Proposed Rule2024-23929
Endangered and Threatened Wildlife and Plants; Removing Chipola Slabshell and Fat Threeridge From the Federal List of Endangered and Threatened Wildlife
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
October 29, 2024
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), propose to remove the Chipola slabshell (Elliptio chipolaensis) and fat threeridge (Amblema neislerii), both freshwater mussels, from the Federal List of Endangered and Threatened Wildlife due to recovery. These species occur in the Apalachicola-Chattahoochee-Flint River Basin of Alabama, Georgia, and Florida. Our review of the best available scientific and commercial data indicates that the threats to the Chipola slabshell and fat threeridge have been eliminated or reduced to the point that both species have recovered and no longer meet the definition of an endangered or threatened species under the Endangered Species Act of 1973, as amended (Act). Accordingly, we propose to delist the Chipola slabshell and the fat threeridge. If we finalize this rule as proposed, the prohibitions and conservation measures provided by the Act, particularly through sections 4 and 7 for the Chipola slabshell and sections 7 and 9 for the fat threeridge, would no longer apply to these species. This proposed rule also serves as the completed status review initiated under section 4(c)(2) of the Act.
Full Text
<html>
<head>
<title>Federal Register, Volume 89 Issue 209 (Tuesday, October 29, 2024)</title>
</head>
<body><pre>
[Federal Register Volume 89, Number 209 (Tuesday, October 29, 2024)]
[Proposed Rules]
[Pages 85909-85934]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-23929]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R4-ES-2024-0051; FXES1113090FEDR-245-FF09E22000]
RIN 1018-BF55
Endangered and Threatened Wildlife and Plants; Removing Chipola
Slabshell and Fat Threeridge From the Federal List of Endangered and
Threatened Wildlife
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
remove the Chipola slabshell (Elliptio chipolaensis) and fat threeridge
(Amblema neislerii), both freshwater mussels, from the Federal List of
Endangered and Threatened Wildlife due to recovery. These species occur
in the Apalachicola-Chattahoochee-Flint River Basin of Alabama,
Georgia, and Florida. Our review of the best available scientific and
commercial data indicates that the threats to the Chipola slabshell and
fat threeridge have been eliminated or reduced to the point that both
species have recovered and no longer meet the definition of an
endangered or threatened species under the Endangered Species Act of
1973, as amended (Act). Accordingly, we propose to delist the Chipola
slabshell and the fat threeridge. If we finalize this rule as proposed,
the prohibitions and conservation measures provided by the Act,
particularly through sections 4 and 7 for the Chipola slabshell and
sections 7 and 9 for the fat threeridge, would no longer apply to these
species. This proposed rule also serves as the completed status review
initiated under section 4(c)(2) of the Act.
DATES: We will accept comments received or postmarked on or before
December 30, 2024. We must receive requests for public hearings, in
writing, at the address shown in FOR FURTHER INFORMATION CONTACT by
December 13, 2024.
ADDRESSES:
Written comments: You may submit comments by one of the following
methods:
(1) Electronically: Go to the Federal eRulemaking Portal: <a href="https://www.regulations.gov">https://www.regulations.gov</a>. In the Search box, enter FWS-R4-ES-2024-0051,
which is the docket number for this rulemaking. Then, click on the
Search button. On the resulting page, in the Search panel on
[[Page 85910]]
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 must be received by 11:59 p.m.
Eastern Time on the closing date listed in the DATES section.
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R4-ES-2024-0051, U.S. Fish and Wildlife Service,
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on <a href="https://www.regulations.gov">https://www.regulations.gov</a>. This
generally means that we will post any personal information you provide
us (see Information Requested, below, for more information).
Availability of supporting materials: This proposed rule and
supporting documents, including the recovery plans, 5-year review, and
species status assessment (SSA) reports, are available at <a href="https://ecos.fws.gov/ecp/">https://ecos.fws.gov/ecp/</a> and at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No.
FWS-R4-ES-2024-0051.
FOR FURTHER INFORMATION CONTACT: Gian Basili, Deputy State Supervisor,
Florida Ecological Services Office, 7915 Baymeadows Way, Suite 200,
Jacksonville, FL 32256-7517; telephone 904-731-3079; email
<a href="/cdn-cgi/l/email-protection#600709010e0612010e030f3f020113090c09200617134e070f16"><span class="__cf_email__" data-cfemail="284f4149464e5a49464b47774a495b414441684e5f5b064f475e">[email protected]</span></a>. Individuals in the United States who are
deaf, deafblind, hard of hearing, or have a speech disability may dial
711 (TTY, TDD, or TeleBraille) to access telecommunications relay
services. Individuals outside the United States should use the relay
services offered within their country to make international calls to
the point-of-contact in the United States. Please see Docket No. FWS-
R4-ES-2024-0051 on <a href="https://www.regulations.gov">https://www.regulations.gov</a> for a document that
summarizes this proposed rule.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species warrants
delisting if it no longer 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
in the foreseeable future throughout all or a significant portion of
its range). The Chipola slabshell is listed as a threatened species and
the fat threeridge is listed as an endangered species, and we are
proposing to delist them. We have determined the Chipola slabshell and
fat threeridge do not meet the Act's definition of an endangered or
threatened species. Delisting a species 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. This rule proposes the removal of the
Chipola slabshell and fat threeridge from the List of Endangered and
Threatened Wildlife based on their recovery; if we finalize this rule
as proposed, the prohibitions and conservation measures provided by the
Act, particularly through sections 4 and 7 for the Chipola slabshell
and sections 7 and 9 for the fat threeridge, would no longer apply to
these 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. The determination to delist a species must be
based on an analysis of the same factors.
Under the Act, we must review the status of all listed species at
least once every five years. We must delist a species if we determine,
on the basis of the best available scientific and commercial data, that
the species is neither a threatened species nor an endangered species.
Our regulations at 50 CFR 424.11 identify four reasons why we might
determine a species shall be delisted: (1) The species is extinct; (2)
the species has recovered to the point at which it no longer meets the
definition of an endangered species or a threatened species; (3) new
information that has become available since the original listing
decision shows the listed entity does not meet the definition of an
endangered species or a threatened species; or (4) new information that
has become available since the original listing decision shows the
listed entity does not meet the definition of a species. Here, we have
determined that the Chipola slabshell and fat threeridge have recovered
to the point at which they no longer meet the definition of an
endangered species or a threatened species; therefore, we are proposing
to delist them.
Information Requested
We intend that any final action resulting from this proposal 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 concerned governmental agencies, Native
American Tribes, the scientific community, industry, or any other
interested parties concerning this proposed rule.
We particularly seek comments concerning:
(1) Reasons we should or should not remove Chipola slabshell or fat
threeridge from the List of Endangered and Threatened Wildlife.
(2) Relevant data concerning any threats (or lack thereof) to the
Chipola slabshell or fat threeridge, particularly any data on the
possible effects of climate change as it relates to habitat, as well as
the extent of State protection and management that would be provided to
these mussels as delisted species;
(3) Current or planned activities within the geographic range of
Chipola slabshell and fat threeridge that may have adverse or
beneficial impacts on these species; and
(4) Considerations for post-delisting monitoring, including
monitoring protocols and length of time monitoring is needed, as well
as triggers for reevaluation.
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 actions 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 species or a threatened species must be made solely on the
basis of the best scientific and commercial data available.
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via <a href="https://www.regulations.gov">https://www.regulations.gov</a>, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so.
[[Page 85911]]
We will post all hardcopy submissions on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Our final determinations 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. For
example, based on the new information we receive (and if relevant, any
comments on that new information), we may conclude that Chipola
slabshell should remain listed as a threatened species, or we may
conclude that Chipola slabshell should be reclassified from a
threatened species to an endangered species. We may conclude that the
fat threeridge should remain listed as an endangered species, or we may
conclude that the fat threeridge should be reclassified from an
endangered species to a threatened species. 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 these virtual public
hearings is consistent with our regulations at 50 CFR 424.16(c)(3).
Peer Review
Species status assessment (SSA) teams prepared separate SSA reports
for the Chipola slabshell and fat threeridge. The SSA teams were
composed of Service biologists and staff from Texas A&M Natural
Resource Institute, who consulted with subject area experts for both
species. Each SSA report represents a compilation of the best
scientific and commercial data available concerning the status of these
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 our August 22,
2016, memorandum updating and clarifying the role of peer review of
listing and recovery actions under the Act, we solicited independent
scientific reviews of the information contained in each of the SSA
reports. We sent the Chipola slabshell SSA report to three independent
peer reviewers and received two responses. We sent the fat threeridge
SSA report to four independent peer reviewers and received two
responses. Results of these structured peer review processes can be
found at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. In preparing this proposed rule,
we incorporated the results of these reviews, as appropriate, into the
final SSA report for each species, which are the foundation for this
proposed rule.
Summary of Peer Reviewer Comments
As discussed in Peer Review above, we received comments from two
peer reviewers on each of the draft SSA reports. We reviewed all
comments we received from the peer reviewers for substantive issues and
new information regarding the information contained in the SSA reports.
The peer reviewers generally concurred with our methods and
conclusions, and provided additional information, clarifications, and
suggestions, including clarifications in terminology and discussions of
survey information related to detection versus no detection, and other
editorial suggestions. Otherwise, no substantive changes to our
analysis and conclusions within either of the SSA reports were deemed
necessary, and peer reviewer comments are addressed in versions 1.0 of
each SSA report (Service 2020, entire; Service 2021, entire).
