64870 Federal Register / Vol. 88, No. 181 / Wednesday, September 20, 2023 / Proposed Rules 

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

*******

CRUSTACEANS

* * * * * * * 

Crayfish, Miami cave ......... Procambarus milleri .......... Wherever found ................ T [Federal Register citation when published as a final rule]; 50 CFR 

17.46(e); 4d

* * * * * * * 

■ 3. Amend § 17.46 by adding 

paragraph (e) to read as follows: 

§ 17.46 Special rules—crustaceans. 

* * * * * 

(e) Miami cave crish (Procambarus 

milleri). 

(1) Prohibitions. The following 

prohibitions that apply to endangered 

wildlife also apply to the Miami cave 

crayfish. Except as provided under 

paragraph (e)(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 (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) Activities that will prevent further 

saltwater intrusion into the Biscayne 

Aquifer, such as coastal resiliency 

projects and canal maintenance or 

construction that prevent backflow of 

salt water; or 

(B) Water management activities or 

coastal wetland restoration projects that 

improve freshwater and estuarine 

habitats; improve salinity distribution 

and reestablish productive nursery 

habitat along the shoreline; restore the 

quantity, quality, timing, and 

distribution of freshwater to Biscayne 

Bay and Biscayne National Park; restore 

the spatial extent of natural coastal 

glades habitat; or enhance natural 

infiltration into the Biscayne Aquifer. 

Martha Williams, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2023–20293 Filed 9–19–23; 8:45 am] 

BILLING CODE 4333–15–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[FF09E21000 FXES1111090FEDR 234] 

Endangered and Threatened Wildlife 

and Plants; One Species Not 

Warranted for Delisting and Six 

Species Not Warranted for Listing as 

Endangered or Threatened Species 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Notification of findings. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce 

findings that one species is not 

warranted for delisting and six species 

are not warranted for listing as 

endangered or threatened species under 

the Endangered Species Act of 1973, as 

amended (Act). After a thorough review 

of the best available scientific and 

commercial information, we find that it 

is not warranted at this time to delist the 

southern sea otter (Enhydra lutris 

nereis). We also find that is not 

warranted at this time to list the 

Cascades frog (Rana cascadae), plains 

spotted skunk (Spilogale interrupta, 

formerly recognized as one of three 

subspecies of eastern spotted skunk 

(Spilogale putorius interrupta)), 

sicklefin chub (Macrhybopsis meeki), 

sturgeon chub (Macrhybopsis gelida), 

Tennessee cave salamander 

(Gyrinophilus palleucus), and Yazoo 

crayfish (Faxonius hartfieldi, formerly 

Orconectes hartfieldi). However, we ask 

the public to submit to us at any time 

any new information relevant to the 

status of any of the species mentioned 

above or their habitats. 

DATES: The findings in this document 

were made on September 20, 2023. 

ADDRESSES: Detailed descriptions of the 

bases for these findings are available on 

the internet at https://

www.regulations.gov under the 

following docket numbers: 

Species Docket No. 

Cascades frog .......... FWS–R1–ES–2023– 

0127. 

Plains spotted skunk FWS–R3–ES–2023– 

0128. 

Sicklefin chub ........... FWS–R6–ES–2023– 

0130. 

Southern sea otter .... FWS–R8–ES–2023– 

0132. 

Sturgeon chub .......... FWS–R6–ES–2023– 

0131. 

Tennessee cave salamander.FWS–R4–ES–2023– 

0133. 

Yazoo crayfish .......... FWS–R4–ES–2023– 

0134. 

Those descriptions are also available 

by contacting the appropriate person as 

specified under FOR FURTHER

INFORMATION CONTACT. Please submit any 

new information, materials, comments, 

or questions concerning this finding to 

the appropriate person, as specified 

under FOR FURTHER INFORMATION

CONTACT. 

FOR FURTHER INFORMATION CONTACT: 

Species Contact information 

Cascades frog ................................. Jeff Dillon, Endangered Species Division Manager, Oregon Fish and Wildlife Office, jeffrey_dillon@fws.gov, 

503–231–6179. 

Plains spotted skunk ....................... John Weber, Field Supervisor, Missouri Field Office, John_S_Weber@fws.gov, 573–825–6048. 


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Species Contact information 

Sicklefin chub and sturgeon chub .. Amity Bass, Field Supervisor, North and South Dakota Ecological Services, amity_bass@fws.gov, 605– 

222–0228. 

Southern sea otter .......................... Steve Henry, Field Supervisor, Ventura Fish and Wildlife Office, steve_henry@fws.gov, 805–644–1766. 

Tennessee cave salamander .......... Dan Elbert, Field Supervisor, Tennessee FO, daniel_elbert@fws.gov, 571–461–8964. 

Yazoo crayfish ................................ James Austin, Field Supervisor, Mississippi Ecological Field Office, 601–321–1129, james_austin@

fws.gov. 

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. 

SUPPLEMENTARY INFORMATION: 

Background 

Under section 4(b)(3)(B) of the Act (16 

U.S.C. 1531 et seq.), we are required to 

make a finding on whether or not a 

petitioned action is warranted within 12 

months after receiving any petition that 

we have determined contains 

substantial scientific or commercial 

information indicating that the 

petitioned action may be warranted 

(hereafter a ‘‘12-month finding’’). We 

must make a finding that the petitioned 

action is: (1) Not warranted; (2) 

warranted; or (3) warranted but 

precluded by other listing activity. We 

must publish a notification of these 12- 

month findings in the Federal Register. 

Summary of Information Pertaining to 

the Five Factors 

Section 4 of the Act (16 U.S.C. 1533) 

and the implementing regulations at 

part 424 of title 50 of the Code of 

Federal Regulations (50 CFR part 424) 

set forth procedures for adding species 

to, removing species from, or 

reclassifying species on the Lists of 

Endangered and Threatened Wildlife 

and Plants (Lists). The Act defines 

‘‘species’’ as including any subspecies 

of fish or wildlife or plants, and any 

distinct population segment of any 

species of vertebrate fish or wildlife 

which interbreeds when mature (16 

U.S.C. 1532(16)). The Act defines 

‘‘endangered species’’ as any species 

that is in danger of extinction 

throughout all or a significant portion of 

its range (16 U.S.C. 1532(6)), and 

‘‘threatened species’’ as any species that 

is likely to become an endangered 

species within the foreseeable future 

throughout all or a significant portion of 

its range (16 U.S.C. 1532(20)). Under 

section 4(a)(1) of the Act, a species may 

be determined to be an endangered 

species or a threatened species because 

of any of the following 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. 

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 expected response by 

the species, 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 Act’s definition of an 

‘‘endangered species’’ or a ‘‘threatened 

species’’ only after conducting this 

cumulative analysis and describing the 

expected effect on the species now and 

in the foreseeable future. 

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. The term 

‘‘foreseeable future’’ extends only so far 

into the future as we can reasonably 

determine that both the future threats 

and the species’ responses to those 

threats are likely. In other words, the 

foreseeable future is the period of time 

in which we can make reliable 

predictions. ‘‘Reliable’’ does not mean 

‘‘certain’’; it means sufficient to provide 

a reasonable degree of confidence in the 

prediction. Thus, a prediction is reliable 

if it is reasonable to depend on it when 

making decisions. 

It is not always possible or necessary 

to define foreseeable future as a 

particular number of years. Analysis of 

the foreseeable future uses the best 

scientific and commercial data available 

and should consider the timeframes 

applicable to the relevant threats and to 

the species’ responses to those threats in 

view of its life-history characteristics. 

Data that are typically relevant to 

assessing the species’ biological 

response include species-specific factors 

such as lifespan, reproductive rates or 

productivity, certain behaviors, and 

other demographic factors. 

