 

(Federalism), this proposed rule does 

not have significant federalism effects. 

A federalism summary impact statement 

is not required. In keeping with 

Department of the Interior and 

Department of Commerce policy, we 

requested information from, and 

coordinated development of this 

proposed critical habitat designation 

with, appropriate State resource 

agencies. From a federalism perspective, 

the designation of critical habitat 

directly affects only the responsibilities 

of Federal agencies. The Act imposes no 

other duties with respect to critical 

habitat, either for States and local 

governments, or for anyone else. As a 

result, the proposed rule does not have 

substantial direct effects either on the 

States, or on the relationship between 

the Federal Government and the States, 

or on the distribution of powers and 

responsibilities among the various 

levels of government. The proposed 


ddrumheller on DSK120RN23PROD with PROPOSALS2
92778 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

designation may have some benefit to 

these governments because the areas 

that contain the features essential to the 

conservation of the species are more 

clearly defined, and the physical or 

biological features of the habitat 

necessary for the conservation of the 

species are specifically identified. This 

information does not alter where and 

what federally sponsored activities may 

occur. However, it may assist State and 

local governments in long-range 

planning because they no longer have to 

wait for case-by-case section 7 

consultations to occur. 

Where State and local governments 

require approval or authorization from a 

Federal agency for actions that may 

affect critical habitat, consultation 

under section 7(a)(2) of the Act would 

be required. While non-Federal entities 

that receive Federal funding, assistance, 

or permits, or that otherwise require 

approval or authorization from a Federal 

agency for an action, may be indirectly 

impacted by the designation of critical 

habitat, the legally binding duty to 

avoid destruction or adverse 

modification of critical habitat rests 

squarely on the Federal agency. 

Civil Justice Reform—Executive Order 

12988 

In accordance with E.O. 12988 (Civil 

Justice Reform), the Office of the 

Solicitor has determined that the rule 

would not unduly burden the judicial 

system and that it meets the 

requirements of sections 3(a) and 3(b)(2) 

of the order. We have proposed 

designating critical habitat in 

accordance with the provisions of the 

Act. To assist the public in 

understanding the habitat needs of the 

species, this proposed rule identifies the 

physical or biological features essential 

to the conservation of the species. The 

proposed areas of critical habitat are 

presented on maps, and the proposed 

rule provides several options for the 

interested public to obtain more 

detailed location information, if desired. 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3501 et seq.) 

This proposed rule does not contain 

information collection requirements, 

and a submission to the Office of 

Management and Budget (OMB) under 

the Paperwork Reduction Act of 1995 

(44 U.S.C. 3501 et seq.) is not required. 

We may not conduct or sponsor and you 

are not required to respond to a 

collection of information unless it 

displays a currently valid OMB control 

number. 

National Environmental Policy Act (42 

U.S.C. 4321 et seq.) 

Regulations adopted pursuant to 

section 4(a) of the Act are exempt from 

the National Environmental Policy Act 

(NEPA; 42 U.S.C. 4321 et seq.) and do 

not require an environmental analysis 

under NEPA. We published a rulerelated notice outlining our reasons for 

this determination in the Federal 

Register on October 25, 1983 (48 FR 

49244). This includes listing, delisting, 

and reclassification rules, as well as 

critical habitat designations and speciesspecific protective regulations 

promulgated concurrently with a 

decision to list or reclassify a species as 

threatened. The courts have upheld this 

position (e.g., Douglas County v. 

Babbitt, 48 F.3d 1495 (9th Cir. 1995) 

(critical habitat); Center for Biological 

Diversity v. U.S. Fish and Wildlife 

Service, 2005 WL 2000928 (N.D. Cal. 

Aug. 19, 2005) (concurrent 4(d) rule)). 

However, when we designate as 

‘‘critical habitat’’ any of the areas that 

fall within the jurisdiction of the U.S. 