Previous Federal Actions
On March 16, 1998, the Chipola slabshell was listed as a threatened
species (63 FR 12664) and the fat threeridge as an endangered species
(63 FR 12664) under the Act. On October 1, 2003, we completed a
recovery plan for both species (68 FR 56647). A 5-year review of 37
Southeastern species, including Chipola slabshell and fat threeridge,
was completed on September 27, 2006 (71 FR 56545). Critical habitat was
designated for the Chipola slabshell in the Chipola River main stem and
seven tributaries comprising a stream length of approximately 228 km
(142 mi) (72 FR 64286; November 15, 2007). Critical habitat was
designated for the fat threeridge in the lower Flint River system (397
km (247 mi)), the Apalachicola River system (161 km (100 mi)), and the
Chipola River system (228 km (142 mi)) (72 FR 64286; November 15,
2007). We published notices of initiation of periodic status reviews
for both species as required under section 4(c)(2) of the Act in 2018
(83 FR 38320, August 6, 2018); this proposed rule serves as completion
of those status reviews. Recovery plan revisions were completed for
both species on August 6, 2019 (84 FR 38284). The referenced documents
and additional details can be found using our Environmental
Conservation Online System (ECOS): <a href="https://ecos.fws.gov/">https://ecos.fws.gov/</a>.
Background
Species Information
Both the Chipola slabshell and fat threeridge are members of the
family Unionidae, a large group of freshwater mussels represented by
298 species in North America. Both species are endemic to the
Apalachicola-Chattahoochee-Flint River (ACF) River Basin of Alabama,
Georgia, and Florida. The ACF River Basin extends approximately 620
kilometers (km) (385 miles (mi)) and spans 50 counties in Georgia, 8 in
Florida, and 10 in Alabama (see figure 1, below). For more details
about the ACF River Basin, refer to the SSA reports (Service 2020, pp.
12-15; Service 2021, pp. 26-50).
The Chipola slabshell occurs in the mainstem of the Chipola River
and several large tributaries. The fat threeridge occurs in the
mainstems of the Flint River, Chipola River, and Apalachicola River.
Neither species has known occurrences within the Chattahoochee River
basin.
[[Page 85912]]
[GRAPHIC] [TIFF OMITTED] TP29OC24.000
General Mussel Biology
Freshwater mussels, including Chipola slabshell and fat threeridge,
have a complex reproduction process involving parasitic larvae, called
glochidia, that are wholly dependent on host fish. Mussels release
sperm into the water column, which is taken in by the female, wherein
fertilization and development of glochidia occurs in a restricted
portion of the gills, called the brood pouch or marsupium. When mature,
the glochidia are released to the water column to attach on the gills,
head, or fins of fishes. Glochidia die if they fail to attach to a host
fish, attach to an incompatible fish species, or attach to the wrong
location on a host fish (Neves 1991, p. 254; Bogan 1993, p. 599). Once
attached to the host, glochidia draw nutrients from the fish's tissue
as they develop (Arey 1932, pp. 214-215). Time to development, from
attachment of glochidia to maturation,
[[Page 85913]]
ranges from just over 1 week to 6 weeks or more (Parmalee and Bogan
1998, p. 8).
Depending on the species, mussels are either short-term or long-
term brooders. In short-term brooders, such as Chipola slabshell and
fat threeridge, fertilization occurs in the spring or summer and
glochidia are released shortly after they are fully developed. In long-
term brooders, fertilization occurs in late summer or fall, and
developed glochidia are held over winter and released in the following
spring or summer (Haag 2012, pp. 39-40). Mature glochidia drop off
their hosts and, if they settle in suitable habitat on the stream
bottom, continue the remainder of their existence as free-living
mussels. Newly released glochidia are juveniles that are reproductively
immature but otherwise resemble adults, with both halves (valves) of
the shell developed and poised for growth.
Freshwater mussels are relatively sedentary and, under their own
power, capable of moving only short horizontal distances, typically up
to a few yards or less in a year (Haag 2012, pp. 34-35). Given mussels'
limited mobility, host fish are their primary mode of dispersal, and
the hosts are essential for maintaining population connectivity. Host
specificity varies, with some mussel species being compatible with a
few fish species while others can transform from glochidia to juveniles
on several fish species.
Chipola Slabshell
A thorough review of the taxonomy, life history, and ecology of the
Chipola slabshell is presented in chapter 1 of the SSA report (Service
2020, pp. 3-24).
The Chipola slabshell is a freshwater mussel that does not exhibit
sexual dimorphism in shell characters (Service 2020, p. 4). The species
can attain a length of 85 millimeters (mm) (3.35 inches (in)), but
typical length is between 47 to 76 mm (1.85 to 2.99 in). The Chipola
slabshell has a chestnut colored periostracum (outer shell) with 1 to 4
dark annuli (growth) bands (Service 2020, p. 4). Within its range,
Chipola slabshell is the only species with light and dark bands on
periostracum and with salmon-colored nacre (inner layer of shell)
inside the shell. The umbos (shell protrusions near the hinge) are
prominent, well above the hingeline, thus inside the umbo cavity is
deep.
Based on the size, shell characteristics, and traits from similar
species in the genus Elliptio, the Chipola slabshell is thought to
reach sexual maturity within 3-5 years and has an average lifespan of
15-20 years (Service 2020, p. 8). The Chipola slabshell is a short-term
brooder (tachytictic), meaning immature mussels (i.e., glochidia) are
carried in the female's gills for a short time following spawning and
released that same season. Females are gravid from early June to early
July. The Chipola slabshell is a host-fish specialist, requiring a
Centrarchid (i.e., sunfish) host.
Currently, the Chipola slabshell is widespread within its range and
common at some localities. A lack of consistent survey methods across
observers and through time limits the discussion of abundance trends
for Chipola slabshell, however historical data indicate approximately
32 records whereas current records (from 2005 onward) indicate
approximately 138 (Service 2020, p. 62). The species' distribution is
primarily continuous in one river system, including the Chipola River
and its tributaries. The species inhabits silty sand substrates of
large creeks and the main channel of the Chipola River, in slow to
moderate current. Chipola slabshell appears to be more tolerant of soft
sediments than other mussel species in the ACF River Basin. It co-
occurs with more silt-tolerant species in stream bank habitats with
slower currents, thus it has more available habitat than mid-channel-
dwelling species (Service 2020, p. 15).
Fat Threeridge
A thorough review of the taxonomy, life history, and ecology of the
fat threeridge mussel is presented in chapter 2 of the SSA report
(Service 2021, pp. 14-25).
The fat threeridge is an almost square, inflated, solid, and heavy
shelled freshwater mussel that typically reaches up to 102 mm (4 in) in
length. Older, larger individuals are quite inflated, where their width
approximates their height. The dark brown to black shell is strongly
sculptured with seven to eight prominent horizontal parallel ridges.
The prominent, parallel ridges and inflated shell (older specimens,
especially) distinguish this species from other mussels within its
range (Service 2021, p. 15).
The glochidia of fat threeridge, like most freshwater mussels, are
obligate parasites on fish, and must attach to a host to transform into
juvenile mussels; this parasitism serves as the primary dispersal
mechanism for this relatively immobile group of organisms. To
facilitate attachment, fat threeridge hookless glochidia are broadcast
in a web-like mass that expands and wraps around a host. This method
often is seen in host generalists because passive entanglement is
nonselective. Reproductive studies confirm that fat threeridge is a
host generalist, completing transformation on 23 species of fishes
(Service 2021, p. 17). The fat threeridge is a short-term summer
brooder. Females appear to be gravid when water temperatures reach 23.9
degrees Celsius ([deg]C) (75 degrees Fahrenheit ([deg]F)), usually in
late May and June.
Because freshwater mussels are relatively long-lived and have
limited mobility, habitat stability is a requirement shared by all
unionids. Fat threeridge appears to be sensitive to the effects of
sediment instability and completely reliant on stable fine sediment
habitat patches. Excessive amounts of sediment and particulate matter
can interfere with key aspects of mussel biology. The availability of
stable sediment patches may help explain the restricted distribution in
mainstem versus tributary environments, as the fat threeridge has never
been found in a tributary stream. By their nature, tributaries are
smaller in size than mainstems and have more dynamic flows and sediment
transport (Fritz et al. 2018, p. 6). Thus, the fat threeridge is
ecologically restricted/isolated to large river systems in low gradient
areas with stable, very fine sediment patches (Service 2021, pp. 22-
23).
Within its range in the ACF River Basin, fat threeridge is found in
mainstem habitats in the Flint, Apalachicola, and Chipola rivers; there
are no known collections from the Chattahoochee River (Service 2021, p.
26). At the time the fat threeridge was listed in 1998, there were very
few existing records of the species, with the most seen at a site being
6 individuals (63 FR 12666). Current estimates in the middle
Appalachicola alone are upwards of 7.7 million individuals (Service
2021, p. 47).
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. On April 5, 2024, jointly with the National Marine
Fisheries Service, the Service issued a final rule that revised the
regulations in 50 CFR part 424 regarding how we add, remove, and
reclassify endangered and threatened species and what criteria we
[[Page 85914]]
apply when designating listed species' critical habitat (89 FR 24300).
This final rule is now in effect. 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. The determination to delist a
species must be based on an analysis of the same five factors.
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 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 which is
further described in the 2009 Memorandum Opinion on the foreseeable
future from the Department of the Interior, Office of the Solicitor (M-
37021, January 16, 2009; ``M- Opinion,'' available online at <a href="https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf">https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf</a>).