In conducting our evaluation of the 

five factors provided in section 4(a)(1) of 

the Act to determine whether the 

Cascades frog, plains spotted skunk, 

sicklefin chub, southern sea otter, 

sturgeon chub, Tennessee cave 

salamander, and Yazoo crayfish meet 

the Act’s definition of ‘‘endangered 

species’’ or ‘‘threatened species,’’ we 

considered and thoroughly evaluated 

the best scientific and commercial 

information available regarding the past, 

present, and future stressors and threats. 

We reviewed the petitions, information 

available in our files, and other 

available published and unpublished 


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information for all these species. Our 

evaluation may include information 

from recognized experts; Federal, State, 

and Tribal governments; academic 

institutions; foreign governments; 

private entities; and other members of 

the public. 

In accordance with the regulations at 

50 CFR 424.14(h)(2)(i), this document 

announces the not-warranted findings 

on petitions to delist one species and 

list six species. We have also elected to 

include brief summaries of the analyses 

on which these findings are based. We 

provide the full analyses, including the 

reasons and data on which the findings 

are based, in the decisional file for each 

of the seven actions included in this 

document. The following is a 

description of the documents containing 

these analyses: 

The species assessment forms for 

Cascades frog, plains spotted skunk, 

sicklefin chub, sturgeon chub, 

Tennessee cave salamander, and Yazoo 

crayfish contain more detailed 

biological information, a thorough 

analysis of the listing factors, a list of 

literature cited, and an explanation of 

why we determined that each species 

does not meet the Act’s definition of an 

‘‘endangered species’’ or a ‘‘threatened 

species.’’ The species assessment form 

for the southern sea otter contains more 

detailed biological information, a 

thorough analysis of the listing factors, 

a list of literature cited, and an 

explanation of why we determined that 

the species continues to meet the Act’s 

definition of a ‘‘threatened’’ species. To 

inform our status reviews, we 

completed species status assessment 

(SSA) reports for the Cascades frog, 

plains spotted skunk, sicklefin chub, 

southern sea otter, sturgeon chub, 

Tennessee cave salamander, and Yazoo 

crayfish. Each SSA report contains a 

thorough review of the taxonomy, life 

history, ecology, current status, and 

projected future status for each species. 

This supporting information can be 

found on the internet at https://

www.regulations.gov under the 

appropriate docket number (see 

ADDRESSES, above). 

Cascades Frog 

Previous Federal Actions 

On July 11, 2012, we received a 

petition from the Center for Biological 

Diversity to list 53 amphibian and 

reptile species, including Cascades frog 

(Rana cascadae), as an endangered or 

threatened species under the Act. On 

July 1, 2015, we published a 90-day 

finding (80 FR 37568) that the petition 

contained substantial information 

indicating listing may be warranted for 

the species. This document constitutes 

our 12-month finding on the July 11, 

2012, petition to list Cascades frog 

under the Act. 

Summary of Findings 

The Cascades frog is a medium-sized 

frog typically less than 71 millimeters 

(mm) (2.8 inches (in)) in length; males 

are smaller than females. The Cascades 

frog is greenish brown with variation 

among frogs in spot appearance. The 

species is generally associated with 

middle to high elevations 

(approximately 400 to 2,500 meters (m) 

(1,312 to 8,202 feet (ft)); its current and 

historical range extends along the 

Cascade Mountain Range from near the 

United States-Canada border south 

through Washington and Oregon to 

California just south of Lassen Peak. The 

species can also be found within the 

Klamath Mountains of California and 

the Olympic Mountains in Washington. 

The species may be extirpated within 

Lassen Volcanic National Park. 

The Cascades frog is primarily 

aquatic, using lakes, ponds, wet 

meadows, and streams, where they are 

often found along shorelines or on 

emergent rocks or logs. It uses habitats 

that are maintained by cold winters 

with deep snowpack and spring 

snowmelt. A diversity of aquatic 

features is needed to support all life 

stages, breeding, foraging, and dispersal, 

and to provide areas of refuge from 

predators. Precipitation is important in 

supporting aquatic habitats and 

movement of individuals across the 

landscape. The Cascades frog 

overwinters in aerobic sediments at the 

bottom of aquatic features that have 

stable thermal conditions and do not 

completely freeze over. 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the Cascades frog, 

and we evaluated all relevant factors 

under the five listing factors, including 

any regulatory mechanisms and 

conservation measures addressing these 

threats. The primary threats affecting 

the Cascades frog’s biological status 

include climate change, the chytrid 

fungus Batrachochytrium dendrobatidis 

(Bd), and nonnative trout. 

We separated the species’ range into 

five representative units (Olympics, 

Washington Cascades, Oregon Cascades, 

California North, and California South) 

to analyze current and future condition. 

Our current condition analysis finds 

that resiliency of the Cascades frog is 

variable across the range, with all 

representative units having conditions 

to support healthy populations. 

However, the California units are less 

resilient than those in Oregon and 

Washington. The distribution of healthy 

(i.e., good to fair resiliency) populations 

of the species across a broad geographic 

range ensures that catastrophic events 

such as volcanic eruptions, presence of 

Bd, and wildfire are not likely to cause 

risk of Cascades frog extinction. Further, 

the Cascades frog continues to occupy 

historical sites throughout all 

representative units, and factors such as 

habitat, distribution of occurrences, 

connectivity, and natural geological and 

elevational gaps in the range all 

contribute to the species’ overall 

adaptive capacity. Therefore, we 

conclude that Cascades frog is not 

currently in danger of extinction 

throughout all of its range and does not 

meet the Act’s definition of an 

endangered species. 

In considering the foreseeable future 

as it relates to the status of the Cascades 

frog, we considered the relevant risk 

factors (threats/stressors) acting on the 

species and whether we could draw 

reliable predictions about the species’ 

response to these factors. Our analysis 

in the SSA report of future scenarios 

over a an approximately 50-year 

timeframe encompasses the best 

available information for future 

projections of habitat suitability based 

on maximum temperature, minimum 

temperature, precipitation, snow water 

equivalent, soil moisture, and potential 

evapotranspiration under two different 

climate change futures (representative 

concentration pathways (RCP) 4.5 and 

8.5). We determined that this 

approximately 50-year timeframe 

enabled us to consider the threats/ 

stressors acting on the species and draw 

reliable predictions about the species’ 

response to these factors. 

Based on the 3Rs (resiliency, 

representation, and redundancy) 

analyzed in the SSA report, the 

Cascades frog is projected to maintain 

multiple resilient populations, based on 

adequate suitable habitat availability, 

across the landscape for approximately 

50 years into the future. The species is 

expected to withstand both stochastic 

and catastrophic events and have 

sufficient adaptive capacity to endure 

future climate change. Thus, after 

assessing the best available information, 

we conclude that Cascades frog is not 

likely to become endangered within the 

foreseeable future throughout all of its 

range. 

Having determined that the Cascades 

frog is not in danger of extinction or 

likely to become so in the foreseeable 

future throughout all of its range, we 

considered whether it may be in danger 

of extinction or likely to become so in 

the foreseeable future in a significant 


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portion of its range—that is, whether 

there is any portion of the species’ range 

for which it is true that both (1) the 

portion is significant; and (2) the species 

is in danger of extinction now or likely 

to become so in the foreseeable future 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. 

We identified the Olympics and 

California South representative units as 

portions that might have a different 

status than the species rangewide. We 

examined the following threats: climate 

change, Bd, and nonnative trout, 

including cumulative effects. 

The Olympics representative unit has 

fewer analysis units (AUs) (6) than most 

of the other representative units. 

However, the largest AU (unit 15) 

comprises nearly the entire Olympics 

representative unit and contains the 

majority of the Cascades frogs in that 

unit. Currently, this representative unit 

has populations with sufficient 

resiliency to withstand stochastic 

events, and the well-distributed largest 

population, which can be found across 

nearly the entire representation unit 

with good resiliency, is likely to 

withstand catastrophic events. We, 

therefore, determine that the Cascades 

frog is not in danger of extinction in the 

Olympics part of the range. 