Court of Appeals for the Tenth Circuit, 

including this designation proposed for 

the Pecos pupfish, we undertake a 

NEPA analysis for that critical habitat 

designation consistent with the Tenth 

Circuit’s ruling in Catron County Board 

of Commissioners v. U.S. Fish and 

Wildlife Service, 75 F.3d 1429 (10th Cir. 

1996). We invite the public to comment 

on the extent to which this proposed 

critical habitat designation may have a 

significant impact on the human 

environment, or fall within one of the 

categorical exclusions for actions that 

have no individual or cumulative effect 

on the quality of the human 

environment. We will complete our 

analysis, in compliance with NEPA, 

before finalizing this proposed rule. 

Government-to-Government 

Relationship With Tribes 

In accordance with the President’s 

memorandum of April 29, 1994 

(Government-to-Government Relations 

with Native American Tribal 

Governments; 59 FR 22951, May 4, 

1994), E.O. 13175 (Consultation and 

Coordination with Indian Tribal 

Governments), the President’s 

memorandum of November 30, 2022 

(Uniform Standards for Tribal 

Consultation; 87 FR 74479, December 5, 

2022), and the Department of the 

Interior’s manual at 512 DM 2, we 

readily acknowledge our responsibility 

to communicate meaningfully with 

federally recognized Tribes and Alaska 

Native Corporations (ANCs) on a 

government-to-government basis. In 

accordance with Secretary’s Order 3206 

of June 5, 1997 (American Indian Tribal 

Rights, Federal-Tribal Trust 

Responsibilities, and the Endangered 

Species Act), we readily acknowledge 

our responsibilities to work directly 

with Tribes in developing programs for 

healthy ecosystems, to acknowledge that 

Tribal lands are not subject to the same 

controls as Federal public lands, to 

remain sensitive to Indian culture, and 

to make information available to Tribes. 

We will continue to work with relevant 

Tribal entities during the development 

of any final rules for the Pecos pupfish. 

We have determined that no Tribal 

lands fall within the boundaries of the 

proposed critical habitat for the Pecos 

pupfish, so no Tribal lands would be 

affected by the proposed designation. 

References Cited 

A complete list of references cited in 

this rulemaking is available on the 

internet at https://www.regulations.gov 

and upon request from the New Mexico 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Authors 

The primary authors of this proposed 

rule are the staff members of the Fish 

and Wildlife Service’s Species 

Assessment Team and the New Mexico 

Ecological Services Field Office. 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Plants, Reporting and 

recordkeeping requirements, 

Transportation, Wildlife. 

Proposed Regulation Promulgation 

Accordingly, we propose to amend 

part 17, subchapter B of chapter I, title 

50 of the Code of Federal Regulations, 

as set forth below: 

PART 17—ENDANGERED AND 

THREATENED WILDLIFE AND PLANTS 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361–1407; 1531– 

1544; and 4201–4245, unless otherwise 

noted. 

■ 2. In § 17.11, in paragraph (h), amend 

the List of Endangered and Threatened 

Wildlife by adding an entry for 

‘‘Pupfish, Pecos’’ in alphabetical order 

under FISHES to read as follows: 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 


ddrumheller on DSK120RN23PROD with PROPOSALS2
Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 92779 

Common name Scientific name Where listed Status Listing citations and applicable rules 

*******

FISHES

*******

Pupfish, Pecos ............................ Cyprinodon pecosensis ............. Wherever found ......................... T [Federal Register citation when published as a 

final rule]; 50 CFR 17.44(bb); 4d 50 CFR 

17.95(e).CH

* * * * * * * 

■ 3. In § 17.44, add paragraph (bb) to 

read as follows: 

§ 17.44 Species-specific rules—fishes. 