The foreseeable future extends as far into the future as the U.S. Fish
and Wildlife Service and National Marine Fisheries Service (hereafter,
the Services) can make reasonably reliable predictions about the
threats to the species and the species' responses to those threats. We
need not identify the foreseeable future in terms of a specific period
of time. We will describe the foreseeable future on a case-by-case
basis, using the best available data and taking into account
considerations such as the species' life-history characteristics,
threat-projection timeframes, and environmental variability. In other
words, the foreseeable future is the period of time over which we can
make reasonably reliable predictions. ``Reliable'' does not mean
``certain''; it means sufficient to provide a reasonable degree of
confidence in the prediction, in light of the conservation purposes of
the Act.
Analytical Framework
The SSA reports document the results of our comprehensive
biological review of the best scientific and commercial data regarding
the status of the Chipola slabshell and fat threeridge, including
assessments of the potential threats to these species. The SSA reports
do not represent our decisions on whether these species should be
proposed for delisting. However, they do 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 Chipola slabshell and fat threeridge 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 each species' ecological requirements for survival and
reproduction at the individual, population, and species levels, and
described the beneficial and risk factors influencing these species'
viability.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated individual species' life-history
needs. The next stage involved an assessment of the historical and
current condition of these species' demographics and habitat
characteristics, including an explanation of how these species arrived
at their current condition. The final stage of the SSA involved making
predictions about each 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 these species to sustain populations in the
wild over time. We use this information to inform our regulatory
decisions.
The following is a summary of the key results and conclusions from
the SSA reports; the full SSA reports can be found at Docket No. FWS-
R4-ES-2024-0051 on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of each
species and their resources, and the threats that influence these
species' current and future conditions, in order to assess both
species' overall viability and the risks to that viability. In
addition, the SSA reports (Service 2020, entire; Service 2021, entire)
document our comprehensive biological status review
[[Page 85915]]
for each species, including an assessment of the potential threats to
each species. The following is a summary of these status reviews and
the best available information gathered since that time that have
informed these decisions.
Species Needs
Both Chipola slabshell and fat threeridge share similar habitat
needs, including stable stream channels; permanently flowing water to
adequately deliver oxygen, enable passive reproduction, support host
fish, deliver food items to the sedentary juvenile and adult life
stages, and remove wastes; and good water quality (i.e., free from
harmful toxicants (such as chlorine, unionized ammonia, heavy metals,
salts, pesticides), or at low enough concentrations to avoid adverse
effects). The Chipola slabshell prefers predominantly sand, gravel,
and/or cobble stream substrate with low to moderate amounts of silt and
clay (Service 2020, pp. 15-16), whereas the fat threeridge prefers
stable fine sediment habitat patches (Service 2021, p. 22).
Analysis Units
The Chipola slabshell consists of a single, panmictic population
within the Chipola River basin; we delineated three subpopulations
(i.e., management units, MUs) to account for the two natural breaks in
connectivity (Service 2020, pp. 64-65). Although these breaks do not
prevent dispersal of infected host fish between subpopulations of the
Chipola slabshell, we delineated the MUs based on the potential
barriers to dispersal and genetic exchange. Since our knowledge of the
level of genetic diversity is limited, it is possible MUs exhibit some
natural variation in genetic diversity. Each subpopulation was broken
into U.S. Geological Survey (USGS) 10-digit hydrologic unit codes (HUC-
10s) as MUs (see table 1, below). These units reflect a spatial scale
for which mussel survey data were available.
Table 1--HUC-10s for Each Chipola Slabshell Management Unit (MU)
------------------------------------------------------------------------
MU HUC-10s
------------------------------------------------------------------------
1......................................... River Styx & Douglas Slough.
2......................................... Merritts Mill Pond-South.
Mill Creek.
Tenmile Creek.
Dead Lake.
3......................................... Marshall Creek.
Cowarts Creek.
Merritts Mill Pond-North.
------------------------------------------------------------------------
The fat threeridge also consists of a single population; we
delineated six analysis units (HUC-10s) within the Flint, Chipola, and
Apalachicola Rivers, based on potential reproductive isolation and/or
unique geomorphology, available current occurrence records, and expert
input (Service 2021, pp. 51-52).
Threats
The primary threats affecting viability of both mussel species are
predominantly related to historical land use practices resulting in the
destruction, modification, or curtailment of these species' habitat or
range (Factor A), ultimately affecting water quality and flow regime
(i.e., water quantity). They are: (1) sedimentation; (2) impoundments;
(3) agriculture; and (4) urbanization. Existing regulatory mechanisms
(Factor D) and conservation actions have benefited the species, thus
ameliorating many threats. Other threats such as invasive species
(Factor C) likely have had some negative effects on the two mussel
species, as described in the SSA reports, but were not considered
primary threats that affect the species' overall viability (Service
2020, pp. 40-41; Service 2021, p. 76). Our analyses also considered the
effects of climate change (Factor E), but sea level rise (SLR) was only
examined for fat threeridge based upon the potential of SLR to affect
the lower portion of its range.
Sedimentation
The primary listing factor for both the Chipola slabshell and fat
threeridge was related to habitat modification, specifically the issue
of increased sedimentation which causes turbidity from erosion (Service
2020, p. 27; Service 2021, p. 76). Sedimentation is one of the most
significant pollution sources for aquatic organisms and is a major
factor in overall mussel declines (Service 2020, p. 31), as excessive
amounts of sediment and particulate matter can interfere with key
aspects of mussel biology (Service 2021, p. 24).
Canopy, or riparian buffers, provide the conditions for stable
stream channels, delivery of food items, and improved overall water
quality because of their ability to filter runoff. Activities related
to dredging, snag removal, agriculture, logging, and urban development
are usually common sources of erosion and sedimentation. Dredging was a
widespread, intensive, and frequent disturbance within the Apalachicola
River that was detrimental to both species at the time of listing.
However, over the past 20 years, dredging practices have been
restricted through regulations such that very little dredging has
occurred, and future dredging activities are expected to be limited.
Following the cessation of widespread dredging, signs of habitat
recovery have been observed, indicating improved habitat stability for
fat threeridge and other freshwater mussels (including Chipola
slabshell) in the Apalachicola River (Service 2021, pp. 58-59).
In 2009, we conducted a basin threats assessment for the Chipola
River in order to identify and reduce sedimentation risks to aquatic
life. Unpaved roads were identified as primary contributors of sandy
materials that are easily eroded and transported to stream corridors.
All unpaved road-stream crossing sites were ranked and prioritized for
subsequent restoration practices, and proximity to sites of listed
species and their habitat was a primary consideration (Service 2020, p.
55). We began unpaved stream crossing restoration efforts in 2013, in
partnership with the Florida Fish and Wildlife Commission (FWC), and
several projects have reduced sediment inputs (Service 2020, p. 56).
Partnerships and programs have had success in restoring and
reducing sediment inputs in priority stream reaches that have been
identified as highly erodible. We and our partners, including but not
limited to the University of Florida's Institute of Food and
Agricultural Sciences Extension, Northwest Florida's Water Management
District, Florida Department of Agriculture and Conserver Services,
Natural Resources Conservation Service, FWC, the U.S. Forest Service,
and many landowners (National Fish Habitat Partnership 2020,
unpaginated), have successfully restored over 8 km (5 mi) of streams in
the Chipola River Basin and continue to implement stream restoration
projects (for example, bank stabilization, solar wells, livestock
exclusion fencing, riparian restoration, low-water crossings, and
reshaping of spring-fed tributaries) to reduce sediment inputs. The
Southeast Aquatic Resources Partnership continues to use a Chipola
River Basin threats assessment to reduce sedimentation in the basin and
identify potential barriers to fish passage (Service 2020 pp. 55-56).
Impoundments
Impoundments can alter downstream water quality and riverine
habitat (Service 2020, p. 28). The most consequential direct effects to
Chipola slabshell and fat threeridge from impoundments include upstream
and downstream flow effects, as well as the
[[Page 85916]]
loss of and fragmentation of riverine habitat. Pre-existing dams that
fragment and inundate habitat and alter natural flow are part of
existing baseline conditions for these species and are unlikely to
change substantially in the near future (Service 2020, pp. 33-36;
Service 2021, p. 112). Impoundments remain within tributaries of the
Chipola River, but the mainstem, which contains the majority of Chipola
slabshell, as well as critical habitat for fat threeridge, is
unobstructed (Service 2020, p. 28; Service 2021, p. 107). The main stem
of the Chipola River formerly contained one impoundment, the Dead Lake
Dam, which was removed in 1987. The final obstructions to natural flow
in the channel were removed in 1989. The dam removal returned
connectivity and natural flow conditions to the river, but the local
sediment and detritus load is likely still high (Service 2021, p. 81).
However, even with the accumulated detritus, the number of fish species
almost doubled after the dam was removed, with anadromous fish able to
travel through the lake to spawn or seek critical thermal refugia in
the upper Chipola River (Service 2020, p. 34).
Following the return of connectivity and natural flow regime of
Dead Lakes, habitat conditions are anticipated to become more stable
over time. Stable stream habitats are formed and maintained by natural
flow regimes, channel features (dimension, pattern, and profile), and
natural sediment input to the system through periodic flooding. These
events help maintain connectivity and interaction with the floodplain,
and consistently transport sediment load over time, such that the
stream bed neither degrades nor aggrades (Service 2021, p. 22).