The Olympics have more snow-fed 

aquatic systems, indicating that they 

could be more sensitive to climate 

change impacts than habitat in other 

parts of the Cascades frog’s range. 

However, these climate effects depend 

on the kind of wetland habitat affected, 

the distribution of wetland types, and 

the degree of change in hydrologic 

patterns under different future climates. 

We do not know explicit linkages of 

climate effects to specific Cascades frog 

habitat. Despite this caveat, our future 

conditions analysis indicates that the 

largest AU (unit 15), which covers the 

majority of the representation unit, will 

maintain fair habitat suitability across 

all future scenarios. Further, there does 

not appear to be widespread adult 

mortality consistent with Bd in the 

Olympics. While nonnative trout are in 

wetlands of the Washington Olympics 

and will likely continue to be a stressor, 

there are areas within the Olympics 

range (e.g., national parks) where this 

stressor is not likely to exacerbate any 

projected declines. Based on the 

projected future conditions, we 

conclude that the Cascades frog is not in 

danger of extinction within the 

foreseeable future in the Olympics 

portion of its range. 

Populations within the California 

South representative unit have 

experienced declines, local extirpations, 

and low population viability due in part 

to Bd, droughts, nonnative trout 

stocking, and lack of connectivity to 

other habitat. Despite declines in the 

California South part of the range, 75 

percent of the AUs are currently in fair 

condition, indicative of relatively 

healthy populations. These fair 

condition AUs are distributed 

throughout the representative unit, thus 

providing redundancy to both stochastic 

and catastrophic events. We, therefore, 

determine that the Cascades frog is not 

in danger of extinction in the California 

South part of the range. 

Our future conditions analysis shows 

that all AUs within the California South 

representation unit either maintain fair 

habitat condition or improve to good 

habitat condition approximately 50 

years into the future. Although habitat 

suitability is predicted to increase, the 

potential for the Cascades frog to 

colonize suitable habitat is dependent 

on the health of source populations, 

connectivity, and habitat features to 

support the species across all life stages, 

and there is some uncertainty as to the 

extent that this could happen in the 

future. The projected future distribution 

of fair/good condition AUs throughout 

the California South unit provide 

redundancy to stochastic and 

catastrophic events. Based on this 

assessment, we conclude that the 

Cascades frog is not in danger of 

extinction within the foreseeable future 

in the California South portion of its 

range. 

Because we determined that there are 

no portions within the species range 

that are currently in danger of extinction 

or likely to become so in the foreseeable 

future, we do not need to consider 

whether any portion of the range is 

significant. Nonetheless, we did 

undertake this further step for California 

South as a part of our evaluation of 

significant portion of the range. 

Considerations for significance can 

include whether the portion constitutes 

a large geographic area relative to the 

rest of the range, whether the portion 

constitutes habitat of high quality 

relative to the remaining portions of the 

range, or whether the portion 

constitutes high or unique value habitat 

for the species. California South is not 

a large representative unit relative to the 

rest of the range. It does not have unique 

or high value habitat nor high quality 

habitat relative to any other habitat 

throughout the range, and while the 

Lassen Mountains are different from 

other mountains in the range, they 

provide similar habitat features for the 

frogs, and thus they do not result in a 

meaningful difference in the ecology of 

the species. For these reasons, the 

California South portion is not 

considered significant. Therefore, the 

California South portion is not a 

significant portion of the range. 

Thus, after assessing the best available 

information, we conclude that the 

Cascades frog is not in danger of 

extinction or likely to become in danger 

of extinction within the foreseeable 

future throughout all of its range or in 

any significant portion of its range. 

Therefore, we find that listing the 

Cascades frog as an endangered species 

or threatened species under the Act is 

not warranted. 

A detailed discussion of the basis for 

this finding can be found in the 

Cascades frog species assessment form 

and other supporting documents on 

https://www.regulations.gov under 

Docket No. FWS–R1–ES–2023–0127 

(see ADDRESSES, above). 

Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memo on the Peer Review 

Process, we solicited independent 

scientific reviews of the information 

contained in the Cascades frog SSA 

report. The Service sent the SSA report 

to three independent peer reviewers and 

received two responses. Results of this 

structured peer review process can be 

found at https://www.regulations.gov. 

We incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which is the foundation for this 

finding. 

Plains Spotted Skunk 

Previous Federal Actions 

On July 18, 2011, we received a 

petition from Mr. David Wade and Dr. 

Thomas Alton, requesting that multiple 

grassland thicket species or subspecies 

be listed as endangered or threatened 

under the Act, including the plains 

spotted skunk (Spilogale interrupta, 

formerly recognized as one of three 

subspecies of eastern spotted skunk 

(Spilogale putorius interrupta)). On 

December 4, 2012, we published a 90- 

day finding in the Federal Register (77 

FR 71759) concluding that the petition 

presented substantial scientific or 

commercial information indicating that 

listing the plains spotted skunk may be 

warranted. This document constitutes 

our 12-month finding on the July 18, 


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2011, petition to list the plains spotted 

skunk under the Act. 

Summary of Finding 

The plains spotted skunk is a small 

mammal in the weasel family, most 

notable for its vivid black and white fur 

markings, that occurs in a wide range of 

habitat types across the Great Plains 

region of the contiguous United States. 

States with current occurrences 

(observed from 2000 to the present) 

include Arkansas, Iowa, Kansas, 

Minnesota, Missouri, Nebraska, North 

Dakota, Oklahoma, South Dakota, Texas, 

and Wyoming. 

This generalist species exhibits 

relatively high adaptability related to its 

diet and foraging, habitat use, and 

activity patterns. The habitat elements 

that we identified as important to plains 

spotted skunk individuals at each life 

stage include freshwater of sufficient 

quantity, food availability, den 

availability, and habitat complexity that 

provides protective cover. Plains 

spotted skunks are opportunistic 

omnivores, whose diet varies across 

seasons and habitats along with the 

availability and abundance of food 

items. Adult plains spotted skunks are 

typically solitary with the exception of 

mating pairs, females with dependent 

young, and adults denning during cold 

weather for thermoregulation. Despite 

their solitary nature, plains spotted 

skunks show no signs of territoriality. 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the plains spotted 

skunk, and we evaluated all relevant 

factors under the five listing factors, 

including any regulatory mechanisms 

and conservation measures addressing 

these threats. The primary threats 

affecting the plains spotted skunk’s 

biological status include habitat loss 

and fragmentation due to agricultural 

and urban development, and climate 

change. Impacts from climate change 

include exacerbation of drought 

conditions and a decrease of available 

habitat along the Gulf Coast due to sea 

level rise. We also examined a number 

of other factors, including infectious 

pathogens, pesticides, invasive species, 

predation, competition, 

overexploitation, human-wildlife 

conflict, and direct mortality from other 

sources, but these factors did not rise to 

such a level that affected the species as 

a whole. 

To assess the current condition of 

plains spotted skunks we analyzed one 

demographic factor (percent of counties 

with current location) and two habitat 

factors (habitat availability and 

freshwater availability) across six 

population analysis units that cover the 

current range of the species. The 

analysis units cover an extensive range 

with a wide diversity of habitats 

distributed across diverse 

environmental conditions. All analysis 

units had high habitat availability and at 

least moderate freshwater availability. 

The demographic factor scores ranged 

from low (two units) to moderate (four 

units). Largely due to their extensive 

range, plains spotted skunks have a high 

redundancy and are at a low risk for 

experiencing rangewide negative 

impacts from a catastrophic event at a 

given point in time. Similarly, the 

species demonstrates great adaptive 

capacity to adjust to environmental 

change and, thus, currently exhibits 

high representation. 

We evaluated two scenarios to 

characterize the full range of uncertainty 

regarding plausible futures for the 

plains spotted skunk within a 30-year 

timeframe. Resiliency of the six analysis 

units was assessed under each scenario. 