* * * * * 

(bb) Pecos pupfish (Cyprinodon 

pecosensis)—(1) Prohibitions. The 

following prohibitions that apply to 

endangered wildlife also apply to Pecos 

pupfish. Except as provided under 

paragraph (bb)(2) of this section and 

§§ 17.4 and 17.5, it is unlawful for any 

person subject to the jurisdiction of the 

United States to commit, to attempt to 

commit, to solicit another to commit, or 

cause to be committed, any of the 

following acts in regard to this species: 

(i) Import or export, as set forth at 

§ 17.21(b) for endangered wildlife. 

(ii) Take, as set forth at § 17.21(c)(1) 

for endangered wildlife. 

(iii) Possession and other acts with 

unlawfully taken specimens, as set forth 

at § 17.21(d)(1) for endangered wildlife. 

(iv) Interstate or foreign commerce in 

the course of a commercial activity, as 

set forth at § 17.21(e) for endangered 

wildlife. 

(v) Sale or offer for sale, as set forth 

at § 17.21(f) for endangered wildlife. 

(2) Exceptions from prohibitions. In 

regard to this species, you may: 

(i) Conduct activities as authorized by 

a permit under § 17.32. 

(ii) Take, as set forth at § 17.21(c)(2) 

through (c)(4) for endangered wildlife. 

(iii) Take, as set forth at § 17.31(b). 

(iv) Possess and engage in other acts 

with unlawfully taken wildlife, as set 

forth at § 17.21(d)(2) for endangered 

wildlife. 

(v) Take incidental to an otherwise 

lawful activity caused by: 

(A) Management and maintenance of 

ponds that satisfy Texas Parks and 

Wildlife Department (TPWD) permitting 

requirements and are stocked by TPWD 

with captive-bred Pecos pupfish. 

(B) Research activities conducted by 

holders of a valid scientific research 

permit, zoological permit, or 

educational display permit issued by 

TPWD on individual Pecos pupfish in 

ponds that are part of the TPWD Pecos 

pupfish production effort. Researchers 

must report annually to TPWD, and 

TPWD must annually report to the 

Service, the following information: 

(1) The nature of research performed; 

(2) The dates of fieldwork; 

(3) The number of individuals 

collected or captured and the methods 

used to obtain them; 

(4) A description of any accidental 

injuries or mortalities; and 

(5) 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. 

* * * * * 

■ 4. In § 17.95, in paragraph (e), add an 

entry for ‘‘Pecos Pupfish (Cyprinodon 

pecosensis)’’ after the entry for ‘‘Leon 

Springs Pupfish (Cyprinodon bovinus)’’, 

to read as follows: 

§ 17.95 Critical habitat—fish and wildlife. 

* * * * * 

(e) Fishes. 

* * * * * 

Pecos Pupfish (Cyprinodon pecosensis) 

(1) Critical habitat units are depicted 

for Chaves and Eddy Counties, New 

Mexico, and Culberson and Reeves 

Counties, Texas, on the maps in this 

entry. 

(2) Within these areas, the physical or 

biological features essential to the 

conservation of Pecos pupfish consist of 

the following components: 

(i) Water quality parameters that 

support all life stages of the Pecos 

pupfish, including: 

(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 °C 

(108.9 °F); and 

(D) Dissolved oxygen greater than 2.5 

mg/L. 

(ii) Sufficient water quantity 

parameters that support all life stages of 

the Pecos pupfish, including: 

(A) Permanent water in a portion of 

the habitat; and 

(B) Water depth less than 2 m (6.56 ft) 

deep to allow for thermal refugia and 

breeding. 

(iii) Presence of silt-free underwater 

features such as crevices, boulders, large 

rocks, scattered pebbles, and aquatic 

plants that are used for egg deposition. 

(iv) Absence of nonnative invasive 

sheepshead minnow. 

(3) Critical habitat does not include 

manmade structures (such as buildings, 

aqueducts, runways, roads, and other 

paved areas) and the land on which they 

are located existing within the legal 

boundaries on the effective date of the 

final rule. 