Agriculture
Agriculture is the largest groundwater consumer in the ACF River
Basin accounting for 35 percent of all water withdrawals in 2010. Of
the groundwater withdrawn in the ACF River Basin, 89 percent was
withdrawn in Georgia, and about 11 percent was withdrawn in Alabama and
Florida during 2010 to provide irrigation for approximately 736,200
acres (ac) (297,930 hectares (ha)) (Service 2021, p. 87). These
groundwater withdrawals exacerbate drought conditions during dry years,
which can affect both tributaries and main river channels (Service
2021, p. 86).
Water pollutants associated with agricultural activity may also
adversely affect mussels. Ammonia is associated with nitrogenous
fertilizers, wastewater from animal feedlots (livestock waste), and the
effluents of older municipal wastewater treatment plants. While
nitrogen from wastewater inputs originating from septic and sewer
sources are also associated with urban centers, other forms of
pollution are unique to these agricultural areas (Service 2020, p. 30).
Properly implemented agricultural best management practices (BMPs) have
improved the water quality in several basins where Chipola slabshell
and fat threeridge occur. Implementing BMPs has reduced thousands of
pounds of agricultural nitrogen inputs from fertilizers and livestock
waste (Service 2020, p. 51).
Agricultural land use is highest in the Lower Flint River, so
impacts from stressors associated with agricultural activity could
limit fat threeridge in the future. However, land use in the sub-basins
with fat threeridge present has remained relatively stable from 2000-
2016. A large portion of each sub-basin is also forested, which
provides an effective buffer for maintaining sufficient river
baseflows, permeability, and reducing overall flooding impacts (Service
2021, p. 87). Fat threeridge will likely maintain resiliency in larger
river and mainstem habitats in the ACF River Basin, including the Lower
Flint, if adequate water quality and quantity continue at current
levels (Service 2021, pp. 129-130).
Urbanization
Urban development not only causes habitat loss and fragmentation,
but it also contributes to habitat degradation through storm water
runoff and nonpoint source pollution. The term ``development'' refers
to urbanization of the landscape, including (but not limited to) land
conversion for residential, commercial, and industrial uses and the
accompanying infrastructure. Urbanization effects may include
alterations to water quality, water quantity, and instream and
streamside habitat (Ren et al. 2003, p. 649; Wilson 2015, p. 424). The
effects on habitat also include variability in streamflow, typically
increasing the extent and volume of water entering a stream after a
storm and decreasing the time it takes for the water to travel over the
land before entering the stream (Giddings et al. 2009, p. 1).
Freshwater mussel populations experience reduced abundance, species
richness, reproduction, growth, and survival stemming from the impacts
of urbanization on water and habitat quality (Diamond and Serveiss
2001, p. 4716; Gangloff et al. 2009, p. 198; Cao et al. 2013, pp. 1212-
1214; Gillis et al. 2017, pp. 674-679). While there are some parts of
both the Chipola slabshell's range and the fat threeridge's range that
are affected by urbanization, it does not rise to the level that it is
affecting current viability (see Current Conditions below).
Additional Water Quality and Quantity Considerations
Influences on the viability of the Chipola slabshell and fat
threeridge include habitat factors such as water quantity (flow)
(Service 2020, p. 28). Flow impacts are varied between low flow and
high flow conditions. When water flows decrease, the concentration of
water pollutants increases, thus increasing the adverse effects that
can negatively impact the freshwater mussels, such as Chipola slabshell
and fat threeridge, and their habitat (Service 2020, p. 32; Service
2021, p. 21).
High-flow volumes can be both harmful and beneficial for freshwater
mussels. Floods are often associated with habitat destruction and
direct mortality, both to juveniles and adults that are stranded in
unsuitable habitats (Service 2020, p. 32; Service 2021, p. 65). Floods
can also increase the potential for shear stress events to occur. Shear
stress is a critical factor in affecting displacement during high-flow
events where substrates are unstable, conditions are generally poor for
mussel habitation. However, floods can also help remove accumulated
silt deposits, algal growth and harmful organic material from
sediments, improving habitat for juvenile mussels. It is likely that
large woody debris can also help to potentially stabilize sediments in
the Coastal Plains ecoregion where Chipola slabshell and fat threeridge
occur, and as a result these areas are expected to be the most stable
during high flows (Service 2020, p. 32).
Water quantity can become limited by withdrawals and be exacerbated
during extreme drought events and periods of low flow. Groundwater
recharge provides water to aquifers and springsheds, and alterations to
groundwater removal can alter surface water flow impacting spring flow
and available surface water (Service 2020, p. 41). Under moderate-flow
conditions, groundwater makes up the majority of the Chipola River's
discharge and the quality of water discharged from the Chipola River
springs is predominantly determined by the quality of groundwater in
the Floridan Aquifer (Service 2020, p. 19). The Chipola River's
baseflow is derived principally from aquifers, therefore it is not as
susceptible to drought conditions. In addition, Chipola slabshell has
been found to occupy areas 1 to 2 meters (m) (3.3 to 6.6 feet (ft))
below the water
[[Page 85917]]
surface, providing a buffer against the effects of low flow conditions.
Fat threeridge has also persisted and arguably increased in abundance
through these periods of low flow (Service 2021, pg. 103).
For more information regarding threats, see chapter 3 of the
Chipola slabshell SSA report and chapter 5 of the fat threeridge SSA
report (Service 2020, pp. 27-140; Service 2021, pp. 76-130).
Climate Change
Impacts of climate changes can have direct effects or be driven by
one or more factors working synergistically as indirect effects on
species. These effects may be neutral, positive, or negative and they
may change over time. Despite the recognition of potential climate
effects on ecosystem processes, there is uncertainty about what the
exact climate future for the southeastern United States will be and how
ecosystems and species in this region will respond. The greatest threat
from climate change may come from synergistic effects. That is, factors
associated with a changing climate may act as risk multipliers by
increasing the risk and severity of more imminent threats, especially
for rivers in wide flood plains where stream channels have room to
migrate (Elliot et al. 2014, pp. 67-68). As a result, impacts from land
use change might be exacerbated under even a mild to moderate climate
future. A suite of potential hydrological impacts to waters of the
southeastern United States is possible under conditions of climate
change, but climate models generally predict increases in extreme
rainfall events and droughts of greater duration and intensity (Carter
et al. 2018, pp. 745-746).
Flooding
Tropical storms occur across the range of Chipola slabshell and fat
threeridge, and they have become more intense during the past 20 years.
The wind speeds and rainfall associated with hurricanes are likely to
increase as the climate continues to warm (United States Environmental
Protection Agency (USEPA) 2016b, p. 1, USEPA 2016c, p. 1). In October
2018, Hurricane Michael substantially impacted northwest Florida.
According to a report by the Florida Forest Service (FFS), more than
2.8 million ac (1.13 million ha) of forest land were damaged by storm
winds. The Chipola River experienced severe impacts, where 75 percent
of upland and bottomland trees were damaged (FFS 2018, pp. 1, 4-5).
However, high woody debris loading has greatly contributed to the
formation of stable, fine sediment habitat in the Lower Chipola River
(Kaeser et al. 2019, p. 667), resulting in net positive effects of
blowdown for Chipola slabshell and fat threeridge assuming forest cover
regenerates.
The increased intensity of hurricanes as well as more frequent
high-intensity precipitation events could also increase inland
flooding. The precipitation received during heavy storms has increased
by 27 percent in the Southeast with the trend for increasingly heavy
rainfall events likely to continue into the future (USEPA 2016b, p. 2).
With these heavy rainfall events comes flooding, as rivers overtop
their banks more frequently, and more water accumulates in low-lying
areas that drain slowly. Restoring and preserving flood protection and
nutrient reduction capabilities of forested lands along the Chipola
River is vital (Northwest Florida Water Management District (NWFWMD)
2018, p. 6).
Drought
Long-term climate records suggest that decade-long ``mega-
droughts'' have occurred periodically during the past 700 years in the
southeastern United States, including in the ACF River Basin (Stahle et
al. 2007, p. 147). Projections for the ACF watershed indicate that
future droughts are likely to be more intense (Yao and Georgakakos
2011, entire). This suggests that while the recently observed droughts
in 2006-2008 and 2010-2012 were exceptional based on our recent <100-
year period of record, they may not be exceptional compared to historic
episodes (Pederson et al. 2012, entire).
The duration and severity of droughts may vary within the ranges of
Chipola slabshell and fat threeridge. Droughts are likely to be more
severe in some locations as periods without rain may be longer and very
hot days will be more frequent. Dry spells are expected to be up to 20
days shorter during the cold season in the southern half of Florida,
and up to 20 days longer for the same season in Alabama (Keellings and
Engstrom 2019, p. 1). While more intense cold season droughts might not
be as stressful for mussels as intensification of droughts during the
warm season would be, a cool season drought may limit recharge and
storage of water in both natural and anthropogenic reservoirs (Engstrom
and Keellings 2018, p. 261; Keellings and Engstrom 2019, p. 3). More
frequent or severe droughts may reduce streamflow in some areas. In
Alabama, the total amount of water running off into rivers or
recharging ground water is likely to decline 2.5 to 5 percent, as
increased evaporation offsets the greater rainfall (USEPA 2016b, p. 2).
Low flows have decreased in the southeastern United States between 1940
and 2019, meaning streams are carrying less water at low flow than
historically recorded (USEPA 2016a, p. 2). Low flows have not gone
below 200 cubic feet per second (cfs) in the Chipola River in the
recent past (1986 to 2019; USGS National Water Resources, 2019,
entire), but may in the future.