Scenario 1 assumes intermediate to low 

sea level rise, RCP 4.5 emissions, and 

land use changes at 2050 from 

urbanization and agriculture. Scenario 2 

assumes high sea level rise, RCP 8.5 

emissions, and the same land use 

change projections as scenario 1. 

Considering both scenarios, we 

projected the effect of the scenarios on 

two habitat factors important to 

resiliency in the future: habitat 

availability and freshwater availability. 

Under both future scenarios, we 

projected some reduction in freshwater 

availability across the range. Under 

scenario 1, we projected one unit 

scoring low (unit 1) for freshwater 

availability, four scoring moderate 

(units 2–5), and one unit remaining high 

(unit 6). Under scenario 2, we projected 

two units scoring low for freshwater 

availability (units 1 and 3), one scoring 

moderate (unit 2), and three units 

remaining high (units 4–6). Under both 

scenarios, we projected only minimal 

reduction in current habitat availability 

across the range. Under both scenarios, 

we project climate-induced expansion 

of plains spotted skunks into new 

habitats and regions, especially for 

analysis units 1, 2, and 3. For habitat 

availability under both scenarios, we 

project five units (units 1–5) to retain 

high habitat availability and one unit 

(unit 6) to have moderate habitat 

availability. This reduction from 

currently high habitat availability in 

unit 6 to moderate in the future is 

attributed to sea level rise on the Gulf 

Coast of Texas. In either future scenario, 

we expect most analysis units to have 

high to moderate resiliency in terms of 

the habitat factors important to the 

viability of the plains spotted skunk. 

Based on an evaluation of the plausible 

catastrophes likely to adversely impact 

plains spotted skunk populations in 

2050, we predict the species will 

maintain high redundancy in both 

future scenarios. Similarly, our analyses 

of the species’ adaptative capacity based 

on scenarios 1 and 2 support the 

likelihood that the species will continue 

to exhibit high representation 30 years 

into the future. 

The plains spotted skunk is a 

generalist species that eats a wide 

variety of foods and lives in a wide 

variety of habitats across six analysis 

units that extend across many U.S. 

States. Current resiliency, redundancy, 

and representation are all ranked as 

moderate to high. Although there is low 

distribution in two analysis units, the 

species’ resiliency overall is moderate to 

high. The species exhibits high 

redundancy, greatly reducing the 

potential for catastrophic events to 

impact the species at the population 

level, and the species’ high 

representation indicates a high capacity 

to adapt to changing environments. 

There are no identified threats currently 

affecting the species’ viability across its 

range. Based on this information, the 

plains spotted skunk is not in danger of 

extinction throughout all of its range. 

The 3Rs analysis in the SSA report 

provides evidence that the 30-year 

outlook for the species’ projected 

condition under two future scenarios is 

still moderate to high. For resiliency, 

there is almost no change in habitat 

availability except for analysis unit 6 

(the smallest unit) due to sea level rise. 

Freshwater availability drops under 

both scenarios, but only two analysis 

units are projected to be in low 

condition, although one of those is 

analysis unit 3, the largest unit. No units 

ranked ‘‘extremely low’’ under any 

future scenarios. Redundancy and 

representation are projected to be in the 

moderate to high range under both 

future scenarios. Based on this analysis, 

the species is not likely to become 

endangered in the foreseeable future. 

We also evaluated the range of the 

plains spotted skunk to determine if the 

species is in danger of extinction now 

or likely to become so within the 

foreseeable future in any significant 

portion of its range. Although there is 

currently low distribution in two 

analysis units, the habitat and 

freshwater availability in those units is 

high to moderate, and there are no 

barriers to movement or distribution 

(other than the Mississippi River on the 

eastern border of its range). No threats 

have been identified that are currently 


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affecting any portion of the species’ 

range. Two units are projected to be in 

low condition for freshwater availability 

in the future, and sea level rise is 

predicted to decrease habitat availability 

in another unit. However, we do not 

expect freshwater availability to be low 

enough to be limiting, and given the 

retention of high habitat availability, we 

expect these units to support the species 

in the foreseeable future, especially in 

light of the plains spotted skunk’s high 

adaptive capacity. There are no 

geographic portions of the range in 

which the species is potentially 

endangered or threatened. 

After assessing the best available 

information, we concluded that the 

plains spotted skunk is not in danger of 

extinction or likely to become in danger 

of extinction within the foreseeable 

future throughout all of its range or in 

any significant portion of its range. 

Therefore, we find that listing the plains 

spotted skunk as an endangered species 

or threatened species under the Act is 

not warranted. A detailed discussion of 

the basis for this finding can be found 

in the plains spotted skunk species 

assessment form and other supporting 

documents on https://

www.regulations.gov under Docket No. 

FWS–R3–ES–2023–0128 (see 

ADDRESSES, above). 

Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memo on the Peer Review 

Process, we solicited independent 

scientific reviews of the information 

contained in the plains spotted skunk 

SSA report. The Service sent the SSA 

report to four independent peer 

reviewers and received two responses. 

Results of this structured peer review 

process can be found at https://

www.regulations.gov. We incorporated 

the results of these reviews, as 

appropriate, into the SSA report, which 

is the foundation for this finding. 

Sturgeon Chub and Sicklefin Chub 

Previous Federal Actions 

On August 15, 2016, we received a 

petition dated August 11, 2016, from 

WildEarth Guardians requesting that the 

sturgeon chub (Macrhybopsis gelida) 

and sicklefin chub (M. meeki) be listed 

as endangered or threatened and that 

critical habitat be designated for these 

species under the Act. On December 20, 

2017, we published a 90-day finding (82 

FR 60362) that the petition contained 

substantial information indicating that 

listing may be warranted for these 

species. We were later challenged by 

WildEarth Guardians for our failure to 

complete a 12-month finding for these 

species. Based on this litigation, we are 

now required by a September 30, 2021, 

court order to submit our 12-month 

finding for these species to the Federal 

Register by September 30, 2023. This 

document constitutes our 12-month 

finding on the August 11, 2016, petition 

to list sturgeon chub and sicklefin chub 

under the Act. 

Summary of Finding 

The sturgeon chub is a small minnow 

adapted to benthic riverine habitats 

with a slender streamlined body that 

inhabits turbid mainstem sections of the 

Missouri River and Mississippi River 

and some of their tributaries. The 

species has a widespread distribution 

and currently occupies 53 percent of its 

historical range across 12 U.S. States. 

The sicklefin chub is a small minnow 

that inhabits large, turbid rivers, 

including the mainstem Missouri and 

Mississippi Rivers. Like sturgeon chub, 

sicklefin chub have also evolved 

specific adaptations to turbid, riverine 

habitats. It is distinguished from the 

sturgeon chub by long, sickle-shaped 

pectoral fins and the absence of ridgelike projections on its scales. This 

species also has a widespread 

distribution and currently occupies 75 

percent of its historical range across 13 

U.S. States. 

Sicklefin chub primarily utilize 

mainstem river habitats, whereas 

sturgeon chub utilize both mainstem 

river and tributary habitat in both the 

Missouri and Mississippi River basins. 