(4) Data layers defining map units 

were created using ESRI OpenStreets 

and Imagery basemaps, USA Federal 

Lands data, and the National 

Hydrography Dataset (NHD) Plus 

dataset. Polygons for units 2, 3, and 4 

were largely defined through heads-up 

digitization or land ownership 

boundaries (Unit 3, Bitter Lake NWR); 

acreage or mileage numbers in the 

designation came from these features. 

For online distribution, linear features 

in Unit 1 (the Pecos River) and Unit 5 

(Salt Creek) were converted to polygons. 

We used NHD polygons when available. 

When polygons were unavailable, we 

buffered the linear features by a set 

distance; 20 m for the lower third of 

unit 1, and 5 m for the entirety of unit 

5. The boundaries of units 2, 3, and 4 

that abutted the Pecos River were 

adjusted to match the new Unit 1 

polygon. The maps in this entry, as 

modified by any accompanying 

regulatory text, establish the boundaries 

of the critical habitat designation. The 

coordinates or plot points or both on 

which each map is based are available 

to the public at https://

www.regulations.gov under Docket No. 

FWS–R2–ES–2024–0143 and at the field 

office responsible for this designation. 

You may obtain field office location 

information by contacting one of the 

Service regional offices, the addresses of 

which are listed at 50 CFR 2.2. 

(5) Index map follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2
92780 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

Figure 1 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (5) 

BILLING CODE 4333–15–P 

BILLING CODE 4333–15–C 

(6) Unit 1: Upper Pecos River, Chaves 

and Eddy Counties, New Mexico. 

(i) Unit 1 consists of 121.88 river mi 

(196.15 km) of the upper Pecos River in 

Chaves and Eddy Counties, New 

Mexico, and is composed of lands in 

Federal (32.61 river mi (52.48 km)), 

State (4.86 river mi (7.82 km)), and 

private (84.41 river mi (135.84 km)) 

ownership. Unit 1 includes river habitat 

up to bank full height. 

(ii) Map of Unit 1 follows: 

Figure 2 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (6)(ii) 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.003</GPH>

Critical Habitat for Pecos Pupfish - Unit Overview 

: .... ,.._ ." .. ~" ·', 

tl.riifi:s~kc:r~ek•Wnd~t'riess' ... ; ... ,.~ }·~:\~.~·,-~ .. ~~. ':. 

l 

Unit ( Bottomlesslak~sJ 

BLM.•··· \:Overflow Wetlands . ,i ' '•' ' 

CU!br!FSOIF•···'·•· 

rour•r;',.'' 

Unit 5'" ~ ~.ltcreek (TX}.~J Reeve, ·:•'=.--"="<•-~.; ~--~.,:-:-, 

- trltkal Habitat 

-----' River/Q'eek 

Q 10 20Mi l I r 1 'l 

D 1ti 20Km 

Lake I Reservoir 

□. City 

CJ State BQUnd,'iry 
Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 92781 

BILLING CODE 4333–15–C 

(7) Unit 2: Salt Creek Wilderness, 

Chaves County, New Mexico. 

(i) Unit 2 contains Salt Creek (New 

Mexico) and four sinkholes within 

5,428.74 acres (2,196.93 hectares (ha)) of 

land in Chaves County, New Mexico. 

The wetted areas within this unit are 

entirely under Federal ownership, 

specifically the Service’s Bitter Lake 

National Wildlife Refuge (NWR). 

(ii) Map of Unit 2 follows: 

Figure 3 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (7)(ii) 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.004</GPH>

NEW 

MEXICO. 

3 • Bitter 

0 

I I 

0 

N 

A 

10 20 Ml 

I I I I 

W 20Km 

. (:f\NX.'.H'l\? ... 

nit 4. - Bottomless Lal-<e•s/.: I . BLM Overflow Wetlands 

U mt ' 1 U P .. pper ec:os I R' aver 

- Critical Habitat - Unit 1 

Critical Habitat· other Units 

• - " River / Creek 

/ RE!!ierYOlr 

Road 
92782 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

BILLING CODE 4333–15–C 

(8) Unit 3: Bitter Lake, Chaves County, 

New Mexico. 