The Chipola River is a spring-fed river with baseflow derived
principally from aquifers, and therefore is not as susceptible to
drought conditions derived from changes in precipitation patterns as it
is to alterations in groundwater withdrawals. Mussel sites in the
Chipola River generally have slopes greater than 20 percent, which
helps to limit mussel mortality to less than 1 percent of the local
population during low flow events (Service 2016b, p. 125). In addition,
Chipola slabshell have been found to occupy areas 1 to 2 m (3.3 to 6.6
ft) below the water surface, providing a buffer against the effects of
low flow conditions (Service 2016b, p. 129). Even during severe drought
conditions in 2007, Cowarts Creek (which joins Marshall Creek to form
the Chipola River) did not exhibit signs of mussel mortality (Garner et
al. 2009, p. 693). Cowarts Creek retained adequate dissolved oxygen
(6.5 milligrams per liter (mg/L) (81.5 percent saturation)) and
temperature (27 [deg]C (81 [deg]F), though the flow was sluggish and
phytoplankton seemed elevated (Garner et al. 2009, p. 688).
Sea Level Rise
Most freshwater mussels are intolerant of saline conditions. The
potential for sea level rise (SLR), and thus intrusion of saline
conditions, is considered for the fat threeridge range; however, the
Chipola slabshell's range is not likely to be affected. Exposure to
saline conditions (salt at 3 to 6 parts per trillion (ppt)) can
decrease the reproduction and survival of freshwater mussels (Blakeslee
et al. 2013, p. 2849). The upper limit for exposure of most adult
unionid mussels to long-term salinity stress is < 6 ppt, which may be
consistent with fat threeridge tolerances. Fat threeridge is not known
to occur below the point of tidal influence in the Apalachicola River,
where salt exposure is expected to be lethal. An increase in salinity
of fresh waters through the intrusion of seawater associated with sea
level rise will likely modify community composition of unionids in
affected areas, eliminating or at least reducing the abundance of
species that
[[Page 85918]]
are less adapted to increased salinity (Johnson et al. 2018, p. 67).
Climatic changes, including SLR and shifts in seasonal
precipitation, temperature, and storm cycles, are major threats to
south Florida. Various studies (University of Florida Geoplan 2015, p.
13; The Nature Conservancy 2011, p. 4-6; Sweet et al. 2017, p. 22-23)
have developed scenarios that range from less than 0.3 m to 3.2 m (1 to
10.4 ft) of SLR in the south Florida by 2100. Tidal gauges around
Florida have shown 25 cm (10 in) of SLR since 1913, with an increase in
SLR of 2.56 mm/year (0.1 inch/year) from 1967 to 2019, equivalent to 25
cm (9.8 inches) in 100 years more locally (NOAA 2021, n.p.). This
recent acceleration suggests that the intermediate to high SLR
scenarios are more likely to occur than the low and intermediate-low
scenarios (Sweet et al. 2022, pp. 20-21). Sea level rise since 2000 has
generally been within the trajectory of the Intermediate-High scenario,
but it is important to note the trajectory could change throughout the
century. Rapid ice sheet collapse in Antarctica could move SLR from the
intermediate to the high scenario by the end of the century (Sweet et
al. 2022, p. 26). Under the high scenario, some areas supporting fat
threeridge (e.g., the Lower Apalachicola) will likely become partially
inundated (i.e., under water) at some point during this century
(Service 2021, p. 102).
Conservation Efforts and Regulatory Mechanisms
Since the listing of Chipola slabshell as an endangered species and
fat threeridge as a threatened species under the Act in 1998, Federal
agencies have been required under section 7 of the Act to coordinate
with us to ensure actions that they carry out, fund, or authorize will
not jeopardize either species' continued existence or destroy or
adversely modify the critical habitat designated for these species in
2007. This requirement has protected both Chipola slabshell and fat
threeridge throughout most of their ranges. Both Federal and State
regulations are relevant to the maintenance of water quality where
Chipola slabshell and fat threeridge occur.
Water quantity can become limited by agricultural, irrigation,
municipal, and industrial withdrawals. Such withdrawals can be
exacerbated during extreme drought events and periods of low flow.
Groundwater recharge provides water to aquifers and springsheds, and
alterations to groundwater removal can alter surface water flow
impacting spring flow and available surface water. The State of Florida
establishes minimum flow limits (MFLs) to identify the limit at which
withdrawals would be significantly harmful to the water resources or
ecology of an area. Water reservation is a legal mechanism in Florida
that functions to set aside water from consumptive uses for the
protection of fish and wildlife or public health and safety (2023
Florida Statutes at section 373.223). Water reservations and MFLs are
both important tools to ensure an adequate supply of water for citizens
and environment. There is no known comparable mechanism to protect
flows in Alabama. Water reservations were established for the Chipola
and Apalachicola rivers in 2006 (Florida Administrative Code, rule 40A-
2.223). The magnitude, duration and frequency of observed flows are
reserved, essentially in total, for the protection of fish and wildlife
of the Chipola River, Apalachicola River, associated floodplains, and
Apalachicola Bay.
Federal guidelines are in place to minimize alterations to flow
regimes. The Service and USEPA proposed instream flow guidelines for
protecting riverine ecosystems under a possible interstate water
allocation formula between Alabama, Florida, and Georgia for the ACF
Basin. Although the three States failed to agree upon an allocation
formula and the ACF compact authorizing their negotiations expired in
2003, the Service has applied the instream flow guidelines in
consultations with Federal agencies on actions affecting the species
addressed in this proposed rule. At minimum, the Environmental Resource
Permit Program within the USEPA regulates the construction, alteration,
maintenance, removal, modification and operation of all activities in
uplands, wetlands and all other surface waters that alter, divert and
change the flow of surface waters. Both State and Federal permits may
be required to alter wetlands and other surface waters.
Future water quantity models in the Chipola River Basin have
projected adequate water supply for citizens and the environment
through 2045, even in drought years (NWFWMD 2023, p. ix). Water flows
for most of the Chipola slabshell's and fat threeridge's occupied range
are protected through consumptive uses by water reservation (legal
protection), while other areas are supported by ground water
contributions from springs during drought (Service 2020, pp. 96-139;
Service 2021, p. 112). Water quantity models are updated every 5 years
to ensure sufficient supply planning.
Regional water plans in Georgia are developed in accordance with
the Georgia Comprehensive State-wide Water Management Plan (State water
plan), which was adopted by the General Assembly in January 2008. The
State water plan requires the preparation of regional water development
and conservation plans to manage water resources in a sustainable
manner through 2050. A water conservation plan is required of all
permit holders operating in the Flint River basin. This requirement
will benefit fat threeridge resiliency in the future by ensuring
permits are sufficiently protective of necessary water quantity and
quality. These plans detail best water management practices to be
followed, provide direction for funding conservation practices,
describe permit conditions for withdrawal permits, and provide guidance
for how to minimize and control water loss (Georgia Department of
Natural Resources (GADNR) 2006, pp. 161-163).
Minimum water quality standards have been set by Federal agencies
both through the Clean Water Act (CWA; 33 U.S.C. 1251 et seq.) and
other initiatives. The CWA is a Federal law that regulates the
discharge of pollutants into surface waters, including lakes, rivers,
streams, wetlands, and coastal areas. USEPA and the Service and
National Marine Fisheries Service agreed to a national consultation on
the CWA Section 304(a) aquatic life criteria as part of a Memorandum of
Agreement regarding interagency coordination under the CWA and the Act
(66 FR 11202; February 2, 2001). In 2013, the USEPA released new
ammonia criteria that included acute and chronic toxicity testing for
13 freshwater mussels, thus leading to an improved understanding of
ammonia toxicity and setting a more protective ammonia criteria value
for freshwater mussels (USEPA 2013, p. xi). In 2016, the Florida
Department of Environmental Protection (FDEP) adopted the chronic
criteria for ammonia as both the acute and chronic values (1.408 mg/L),
therefore improving the ammonia standard even further for the
conservation of freshwater mussels statewide (USEPA 2016a, entire).
Georgia Department of Natural Resources' (GADNR) Environmental
Protection Division (EPD) also implements the 2013 ammonia criteria as
part of their National Pollutant Discharge Elimination System (NPDES)
permitting process (GADNR 2022, pp. A-16-17).
Florida has established water classifications that promote water
quality standards that are more stringent than those of the CWA. The
Florida
[[Page 85919]]
Department of Environmental Protection (FDEP) designates Outstanding
Florida Waters (OFWs) under 2023 Florida Statutes section 403.061(27).
An OFW is defined by FDEP as a waterbody worthy of special protection
because of its natural attributes. In general, FDEP cannot issue
permits for direct discharges to OFWs that would lower ambient
(existing) water quality. FDEP also may not issue permits for indirect
discharges that would significantly degrade a nearby waterbody
designated as an OFW. The majority of waterbodies and segments in the
range of Chipola slabshell and fat threeridge receive regulatory
protection through designation as OFWs in addition to protections under
their surface water classification as class III waterbodies, which
include designated uses for fish consumption, recreation, and
propagation and maintenance of a healthy, well-balanced population of
fish and wildlife (Service 2020, appendix B). Further, the Florida
Springs and Aquifer Protection Act of 2016 (2023 Florida Statutes at
section 373.801-373.813) established Outstanding Florida Springs (OFSs)
that require additional protections to ensure their conservation and
restoration. Under this act, the State of Florida designated the
Jackson Blue Spring within the Chipola River Basin as an OFS.