Populations of both species need large 

enough areas of connected riverine 

habitat to fulfill their life-history needs 

(e.g., spawning, egg/larval drift 

distances, suitable water temperatures, 

feeding/sheltering habitat) and provide 

refugia from habitat-altering stochastic 

events (e.g., extreme flows from intense, 

sustained drought or increased 

variability in precipitation). Eggs are 

spawned in the water column during 

the summer months and develop 

(mediated by water temperature) into 

larva. Larval chubs continue to drift in 

river currents and swim vertically in the 

water column with energy provided by 

the egg yolk sac. Length of 

unfragmented reaches needed for larval 

development varies and is dependent on 

water temperature, flow velocity, and 

habitat complexity, among other 

variables. If larvae drift into a reservoir 

or still water habitat before they become 

a horizontal swimmer, it is presumed 

they settle to the bottom and experience 

high mortality. Neither species occupies 

the large stretches of reservoir habitat 

produced by dams along the Missouri 

River system. 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the sturgeon chub 

and sicklefin chub, and we evaluated all 

relevant factors under the five listing 

factors, including any regulatory 

mechanisms and conservation measures 

addressing these threats. The past 

construction of mainstem Missouri 

River dams and associated reservoirs is 

the main threat that led to the largest 

reduction in habitat for both species. In 

the future, changes in stream discharge 

from climate change is the only threat 

identified that could potentially lead to 

population-level impacts. We also 

evaluated the effects of channel 

modification, water quality, tributary 

barriers, pollutants, impingement and 

entrainment, predation, and 

hybridization. These threats are likely 

impacting both species at an individual 

level and not occurring at a scope or 

scale that would impact entire 

populations of these species. 

Both sturgeon and sicklefin chubs 

have high effective population sizes. 

Given the amount of habitat 

fragmentation that occurred historically, 

the presence of robust genetics and 

effective population estimates, despite 

the level of fragmentation, is indicative 

of highly resilient populations. Current 

occupancy and abundance information 

indicates that populations are in 

moderate to high condition. 

Furthermore, populations of both 

species currently occupy habitats with 

one or more stream fragments meeting 

or exceeding the minimum thresholds to 

meet life-history needs. Sturgeon and 

sicklefin chubs currently exhibit high 

resiliency in multiple populations 

spread throughout a large portion of 

their historical ranges, providing 

redundancy against potential 

catastrophic events. There are no 

identified threats currently affecting 

these species’ viability across their 

ranges at a population level. Thus, after 

assessing the best available information, 

we conclude that the sturgeon and 

sicklefin chub are not in danger of 

extinction throughout all of their ranges. 

When looking to the future, we have 

no indication that the construction of 

additional dams, the demolition of 

existing dams, or major differences in 

dam operations are likely to occur. 

Similarly, we have no information to 

indicate that any of the other potential 

stressors identified are going to change 

in the future at levels that would impact 

sturgeon and sicklefin chub 

populations. The primary stressor to 

these species in the future is the 


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potential for habitat loss and 

degradation from climate change. In the 

future, we project populations of both 

species to be relatively unchanged from 

their highly resilient current condition. 

These populations largely occupy 

mainstem river habitat, which is not 

likely to experience significant impacts 

from the effects of climate change on 

stream discharge. Here, we predict 

effective population size, occupancy 

and abundance, and unfragmented 

stream length to remain largely stable in 

light of potential changes to stream 

discharge. After assessing the best 

available information, we conclude that 

the sturgeon and sicklefin chub are not 

likely to become endangered within the 

foreseeable future throughout all of their 

ranges. 

We also evaluated the range of the 

sturgeon and sicklefin chub to 

determine if these species are in danger 

of extinction now or likely to become so 

within the foreseeable future in any 

portion of their ranges. For the sturgeon 

chub, we examined the following 

threats: Missouri River mainstem dams 

and reservoir operations, tributary 

barriers and habitat fragmentation, 

channel modifications, water quality, 

climate change, pollutants, 

impingement/entrainment, predation, 

and hybridization, including cumulative 

effects of the stressors. Except for 

climate change, these threats are 

ubiquitous across the range of the 

species and acting on the sturgeon chub 

more or less equally rangewide. 

Although the effect of climate change 

will impact the entire range of the 

species as well, the future impact of 

climate change on stream discharge may 

be more pronounced in the upper 

reaches of secondary tributary habitat in 

two sturgeon chub populations. These 

stream reaches are much smaller and as 

a result less buffered from future 

changes in stream discharge resulting 

from climate change than the much 

larger and more stable mainstem river 

reaches that this species inhabits. These 

are the only portions we identified as 

potentially having a difference in status 

than the rangewide status, and therefore 

worth considering further for the 

purposes of this analysis. 

The secondary tributary habitats in 

the two sturgeon chub populations 

mentioned above that may be subject to 

higher impacts from climate change 

constitute approximately 348 stream km 

(216 mi) out of 5,455 km (3,390 mi) of 

currently occupied stream km, or 

approximately 6 percent of the occupied 

range. These areas are smaller in wetted 

area and overall stream discharge than 

the mainstem river sections occupied by 

this species, and as a result may 

experience larger climate related swings 

in stream discharge which could 

negatively impact chubs living in those 

sections. These areas may be used 

opportunistically by the species when 

conditions allow, but these areas offer 

nothing ecologically unique and are not 

required by the sturgeon chub for any 

particular point of their life history. The 

mainstem river sections in these 

populations contain more sturgeon chub 

individuals and contain all of the same 

habitat features needed to meet the 

species’ needs, including sufficient 

unfragmented stream length for the 

sturgeon chub to complete their life 

cycle and maintain resilient populations 

into the future. Based on the small size 

of this portion relative to the rest of the 

range, and the lack of unique habitat 

features, we do not consider secondary 

tributary habitats to be significant for 

the purposes of this analysis. 

For the sicklefin chub, we examined 

the following threats: Missouri River 

mainstem dams and reservoir 

operations, tributary barriers and habitat 

fragmentation, channel modifications, 

water quality, climate change, 

pollutants, impingement/entrainment, 

predation, and hybridization, including 

cumulative effects. These threats are 

ubiquitous across the range of the 

species and acting on the sicklefin chub 

more or less equally rangewide. There 

are no areas with disproportionate 

impacts on sicklefin chub from these 

threats. Both sicklefin chub populations 

are currently high in resiliency and 

expected to continue to be so into the 

future despite the potential impact of 

the threats considered. Neither of the 

two populations considered as portions 

on their own meets the definition of an 

endangered or threatened species. We 

found no biologically meaningful 

portion of the sicklefin chub’s range 

where threats are impacting individuals 

differently from how they are affecting 

the species elsewhere in its range, or 

where the biological condition of the 

species differs from its condition 

elsewhere in its range such that the 

status of the species in that portion 

differs from its status in any other 

portion of the species’ range. We found 

no portion of either species’ range that 

was both significant and in danger of 

extinction now or likely to become so 

within the foreseeable future in that 

portion. Therefore, we find that these 

species are not in danger of extinction 

now or likely to become so within the 

foreseeable future in any significant 

portion of their ranges. 

After assessing the best available 

information, we concluded that 

sturgeon chub and sicklefin chub are 

not in danger of extinction or likely to 

become in danger of extinction within 

the foreseeable future throughout all of 

their ranges or in any significant portion 

of their ranges. Therefore, we find that 

listing the sturgeon chub and sicklefin 

chub as endangered species or 

threatened species under the Act is not 

warranted. A detailed discussion of the 

basis for this finding can be found in the 

sturgeon chub and sicklefin chub 

species assessment form and other 

supporting documents on https://

www.regulations.gov under Docket No. 

FWS–R6–ES–2023–0131 for the 

sturgeon chub and Docket No. FWS–R6– 

ES–2023–0130 for the sicklefin chub 

(see ADDRESSES, above). 

Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memo on the Peer Review 

Process, we solicited appropriate and 

independent scientific reviews of the 

information contained in the sturgeon 

chub and sicklefin chub SSA report. 

The Service sent the SSA report to five 

independent peer reviewers and 

received three responses. Results of this 

structured peer review process can be 

found at https://www.regulations.gov 

gov. We incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which is the foundation for these 

findings. 