(i) Unit 3 contains Bitter Creek and 

numerous isolated sinkholes, spring 

ditches, managed and natural wetlands, 

and oxbows of the Pecos River within 

11,972.90 acres (4,845.26 ha) of Chaves 

County, New Mexico. The unit is 

composed of lands in Federal (9,663.15 

acres (3,910.54 ha)), State (87.87 acres 

(35.56 ha)), and private (2,221.88 acres 

(899.16 ha)) ownership. 

(ii) Map of Unit 3 follows: 

Figure 4 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (8)(ii) 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.005</GPH>

Wilderness 

Unit 3 

1 r-~-----,,--.. 7 

It/ NEW J I 

MfXICO 1 1 l • i I 

I I l1-~~:•-, . .___J 

\ TEX.AS 

\;--, 

A 

0 2 4Mi 

D 4Km 

(μnit 1 - Upper Pecos River 

- Crltical Habitat - Unit 2 

!iii Critical Habitat - Other Units 

Bitlt!r Ldke NWR 

River/ Creek 

Road 
Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 92783 

BILLING CODE 4333–15–C 

(9) Unit 4: Overflow Wetlands/ 

Bottomless Lakes, Chaves County, New 

Mexico. 

(i) Unit 4 contains a wetland and 

several isolated sinkholes within 

9,153.90 acres (3,704.45 ha) in Chaves 

County, New Mexico. The unit is 

composed of lands in Federal (1,784 

acres (721.96 ha)), State (1854.78 acres 

(750.60 ha)), and private (5,515.12 acres 

(2,231.89 ha)) ownership. 

(ii) Map of Unit 4 follows: 

Figure 5 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (9)(ii) 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.006</GPH>

Unit 3 - Bitter Lak~ • 

[,""" 

1: 

0 1 S 3 Mi 

1 - Upper Pecos River 

om!ess Lakes / 

Wetlands 

- Critical Habitat - Unit 3 

Critical Habitat - Other Units 

Bitter Lilkl~ NWR 

River / Creek 

Road 

Cl City 
92784 Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 

BILLING CODE 4333–15–C 

(10) Unit 5: Salt Creek (TX), in 

Culberson and Reeves Counties, Texas. 

(i) Unit 5 consists of 14.24 river mi 

(23.20 km) in Culberson and Reeves 

Counties, Texas, and is composed of 

lands in 100 percent private ownership. 

Unit 5 includes river habitat up to bank 

full height. 

(ii) Map of Unit 5 follows: 

Figure 6 to Pecos Pupfish (Cyprinodon 

pecosensis) paragraph (10)(ii) 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.007</GPH>

NEW 

MEXICO 

• 

TEXAS 

0 

Unit 4 - Bottomless l~kes / 

BLM Overflow Wetlands 

2Km 

River / Creek 

Road 

D cn:y 
Federal Register / Vol. 89, No. 226 / Friday, November 22, 2024 / Proposed Rules 92785 

BILLING CODE 4333–15–C 

* * * * * 

Martha Williams, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2024–27127 Filed 11–21–24; 8:45 am] 

BILLING CODE 4333–15–P 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP22NO24.008</GPH>

NE\'\/ MEXICO 

TEXAS 

I 

NEW I 

fv1EXICO / 

. I 

-~--~·-·a-J 

'\ '\ TEXAS 

Critical Habitat for Pecos Pupfish 

Unit 5: Salt Creek (TX) 

Culberson and Reeves Counties, Texas 

Unit 5 • Salt Creek (TX) 

- Critical - Unit 5 

Mi 

River / Creek 

Lake/ 

Road 

Clty 

County £-loundary 

Stat.e Boundary