Section 303(d) of the CWA (33 U.S.C. 1251 et seq.) requires states
to identify waters that do not fully support their designated use
classification, and so are deemed impaired. The most recent assessments
within the range of Chipola slabshell and fat threeridge were completed
by the FDEP and Alabama Department of Environmental Management (ADEM)
as of 2018 and GDNR in 2022. Impaired water bodies are placed on each
State's 303(d) list, and a total maximum daily load (TMDL) must be
developed for the pollutant of concern. A TMDL is an estimate of the
total load of pollutants that a segment of water can receive without
exceeding applicable water quality criteria. There are several reasons
why an impaired waterbody may be delisted, including but not limited
to: a subsequent assessment determining that a waterbody-parameter is
no longer impaired based on current water quality standards, if there
has been a TMDL completed for the verified impaired parameter; or if a
flaw in a previous assessment has been determined.
Impaired waterbodies within watersheds occupied by Chipola
slabshell and fat threeridge are largely impacted by fecal coliform.
The standards for fecal coliform (e.g., Escherichia coli) relate to
human health and do not necessarily reflect levels that would be
harmful to mussels. While some waters are impaired due to nutrients or
organic enrichment, these standards are in place to protect human
health and do not relate directly to the potential effects of nutrients
such as nitrogen on mussels. Monitoring results in Georgia indicate
that approximately 60 percent of the streams are impaired for fecal
coliform bacteria, with less than 2 percent for ammonia toxicity, which
would adversely affect mussels, and those ammonia-impaired streams are
not within the range of fat threeridge (GADNR 2022, p. 3-3). The
numeric nutrient criteria (NNC) and ammonia standard in Florida reflect
nutrient impact thresholds for mussels. This criterion includes total
nitrogen (TN) and total phosphorus (TP) for flowing freshwaters. The TN
NNC threshold concentrations are 0.67 mg/L for the Chipola River
(Panhandle West), which is well below the newly adopted 1.408 mg/L
ammonia concentration in Florida (Service 2016a, p. 6). Alabama also
has a nitrate/nitrite nitrogen and ammonia standard in addition to
other standards that are more representative of the potential harm to
mussels than the nutrient or organic enrichment standard, which are no
longer used as part of the water quality assessment process (ADEM 2018,
pp. 11-14). Many of the delisted waterbodies were previously impaired
due to elevated mercury levels in fish, which is also a human-health
related standard (FDEP 2013, p. ii) that does not reflect levels that
would be harmful to mussels. Given the parameters resulting in
impairment and the establishment of TMDLs, water quality within the
range of Chipola slabshell and fat threeridge is considered unimpaired
in regards to freshwater mussel water quality thresholds.
Current Conditions
Under the SSA framework, we assessed current resiliency,
redundancy, and representation for Chipola slabshell and fat
threeridge. Resiliency reflects a species' ability to withstand
stochastic events (arising from random factors). Resiliency is measured
at the population-level using metrics that characterize population
health such as demographic rates and population size. We also consider
the nature and extent of stressors to a species that could limit
resiliency. Populations demonstrating resiliency are better able to
withstand perturbations associated with demographic stochasticity
(e.g., fluctuations in birth or mortality rates), environmental
stochasticity (e.g., variation in precipitation or temperature), and
anthropogenic activities. For the species to be considered viable,
there must be adequate redundancy (suitable number, distribution, and
connectivity of populations to allow the species to withstand
catastrophic events). Redundancy improves with increasing numbers of
populations distributed across the species range, and connectivity
(either natural or human-facilitated) that allows connected populations
to ``rescue'' each other after catastrophes. We can best gauge
redundancy by analyzing the number and distribution of populations
relative to the scale of anticipated species-relevant catastrophic
events. Representation refers to the genetic and environmental
diversity within and among populations that contributes to the ability
of the species to respond and adapt to changing environmental
conditions over time. The more representation, or diversity, a species
has, the more it can adapt to changes (natural or human caused) in its
environment. We can best gauge representation by examining the breadth
of genetic, phenotypic, and ecological diversity found within a species
and its ability to disperse and colonize new areas. For more
information, see chapter 4 in each of the SSA reports (Service 2020,
pp. 61-92; Service 2021, pp. 51-75).
Chipola Slabshell
Our current condition analysis for the singular Chipola slabshell
population describes the conditions of each of the three MUs (see table
1, above). The magnitude and scale of potential impacts to Chipola
slabshell or its habitat by a given threat are considered based on the
condition of the watershed. Each HUC-10 watershed within the three MUs
was rated as currently being in poor, fair, good, or excellent
condition for each of the resiliency factors. Resiliency measures
included two population factors (occupancy and abundance/recruitment)
and two habitat factors (sedimentation and canopy) that were scored to
provide overall MU resiliency (table 2, below). The four condition
categories were then converted to numerical ranks and then a weighted
average of the factor scores was calculated to generate an overall
resiliency score. See the SSA report for details on the scoring
methodology (Service 2020, pp. 89-91).
[[Page 85920]]
Table 2--Summary of Condition Categories and Resiliency Factors To Assess Chipola Slabshell's Current Resiliency
----------------------------------------------------------------------------------------------------------------
Population factors (since 2005) Habitat factors
----------------------------------------------------------------------------------
Sedimentation index
Abundance & ((a) Density of road Canopy (% 200-
Condition category Occupancy recruitment (# crossings and ft buffer with
(proportion of individuals and transmission lines, <ls-thn-eq>=50%
occupied HUC-10s) evidence of percent non-natural canopy cover
reproduction) cover, and (b) soil within assessed
loss potential) stream length)
----------------------------------------------------------------------------------------------------------------
Excellent.................... Consistent >100 (live) during a 0-0.08: (a) minimal; >90.
occupation in given sampling (b) low.
addition to newly event; suggests a
occupied. healthy population
(e.g., likely
ongoing
recruitment).
Good......................... Consistent occupancy 10-100 (live or 0.09-0.23: (a & b) 76 to 90.
dead); more than low.
one age class
represented.
Fair......................... <50% Decreased <10 individuals 0.24-0.36: (a & b) 50 to 75.
occupancy. (live or dead); moderate.
potentially
represented only by
older individuals
with limited
recruitment.
Poor......................... >=50% Decreased Only dead observed; 0.37-0.76: (a) <50.
occupancy. population maximal; (b)
reduction likely moderate to high.
not offset by
recruitment.
[Oslash]..................... No occupancy in HUC- No records.......... N/A................. N/A.
10.
----------------------------------------------------------------------------------------------------------------
Within the single population for Chipola slabshell, there are
currently two MUs that demonstrate moderate to high resiliency and one
that has low resiliency (table 3, below). MU 1 has only one watershed,
whereas MU 2 and MU 3 are each comprised of several watersheds.
Although the range is narrow (i.e., solely within the Chipola River),
current occupancy of the entire range is evident. Sedimentation, a risk
to all mussels, is not a threat in the Chipola River Basin, as
indicated by good to excellent indices in all but two areas of MU 3.
Although the resiliency of MU 3 is overall low, we note that occupancy
is excellent throughout this MU. The SSA report noted that the species
is thought to occur in relatively low densities naturally, and the
northern part of the range in MU 3 is considered marginal habitat for
the slabshell (Service 2020, p. 92). Thus, Chipola slabshell exhibits
sufficient resiliency throughout its current range, contributing to
overall species viability.
Table 3--Summary of Current Resiliency for Chipola Slabshell Management Units (MUs)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population factors Habitat factors
----------------------------------------------------------------------- Overall MU
MU HUC-10s Abundance & Sedimentation Watershed score resiliency
Occupancy reproduction index Canopy
--------------------------------------------------------------------------------------------------------------------------------------------------------
1............................ River Styx & Excellent....... Good............ Excellent....... Excellent...... High........... High.
Douglas Slough.
2............................ Merritts Mill Good............ Good............ Good............ Excellent...... Moderate....... Moderate.
Pond--South.
Mill Creek...... Good............ Excellent....... Good............ Good........... Moderate.......
Tenmile Creek... Good............ Excellent....... Excellent....... Good........... High...........
Dead Lake....... Good............ Good............ Excellent....... Good........... Moderate.......
3............................ Marshall Creek.. Excellent....... Fair............ Fair............ Good........... Low............ Low.
Cowarts Creek... Excellent....... Good............ Fair............ Good........... Moderate.......
Merritts Mill Excellent....... Fair............ Good............ Excellent...... Moderate.......
Pond--North.
--------------------------------------------------------------------------------------------------------------------------------------------------------
High redundancy for Chipola slabshell is defined as multiple
resilient MUs distributed throughout the species' range. Two-thirds of
the species' range has moderate to high levels of resiliency. We
considered all three MUs as contributing to redundancy, thus enabling
the species to withstand catastrophic events. Most of the population is
not currently at risk from habitat modification, indicated by high-
ranking habitat factors and watershed scores (table 3, above), and
there is a high degree of land protection where the Chipola slabshell
habitat is buffered by forested public lands, protecting water quality
and ensuring the viability of the population and ultimately the species
as a whole.
Representation, which refers to the breadth of genetic and
environmental diversity within and among populations, reflects the
species' adaptive capacity. Currently, there is limited information
pertaining to genetic variation and no evidence to support delineating
multiple representation units for Chipola slabshell (Service 2020, p.
74). However, the breadth of environmental diversity within the range
(e.g., the north-south gradient with headwater streams to mainstems of
the Chipola River and the Apalachicola River) is currently occupied.