Tennessee Cave Salamander 

Previous Federal Actions 

On April 20, 2010, we received a 

petition from the Center for Biological 

Diversity, Alabama Rivers Alliance, 

Clinch Coalition, Dogwood Alliance, 

Gulf Restoration Network, Tennessee 

Forests Council, and West Virginia 

Highlands Conservancy to list 404 

aquatic, riparian, and wetland species, 

including the Tennessee cave 

salamander (Gyrinophilus palleucus), as 

an endangered or threatened species 

under the Act. On September 27, 2011, 

we published a 90-day finding in the 

Federal Register (76 FR 59836) 

concluding that the petition presented 

substantial scientific or commercial 

information indicating that listing may 

be warranted. This document 

constitutes our 12-month finding on the 

April 20, 2010, petition to list the 

Tennessee cave salamander under the 

Act. 

Summary of Finding 

The Tennessee cave salamander is a 

large, obligate subterranean aquatic 

salamander that currently occurs in 89 

caves in central and southern middle 

Tennessee, northern Alabama, and 


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northwestern Georgia and one spring in 

Tennessee. Distribution of the 

Tennessee cave salamander has not 

changed significantly since its discovery 

in the mid-1940s and extirpation is only 

known from one site. Two historical 

sites were rediscovered with increased 

survey efforts in 2018. 

Little information is available on 

many aspects of the Tennessee cave 

salamander’s life history, including egg 

deposition sites, incubation, larval 

habitat and diet, and breeding behavior. 

The Tennessee cave salamander 

requires sufficient water quality and 

availability, low sediment load, suitable 

substrate and cover, and adequate food 

sources in a cave ecosystem. The extent 

of suitable habitat in occupied cave 

systems is not mapped, but the threedimensional nature of the habitat 

includes extensive areas that cannot be 

accessed and surveyed. 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the Tennessee cave 

salamander and evaluated all relevant 

factors under the five listing factors, 

including any regulatory mechanisms 

and conservation measures addressing 

these threats. The primary threats 

affecting the Tennessee cave 

salamander’s biological status include 

habitat destruction or modification (e.g., 

groundwater pollution from a variety of 

sources, sedimentation, mining and 

quarrying, groundwater extraction, and 

cave disturbance), disease, and climate 

change as well as the cumulative effects 

of the various threats on the landscape. 

Of the known threats, habitat 

destruction or modification currently is 

the primary threat rangewide to the 

species’ current and future viability. 

Impacts to the species’ habitat 

rangewide are caused by groundwater 

pollution from contaminants, and 

sedimentation associated with 

urbanization, agriculture, and 

silviculture. Impacts to individuals and 

populations may occur as a result of 

mining and quarrying, human visitation, 

and disease. The best available 

information does not indicate that the 

influence of climate change alone on the 

species’ current condition is significant, 

but the effects of climate change may act 

synergistically with other threats to 

exacerbate the effects of urbanization, 

drought, and water withdrawal, 

particularly in the future. 

Although the Tennessee cave 

salamander is a cryptic species that 

occurs in relatively inaccessible 

subterranean habitat, the best available 

information indicates that the species is 

present in all 12 historically occupied 

AUs. The Tennessee cave salamander 

currently exhibits high resiliency in two 

AUs and moderate resiliency in eight 

AUs. The two AUs in high resiliency 

make up the stronghold of the species’ 

range. The two low resiliency AUs 

occur on the periphery of the species’ 

range, and each is characterized by 

relatively few sites with species 

occurrence. Approximately 33 percent 

of known sites and over 50 percent of 

sites in the two AUs that make up the 

stronghold of the range occur on 

protected lands that confer some degree 

of protection to the species from threats 

caused by land use. Representation and 

redundancy have not declined from 

historical levels and are sufficient to 

support current Tennessee cave 

salamander viability. Overall, no threat 

is acting to an extent or severity such 

that the Tennessee cave salamander is at 

risk of extinction throughout its range. 

The Tennessee cave salamander is 

expected to remain extant in all 12 AUs 

in all future scenarios. Our future 

condition analysis projected slight 

declines or declines in resiliency in one 

to nine AUs depending on the scenario 

and time step. There are minor 

projected increases in some threats that 

may affect the availability of suitable 

habitat across the species’ range. We 

expect the loss of forest cover to have 

a negative impact on the habitat 

conditions for the species, but there is 

limited information quantitatively 

linking changes in forest cover surface 

condition and cave environments in the 

species’ range. The species’ response to 

projected changes also has not been 

observed or quantified. 

In the future, the impacts under 

scenario 1 (status quo minimum) 

projected very minor changes to 

resiliency with only a slight decrease in 

one unit in 2040 and three units in 

2060. Under scenario 2 (status quo 

maximum), with incorporation of a 

greater magnitude of forest loss, nine 

AUs are projected to exhibit no change 

in resiliency while only two units are 

projected to decrease by 2060 (only one 

unit by 2040). Under scenario 3 

(increased impacts scenario), the 

magnitude of impact is greatest, with 5 

of 12 AUs projected to exhibit decreased 

resiliency in both 2040 and 2060. 

Nevertheless, even in the greatest 

impact scenario, 6 of 12 AUs are 

projected to exhibit moderate or high 

resiliency. The resiliency of the two 

AUs that make up the stronghold of the 

range is not projected to change under 

any scenario and time step. No analysis 

unit-level extirpations are projected. 

Although representation and 

redundancy are projected to decline as 

a function of resiliency decreases under 

some scenarios and time steps, the 

species maintains sufficient adaptive 

capacity and ability to withstand 

catastrophic events to support future 

viability. 

Although threats are similar 

throughout the range of the species, 

some local sites may be more affected by 

specific threats. For example, the 

species’ response to threats is more 

pronounced in the Lower Tennessee 

and Lower Elk AUs. These AUs 

currently exhibit low resiliency driven 

primarily by low abundance, a lower 

degree of forest, and a higher degree of 

agricultural land use surrounding the 

low number of known sites in each AU 

(three sites in the Lower Tennessee and 

one site in the Lower Elk). Given the 

species’ condition within the Lower 

Tennessee and Lower Elk AUs, we have 

identified the two units on the 

periphery of the species’ range as areas 

that may be in danger of extinction now 

or within the foreseeable future due to 

the low current resiliency. Both AUs are 

projected to decline in resiliency in the 

future. 

We then proceeded to the question of 

significance, asking whether the Lower 

Tennessee or Lower Elk AU meets the 

current understanding of significance. 

Although the Lower Tennessee and 

Lower Elk AUs contribute to the overall 

species-level representation and 

redundancy, the two AUs do not 

contain any high quality or high value 

habitat or any habitat or resources 

unique to the area and necessary to the 

Tennessee cave salamander’s life 

history. In addition, the AUs encompass 

a low number of known sites with 

species’ occurrences and do not make 

up a large geographic area of the 

species’ range or contain a high 

proportion of its habitat or populations. 

Accordingly, we do not find the Lower 

Tennessee or Lower Elk AU, singly or 

collectively, to be a significant portion 

of the range. 

After assessing the best available 

information, we conclude that the 

Tennessee cave salamander is not in 

danger of extinction or likely to become 

in danger of extinction within the 

foreseeable future throughout all of its 

range or in any significant portion of its 

range. Therefore, we find that listing the 

Tennessee cave salamander as an 

endangered species or threatened 

species under the Act is not warranted. 

A detailed discussion of the basis for 

this finding can be found in the 

Tennessee cave salamander species 

assessment form and other supporting 

documents on https://

www.regulations.gov under Docket No. 

FWS–R4–ES–2023–0133 (see 

ADDRESSES, above). 


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Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memorandum on the Peer 

Review Process, we solicited 

independent scientific reviews of the 

information contained in the Tennessee 

cave salamander SSA report. The 

Service sent the SSA report to five 

independent peer reviewers and 

received four responses. Results of this 

structured peer review process can be 

found at https://www.regulations.gov. 

We incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which is the foundation for this 

finding. 

Yazoo Crayfish 

Previous Federal Actions 

The Yazoo crayfish (Faxonius 

hartfieldi, formerly Orconectes 

hartfieldi) was included in a listing 

petition from the Center for Biological 

Diversity et al. (CBD 2010, pp. 792–793) 

in April 2010. The petition requested 

that the Service list 404 aquatic, 

riparian, and wetland species as 

endangered or threatened under the Act. 

In 2011, the Service found that this 

petition presented substantial scientific 

or commercial information indicating 

that listing may be warranted for the 

Yazoo crayfish (76 FR 59836; September 

27, 2011). This document constitutes 

our 12-month finding on the April 2010 

petition to list the Yazoo crayfish under 

the Act. 

Summary of Finding 

The Yazoo crayfish is a streamdwelling species distributed among 

scattered locations in the Yazoo and Big 

Black River drainages in Mississippi. 

The species is small growing to 50 to 70 

mm (2 to 3 in) in total length. 

Historically, the Yazoo crayfish was 

known from the Yazoo to the Big Black 

River drainage in Mississippi. The 

Yazoo crayfish currently occupies a 

wide range of stream sizes from small 

headwater streams such as the first 

order Little Mouse Creek (watershed 

area: 11 square kilometers (km2) (4.25 

square miles (m2))) to large streams such 

as Fourteen mile Creek (watershed area: 

644 km2 (249 m2)). Occupied streams 

have moderate gradients and are located 

in the Lower and Upper Gulf Coastal 

Plain ecoregions. 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the Yazoo crayfish 

and evaluated all relevant factors under 

the five listing factors, including any 

regulatory mechanisms and 

conservation measures addressing these 

threats. The primary threat identified for 

the Yazoo crayfish is habitat 

fragmentation resulting from a number 

of factors such as stream channelization, 

sedimentation, road crossings, 

impoundments, and development. 

Other primary stressors affecting the 

species’ biological status include 

regulated river flows, pollution, and 

climate change. Sedimentation in 

streams is often a result of within 

channel erosion of banks, head cutting, 

and stream incisement, which are 

usually the result of past land cover and 

land use practices (e.g., channelization). 

Increased sedimentation from a variety 

of sources (e.g., timber harvest that does 

not use best management practices, row 

crop agriculture, and urbanization) is 

detrimental to stream habitats for a 

variety of reasons. 

Currently, the Yazoo crayfish 

occupies 12 analytical units across 20 

hydrologic unit code (HUC)–12 

watersheds in four HUC 8 watersheds 

and three level IV ecoregions. Five 

analytical units are considered to be 

high resiliency, three to be moderate 

resiliency, and four to be low resiliency. 

The highest resiliency analytical units 

are those with a higher number of 

occupied watersheds, lower 

channelization, lower fragmentation, 

and higher forest cover. In general, 

current land use practices do not appear 

to have an appreciable negative impact 

on the resiliency, redundancy, and 

representation. Moreover, habitat 

conditions for the species have been 

improving over the past 10–20 years 

(reduction in agriculture, increase in 

forested habitat within occupied 

watersheds, developed landcover has 

decreased). Lingering effects of prior 

land uses and management practices 

continue to impact the species, but there 

is evidence that streams are recovering 

from these land uses and habitat may be 

improving. Although threats are present 

on the landscape, the Yazoo crayfish has 

multiple moderate and high resilient 

populations distributed across the 

landscape, providing the species with 

adequate redundancy and 

representation. Therefore, the threats 

appear to have low imminence and 

magnitude such that they currently are 

not significantly affecting the species’ 

viability. The SSA report describes 

some of the uncertainties in the species’ 

occurrence, populations, and response 

to threats; however, considering the 

available data, the risk of extinction is 

low due to the distribution of multiple 

high and moderate resiliency units 

across the species’ range. Thus, after 

assessing the best available information, 

we conclude that the Yazoo crayfish is 

not in danger of extinction throughout 

all of its range. 

Land use patterns are projected to 

continue over the next 30 years. Human 

population density is low in most of the 

range, so impacts related to urbanization 

and development are generally low and 

show minimal change under future 

scenarios B1 and A2 in 2040. Future 

scenarios in 2060 demonstrate an 

increase of urbanization in some 

analytical units, resulting in a decrease 

in resiliency of four analytical units 

under scenario B1 and five analytical 

units under scenario A2; however, 

seven analytical units remain in 

moderate or high condition in scenario 

B1, while eight units remain in 

moderate or high condition in scenario 

A2. Although change is predicted to 

occur due to threats on the landscape, 

our analysis indicates that the 

magnitude of change under both 

scenarios and timesteps does not 

indicate a significant risk to future 

viability of the Yazoo crayfish. The 

species is expected to experience slight 

reductions in resiliency by 2060, but 

moderate and high resiliency 

populations are expected to remain 

across the species’ range. In addition, 

recent increases in sampling efforts have 

resulted in significant expansion of the 

species’ current range, and it is 

predicted that future increases in 

sampling efforts will produce similar 

results. After assessing the best available 

information, we conclude that the 

Yazoo crayfish is not likely to become 

endangered within the foreseeable 

future throughout all of its range. 

We evaluated the range of the Yazoo 

crayfish to determine if it is in danger 

of extinction now or likely to become so 

within the foreseeable future in any 

portion of its range. The species is a 

range-limited, stream-dwelling species 

that occurs within a very small area 

distributed among scattered locations in 

the Yazoo and Big Black River drainages 

of Mississippi. The range of a species 

theoretically can be divided into 

portions in an infinite number of ways. 

We focused our analysis on portions of 

the species’ range that may meet the 

Act’s definition of an ‘‘endangered 

species’’ or a ‘‘threatened species.’’ We 

considered whether the threats or their 

effects on the Yazoo crayfish are greater 

in any biologically meaningful portion 

of the species’ range than in other 

portions such that the species is in 

danger of extinction now or likely to 

become so within the foreseeable future 

in that portion. Based on the best 

available science, these factors are not 

concentrated within a specific portion 


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of the species’ range but spread 

throughout its range. 

Currently, there are moderate and 

high resiliency populations occurring in 

each ecoregion. In Northern Hilly Gulf 

Coastal Plain, there are two moderate 

resiliency populations and one low 

resiliency population. In Southern Hilly 

Gulf Coastal Plain, there are two low 

resiliency populations and one high 

resiliency population. In Loess Plain, 

there are two moderate resiliency 

populations and four high resiliency 

populations. We project in the future at 

least one moderate and/or high 

resiliency population occurring in each 

ecoregion: In Northern Hilly Gulf 

Coastal Plain, there are projected to be 

two low resiliency populations and one 

moderate resiliency population; in 

Southern Hilly Gulf Coastal Plain, there 

are projected to be two very low 

resiliency populations and one 

moderate resiliency population; and in 

Loess Plain, there are projected to be 

three moderate resiliency populations 

and three high resiliency populations. 

The current and future condition 

analyses of the Yazoo crayfish indicate 

sufficient resiliency, representation, and 

redundancy in each ecoregion. As a 

result, there are no portions of the 

species’ range where the species has a 

different biological status from its 

rangewide biological status. Therefore, 

we conclude that there are no portions 

of the species’ range that warrant further 

consideration, and the species is not in 

danger of extinction or likely to become 

so within the foreseeable future in any 

significant portion of its range. 

After assessing the best available 

information, we conclude that the 

Yazoo crayfish is not in danger of 

extinction or likely to become in danger 

of extinction within the foreseeable 

future throughout all of its range or in 

any significant portion of its range. 

Therefore, we find that listing the Yazoo 

crayfish as an ‘‘endangered species’’ or 

‘‘threatened species’’ under the Act is 

not warranted. A detailed discussion of 

the basis for this finding can be found 

in the Yazoo crayfish species 

assessment form and other supporting 

documents on https://

www.regulations.gov under Docket No. 

FWS–R4–ES–2023–0134 (see 

ADDRESSES, above). 

Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memo on the Peer Review 

Process, we solicited independent 

scientific reviews of the information 

contained in the Yazoo crayfish SSA 

report. The Service sent the SSA report 

to five independent peer reviewers and 

received two responses. Results of this 

structured peer review process can be 

found at https://www.regulations.gov. 