Our knowledge of the level of genetic diversity for Chipola slabshell
is
[[Page 85921]]
limited; however, it is possible subpopulations exhibit some natural
variation in genetic diversity. Chipola slabshell representation has
not likely changed over time, but as a narrow endemic, the species'
adaptive potential is limited.
Fat Threeridge
Current condition for fat threeridge describes the condition of the
six analysis units. Characteristics of resiliency for fat threeridge
include evidence of stable or increasing population trends, and
evidence of reproduction (either direct observation of juveniles, or of
multiple age classes as inferred by length data). An adequate number of
resilient populations should be distributed throughout the species
range to both protect adaptive capacity of the species, and protect
from catastrophic events. We analyzed the resilience of units within
the range of fat threeridge slightly differently than we did for
Chipola slabshell due to differences in habitat use and perceived
stressors. We assessed demographic resiliency factors including
abundance, recruitment, and occupancy which inform population trends
within the population, and we evaluated habitat resiliency factors
related to water quality and water quantity to establish a baseline
from which to project future condition (table 4, below).
Table 4--Summary of Condition Categories and Resiliency Factors To Assess Current Resiliency for Fat Threeridge
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population factors Habitat factors
Condition category --------------------------------------------------------------------------------------------------------------------
Abundance Recruitment Habitat occupancy Water quality Water quantity
--------------------------------------------------------------------------------------------------------------------------------------------------------
High............................... Recent density and Presence of multiple 71-100% or maximal No known or Lower relative risk
population estimate age classes occupancy. anticipated of direct and
at high end of known (individuals > and contaminant or indirect impacts to
range (>1 per square <50 mm); small sediment problems the survival,
meter (m\2\); >1 individuals (<=35 mm) given the land cover. health, or
million). Increasing detected using recruitment of
or stable population hydraulic dredge species from low
trend. methods. flow events.
Moderate........................... Recent density and Presence of multiple 31-70% or Associated N/A.
population estimate age classes intermediate contaminant or
at lower end of known (individuals > and occupancy. sediment issues are
range (<=1/m\2\ to <50 mm); but no small likely in some areas.
0.11/m\2\; >100k to 1 individuals (<=35 mm)
million). Increasing detected using
or stable population hydraulic dredge
trend. methods.
Low................................ No population Only one size class <30% or minimal Associated Higher relative risk
estimate, generally >=50 mm; no small occupancy. contaminant or of direct and
known to be present individuals (<=35 mm) sediment issues indirect impacts to
at low density (5-10 detected using increases the risk the survival,
individuals minimum hydraulic dredge of negative impacts health, or
and/or <=0.1/m\2\). methods. throughout habitat. recruitment of
Possible stable trend species from low
since 2000, but flow events.
undetectable in the
past.
Very Low........................... Not assessed (N/A).... N/A................... N/A.................. Associated N/A.
contaminant or
sediment levels pose
the highest relative
risk to habitat;
Significant,
widespread, or
prolonged impacts
likely occurring.
[Oslash]........................... None.................. None.................. None................. N/A.................. Intermittent flow; no
survival.
--------------------------------------------------------------------------------------------------------------------------------------------------------
For each population and habitat factor, we considered whether the
analysis units were currently in high, moderate, low, or very low
condition (table 5, below). None of the analysis units are extirpated
or in very low condition. The average of factor rankings was used to
generate an overall resiliency score. For more details on the scoring
methodology, see chapter 4 of the SSA report (Service 2021, pp. 56-70).
Table 5--Fat Threeridge Resiliency Factors and Overall Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population factors Habitat factors
----------------------------------------------------------------------------------------------------
Analysis unit Evidence of Overall resiliency
Abundance recruitment Occupation Water quality Water quantity
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lower Flint..................... Low............... High.............. High.............. Low............... High.............. Moderate.
Upper Apalachicola.............. Moderate.......... High.............. Low............... Moderate.......... High.............. Moderate.
Middle Apalachicola............. High.............. High.............. High.............. High.............. High.............. High.
Lower Apalachicola.............. Moderate.......... High.............. Moderate.......... High.............. High.............. High.
Lower Chipola................... High.............. High.............. High.............. Moderate.......... High.............. High.
Chipola NDL *................... Low............... High.............. High.............. Moderate.......... High.............. Moderate.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* North of Dead Lakes.
Overall, fat threeridge is more abundant (currently estimated at
approximately 12 million individuals) and more widely distributed than
when the species was listed (Service 2021, p. 47). When the species was
listed in 1998, the most individuals seen at a site was 6 (63 FR
12666); current estimates across 164 sites in the middle Appalachicola
alone are over 7.7 million individuals (Service 2021, p. 47). The
positive trends for both population and habitat factors, including
relatively large population sizes, are indicative of populations that
are resilient to stochastic factors. Redundancy for the fat threeridge
is moderate to high, as currently all analysis units in the species
range exhibit moderate to high resiliency. Each unit contributes to
overall species
[[Page 85922]]
redundancy, or the ability of the species to withstand catastrophic
events. Further, the species currently has not had a contraction or
disruption of connectivity (such as from an impoundment) within its
range and this connectivity corresponds to a lowered risk of
extirpation from catastrophic events (Service 2021, p. 72).
The available genetic data for fat threeridge suggests little
variation across the species range. This is supported by the absence of
notable behavioral, morphological, or life history variation. This
suggests genetic variation within the species is low. However, the
species maintains ecological diversity in its occupancy of different
river ``types'' (e.g., small and large river systems) and ecoregions
(e.g., Southeastern Plains and Southern Coastal Plain). Overall,
representation or adaptive capacity of fat threeridge is limited, as
supported by little genetic variation within a narrow geographic range.
Future Conditions
The main factor influencing the viability of both Chipola slabshell
and fat threeridge is habitat degradation or loss through land use
change (e.g., urbanization, agriculture). Land use change can lead to
direct impacts on viability through increases in sedimentation and
contaminants within waters occupied by each mussel species. Predicting
future stream-channel conditions, particularly sedimentation, in the
ACF River Basin remains a challenge, as the ongoing remobilization of
sediments is difficult to separate from the cumulative effects of
climate and land-use change (Elliott et al. 2014, p. 66). An increase
in the contaminant load from incompatible land uses is expected to
continue in varying degrees, depending on a combination of factors
including the impacts of climate change across the landscape, with
habitat degradation or loss likely to be more significant in some MUs/
analysis units compared to others. We attempted to discern this
variance by analyzing spatially explicit models of future land use and
climate change as indicators of associated water quality and water
quantity conditions.
We identified the main drivers of change for the future scenario
analyses to be human population growth and subsequent urbanization and
land use change. Land use change may have synergistic effects with
climate change, so several common climate projections are considered in
the assessment of future condition. Species and ecosystems are impacted
by the habitat degradation and loss associated with population growth,
including impacts to water pollution, local climate conditions, and
disturbance dynamics.
Chipola Slabshell
Future conditions of the Chipola slabshell were assessed under
three plausible future scenarios (lower, moderate, and higher)
incorporating a range of conditions associated with climate and land
use change (Service 2020, pp. 96-125). The future scenarios were based,
in part, on the results of climate-informed land use change (USGS's
FOREcasting SCEnarios of Land-use Change (FORE-SCE)), with special
report emissions scenario (SRES) B1 for the lower range, SRES A1B for
moderate, and SRES A2 for the higher range, combined with
Intergovernmental Panel on Climate Change (IPCC) climate models, with
representative concentration pathway (RCP) 4.5 for the lower range, RCP
6.0 for moderate, and RCP 8.5 for higher range, that projected general
changes in habitat used by the Chipola slabshell. The factors that
influence resiliency in the species (e.g., occupancy, abundance,
sediment, canopy) either change minimally from the current condition
(lower range scenario) or worsen to a moderate (moderate range
scenario) or greater degree (higher range scenario) based on potential
future climate and land use and their impacts on water quality and
quantity. The expected future resiliency of each MU was forecasted
based on events that were projected to occur under each scenario
(Service 2020, pp. 208-133). All scenarios assumed that current
conservation efforts, which are in place regardless of listing status,
would remain in place but that no new actions would be taken. As with
current condition estimates, estimates were scaled up to MU and the
population levels (table 6, below).
The three scenarios project Chipola slabshell viability 20 and 40
years into the future, with each timestep representing approximately
two generations. This projection was chosen to represent a time frame
where climate change impacts may become apparent, while effects of
management actions can be implemented and realized on the landscape.
The 40-year timeframe, which includes approximately 4 to 5 generations,
is also reasonable for this relatively long-lived (15 to 20 years)
species, with relatively low fecundity, to respond to potential changes
on the landscape.
Table 6--Resiliency Summary for Chipola Slabshell MUs Including Current Condition, and Each of Three Future Scenarios (Lower, Moderate, Higher Range) at the End of the 40-Year Assessment
Period
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Current Lower range scenario Moderate range scenario Higher range scenario
Watershed (HUC- -----------------------------------------------------------------------------------------------------------------------------------------------
MU 10) Overall MU Overall MU Overall MU Overall MU
Watershed score resiliency Watershed score resiliency Watershed score resiliency Watershed score resiliency
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1............................. River Styx & High............ High............ High............ High............ High............ High............ Moderate........ Moderate.
Douglas Slough.
2............................. Merritts Mill Moderate........ Moderate........ Moderate........ Moderate........ Low............. Moderate........ Very Low........ Low.
Pond--South. Moderate........ High............ Moderate........ Moderate........
Mill Creek...... High............ High............ High............ High............
Tenmile Creek... Moderate........ Moderate........ Moderate........ Moderate........
Dead Lake.......