We incorporated the results of these 

reviews, as appropriate, in the SSA 

report, which is the foundation for this 

finding. 

Southern Sea Otter 

Previous Federal Actions 

On January 14, 1977, we published a 

final rule (42 FR 2965) to list the 

southern sea otter as a threatened 

species. On March 10, 2021, we 

received a November 2020 petition from 

the Pacific Legal Foundation, counsel 

for California Sea Urchin Commission 

and Commercial Fishermen of Santa 

Barbara, requesting that the southern sea 

otter (Enhydra lutris nereis) be removed 

from the Federal List of Endangered and 

Threatened Wildlife (i.e., ‘‘delisted’’) 

because the species does not meet the 

Act’s definition of an endangered or a 

threatened species. On August 23, 2022, 

we published a 90-day finding (87 FR 

51635) that the petition presented 

substantial scientific or commercial 

information indicating that delisting the 

southern sea otter may be warranted. 

This document constitutes our 12- 

month finding on the March 10, 2021, 

petition to delist southern sea otter. 

Summary of Finding 

The southern sea otter historically 

ranged from Oregon in the United States 

(which is thought to have been a 

transition zone between the northern 

and southern subspecies), to the species’ 

southern range terminus near Punta 

Abreojos, Baja California, Mexico. The 

maritime fur trade of the 18th and 19th 

centuries caused the near-extinction of 

sea otters throughout their North Pacific 

range. All present-day southern sea 

otters descended from a small remnant 

population that survived the fur trade 

near Bixby Creek in Monterey County, 

California. Currently, the subspecies 

occurs only in portions of California: 

along roughly 500 km (310 mi) of the 

mainland coastline from San Mateo 

County to Santa Barbara County, and in 

the waters surrounding San Nicolas 

Island, Ventura County, although 

occasionally individuals are 

documented in other areas. 

Southern sea otters occupy a variety 

of coastal marine habitats, including 

rocky exposed coastline, sandy 

embayments, and estuaries. Sea otter 

habitat in California is typically defined 

by the 40 m (131 ft) or 60 m (197 ft) 

depth contour. Depending on local 

bathymetry, most sea otters in California 

reside within 2 km (1.2 mi) of shore. At 

the individual level, sea otters need 

benthic invertebrate prey, coastal 

marine waters less than 40 m (131 ft) in 

depth, and sheltered resting habitat 

consisting of canopy-forming kelp, 

shallow protected waters (e.g., 

estuaries), or haul out areas. At the 

population level, sea otters need 

sufficient abundance and adequate rates 

of survival, recruitment, and dispersal 

to rebound from disturbance and persist 

at the population or metapopulation 

scale. At the species level, sea otters 

need adequate redundancy to spread the 

risk of large-scale, high-impact (i.e., 

catastrophic) events among multiple 

populations or areas; they also need 

adequate genetic and environmental 

diversity to be able to adapt to changing 

environmental conditions. 

For additional information on the 

physical characteristics, genetics, 

taxonomy, habitat, life history, and 

historical and current distribution, see 

chapter 3 of the SSA report (Service 

2023, pp. 12–26. For additional 

information on population and species 

needs, see chapter 3 of the SSA report 

(Service 2023, pp. 22–23). 

We have carefully assessed the best 

scientific and commercial information 

available regarding the past, present, 

and future threats to the southern sea 

otter, and we evaluated all relevant 

factors under the five listing factors 

including any regulatory mechanisms 

and conservation measures addressing 

these threats. We examined the 

following threats: curtailment of its 

range; harmful algal or cyanobacterial 

bloom intoxication; shark bite mortality; 

end-lactation syndrome; cardiac disease; 

protozoal infection; acanthocephalan 

peritonitis; infections (other); natural 

causes (other); human causes (shootings, 

boat strikes, and entanglements); human 

causes (oil spills); loss of genetic 

diversity; and climate change, including 

synergistic and cumulative effects. Of 

these threats, the southern sea otter is 

currently most imperiled by high shark 

bite mortality, curtailment of its range, 

and changes related to climate. 

Due in part to listing under the Act in 

1977 and ongoing conservation efforts, 

the range-wide population index for 

southern sea otters has increased to 

2,962 as of 2019 (the most recent year 

a full census was completed); the 

mainland range has increased by 

approximately 210 km (130 mi) to 

encompass roughly 500 km (310 mi) of 

linear coastline; and a translocated 

subpopulation has taken hold at San 

Nicolas Island. Although current 

numbers and range remain restricted, 

the southern sea otter is likely to sustain 

populations in the wild in the near 

term. The current abundance of 2,962 


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otters is far below estimated carrying 

capacity of California, but above the 

roughly 50 animals that remained in 

1914. Seven of 29+ subpopulations are 

currently extant. However, the results of 

population projections based on three 

plausible future scenarios indicated that 

meaningful improvements in resiliency, 

redundancy, and representation are 

unlikely to occur within the foreseeable 

future. 

As noted above, the southern sea otter 

remains most imperiled by high shark 

bite mortality, the curtailment of its 

range, and climate change and 

associated effects. Based on our 

projections of future conditions for the 

species, and the existing and increased 

threats in the future on the species from 

shark bite mortality, range curtailment, 

and impacts of climate change, the 

species will experience continued and 

increasing impacts on its abundance 

and connectivity between populations 

that will most likely cause the species 

to be increasingly less able to support 

itself into the future. Additionally, 

existing regulatory mechanisms and 

conservation measures do not appear to 

be sufficient to protect the southern sea 

otter from emerging or intensifying 

threats. 

After assessing the best available 

information, we concluded that 

southern sea otter is likely to become in 

danger of extinction within the 

foreseeable future throughout all of its 

range. Therefore, we find that delisting 

the southern sea otter under the Act is 

not warranted. A detailed discussion of 

the basis for this finding can be found 

in the southern sea otter species 

assessment form and other supporting 

documents on https://

www.regulations.gov under Docket No. 

FWS–R8–ES–2023–0132 (see 

ADDRESSES, above). 

Peer Review 

In accordance with our July 1, 1994, 

peer review policy (59 FR 34270; July 1, 

1994) and the Service’s August 22, 2016, 

Director’s Memo on the Peer Review 

Process, we solicited independent 

scientific reviews of the information 

contained in the southern sea otter SSA 

report. The Service sent the SSA report 

to three independent peer reviewers and 

three partner reviewers. We received 

responses back from one peer reviewer 

and one partner reviewer. Results of this 

structured peer review process can be 

found at https://www.regulations.gov. 

We incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which is the foundation for this 

finding. 

New Information 

We request that you submit any new 

information concerning the taxonomy, 

biology, ecology, status of, or stressors 

to the Cascades frog, plains spotted 

skunk, sicklefin chub, southern sea 

otter, sturgeon chub, Tennessee cave 

salamander, or Yazoo crayfish to the 

appropriate person, as specified under 

FOR FURTHER INFORMATION CONTACT, 

whenever it becomes available. New 

information will help us monitor these 

species and make appropriate decisions 

about their conservation and status. We 

encourage local agencies and 

stakeholders to continue cooperative 

monitoring and conservation efforts. 

References Cited 

A list of the references cited in each 

petition finding is available in the 

relevant species assessment form, which 

is available on the internet at https://

www.regulations.gov in the appropriate 

docket (see ADDRESSES, above) and upon 

request from the appropriate person (see 

FOR FURTHER INFORMATION CONTACT, 

above). 

Authors 

The primary authors of this document 

are the staff members of the Species 

Assessment Team, Ecological Services 

Program. 

Authority 

The authority for this action is section 

4 of the Endangered Species Act of 

1973, as amended (16 U.S.C. 1531 et 

seq.). 

Martha Williams, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2023–20296 Filed 9–19–23; 8:45 am] 

BILLING CODE 4333–15–P 


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