3............................. Marshall Creek.. Low............. Low............. Low............. Low............. Very Low........ Very Low........ Very Low........ Very Low.
Cowarts Creek... Moderate........ Moderate........ Very Low........ Very Low........
Merritts Mill Moderate........ Moderate........ Low............. Low.............
Pond--North.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
In the lower range scenario, we project no loss in MU resiliency
and redundancy compared to the current condition. Management units 1
and 2 would retain resiliency (in high or moderate resiliency), and MU
3 would remain at low resiliency. For this scenario, the Chipola
slabshell population is expected to persist in much the same condition
as it is found currently, with some increases in watershed resilience
through time given positive trends (e.g., future forest cover, recent
population expansions).
[[Page 85923]]
In the moderate range scenario, a loss of some resiliency and
redundancy is expected. Management units 1 and 2 retain resiliency, but
MU 3 may become extirpated given its overall very low resiliency. The
one watershed in MU 1 is expected to retain high resiliency. The
condition of MU 2 is expected to decrease slightly, with reduced
resiliency in one (of four) watersheds by 2060. Management unit 2 is
expected to retain more than one watershed with moderate or high
resiliency, while MU 3 is expected to retain only one occupied
watershed (Merritts Mill Pond--North), in low resiliency.
In the higher range scenario, we anticipate impacts to resiliency
in all management units. Management unit 1 has moderate resiliency with
a reduced capacity to mitigate stochastic events. Management units 2
and 3 exhibit reduced resiliency (low and very low, respectively), with
MU 3 likely extirpated. Management unit 2 retains resiliency in the
center of the Chipola slabshell range within the Mill Creek and Tenmile
Creek watersheds, with sparse to no observable presence in the Merritts
Mill Pond--South and Dead Lake watersheds. Similar to the moderate
range scenario, redundancy would be reduced to three watersheds with
likely extirpation in three of eight currently extant watersheds. Only
MU 2 retains more than one watershed with resiliency, and MU 3 retains
only one occupied watershed (Merritts Mill Pond--North) with low
resiliency.
The northern portion of the species range comprising the Chipola
River headwaters (MU 3) was the most susceptible to change through
time; MU 3 has low resiliency for current condition and is projected to
have very low resiliency under the higher range scenario. It is
important to note that the habitat in MU 3 is thought to be inherently
variable with regards to sedimentation and has overall low suitability
for Chipola slabshell. With the exception of small portions of MUs 1
and 3, almost the entirety of the Chipola slabshell population is
contained within the Chipola River mainstem in MU 2. Management unit 2
is projected to retain moderate resiliency to 2060 under the lower and
moderate range scenarios, but resiliency is reduced by 2060 under the
higher range scenario. Management unit 2 retains one watershed (Tenmile
Creek) at high resiliency through all scenarios and projection periods.
Management unit 1 is also projected to retain high to moderate
resiliency under all scenarios, benefitting from the presence of
extensive protected areas and more suitable large stream habitats for
Chipola slabshell.
Fat Threeridge
Based on our review of factors affecting viability of fat
threeridge, we focused our evaluation of future conditions on projected
habitat degradation associated with two prevalent land uses in the ACF
River Basin, agricultural and urban development, and their associated
stressors to water quality and quantity. We also assessed potential
impacts of SLR in lower portions of the Apalachicola and Chipola Rivers
through removal of suitable habitat from projected saltwater
inundation. We assessed resiliency, redundancy, and representation for
fat threeridge under three SLR threat levels (intermediate, high, and
extreme) and two multi-faceted scenarios incorporating variations in
future land and water use. We summarized changes in land use within
each of the fat threeridge analysis subwatersheds to assess future
changes in nonpoint source pollution. We assessed both the change in
the percent forested area in riparian buffers, and also the degree of
urbanization and agricultural land use within subwatersheds, similar to
what we assessed in current condition. To assess future water quantity,
we used the same modeling outputs as in current condition, which
provided annual predictions for the time frame 2045-2075. We extracted
results for two climate scenarios, RCP 4.5 and RCP 8.5, to bound
plausible future outcomes and compared these against a historical
simulated state (1950-2005). Annual inputs of both historical and
potential future land-cover type and percent impervious area were used
to incorporate the effects of changing vegetation and impervious area.
Scenario 1 assumes that conditions in the ACF River Basin continue
for the next 50 years along their current trajectory, with climate
change trajectories for SRES A2 and RCP 8.5 incorporated. Scenario 2
assumes that conditions in the ACF River Basin continue for the next 50
years along a modified trajectory, with climate change trajectories for
SRES B1 and RCP 4.5 incorporated. We analyzed these future threats and
their effects on habitat as indicators of directional change in
resiliency compared to the current condition (table 7, below). We
modeled threats 50 years into the future to project the conditions of
analysis units in 2070. This timeframe is biologically appropriate
(representing two or three generations) and within the available and
reliable modeling timeframe for projecting future threats. The 50-year
timeframe, which includes approximately 4 to 5 generations, is also
reasonable for this relatively long-lived (15 to 40 years) species,
with relatively low fecundity, to respond to potential changes on the
landscape. Timeframes earlier than 2070 may be too short to observe a
species response (based on a lifespan of at least 30 years) or change
in threats, and beyond 2070 were considered too far into the future to
reliably account for either. The land and water use threat assessment
was completed within the six analysis units.
Table 7--Summary of Fat Threeridge Current and Future Resiliency by Analysis Unit *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Future intermediate sea level rise Future high SLR \2\ Future extreme SLR \2\
Current (SLR) --------------------------------------------------------------------
Analysis unit resiliency ------------------------------------
Scenario 1 \1\ Scenario 2 Scenario 1 Scenario 2 Scenario 1 Scenario 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lower Flint.................. Mod............. Mod............. Mod............. Mod............. Mod............ Mod............ Mod.
Upper Apalachicola........... Mod............. Mod............. Mod............. Mod............. Mod............ Mod............ Mod.
Middle Apalachicola.......... High............ Mod............. High............ Mod............. High........... Mod............ High.
Lower Apalachicola........... High............ High............ High............ Low............. Low............ Low............ Low.
Lower Chipola................ High............ High............ High............ High............ High........... Low............ Low.
Chipola NDL.................. Mod............. Mod............. Mod............. Mod............. Mod............ Mod............ Mod.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Changes in water quality and quantity inform degree of habitat degradation for scenarios 1 and 2, while NOAA SLR projections (intermediate and high)
influence habitat removal by 2070.
\1\ Scenario 1 includes changes in water quality for the Middle Apalachicola that result in partial habitat degradation.
\2\ High and Extreme SLR involves partial removal of Lower Apalachicola.
[[Page 85924]]
Future habitat degradation associated with land use change is not
expected to impact fat threeridge significantly. No analysis units are
projected to become extirpated under any scenario, but one high
resiliency unit (Lower Apalachicola) may transition to low resiliency
in the future primarily due to SLR effects. Redundancy is maintained in
the future, regardless of scenario, as most (four of six) analysis
units retain moderate to high resiliency under the most severe
projections. Even under high SLR, fat threeridge is projected to
maintain representation in each river system (i.e., Apalachicola,
Chipola, and Flint) and in each ecoregion (i.e., Southeastern Plains
and Southern Coastal Plain).
By using the SSA framework to guide our analyses of scientific
information documented in the SSA reports, we have analyzed both
individual and cumulative effects on each species through
characterizing species condition currently and under various plausible
future scenarios. We assumed in our modeling of future conditions for
both species that increased habitat degradation could result from
increased land use or from climate change, or a combination. The
impacts of climate change, along with habitat degradation or loss, are
likely to be more significant in some MUs/analysis units than others,
however, our projections indicate that both species maintain
resiliency. Both species are projected to maintain a broad distribution
throughout the ACF River Basin, across a variety of habitats and under
both continuation and increased threat scenarios, meaning
representation and redundancy are not expected to change.
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA reports, we have
analyzed the cumulative effects of identified threats and conservation
actions on these species. To assess the current and future condition of
each 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.
Recovery Criteria
Section 4(f) of the Act directs us to develop and implement
recovery plans for the conservation and survival of endangered and
threatened species unless we determine that such a plan will not
promote the conservation of the species. Under section 4(f)(1)(B)(ii),
recovery plans must, to the maximum extent practicable, include
objective, measurable criteria which, when met, would result in a
determination, in accordance with the provisions of section 4 of the
Act, that the species be removed from the Lists of Endangered and
Threatened Wildlife and Plants.
Recovery plans provide a roadmap for us and our partners on methods
of enhancing conservation and minimizing threats to listed species, as
well as measurable criteria against which to evaluate progress towards
recovery and assess the species' likely future condition. However, they
are not regulatory documents and do not substitute for the
determinations and promulgation of regulations required under section
4(a)(1) of the Act. A decision to revise the status of a species or to
delist a species is ultimately based on an analysis of the best
scientific and commercial data available to determine whether a species
is no longer an endangered species or a threatened species, regardless
of whether that information differs from the recovery plan.
There are many paths to accomplishing recovery of a species, and
recovery may be achieved without all of the criteria in a recovery plan
being fully met. For example, one or more criteria may be exceeded
while other criteria may not yet be accomplished. In that instance, we
may determine that the threats are minimized sufficiently and that the
species is robust enough that it no longer meets the definition of an
endangered species or a threatened species. In other cases, we may
discover new recovery opportunities after having finalized the recovery
plan. Parties seeking to conserve the species may use these
opportunities instead of methods identified in the recovery plan.
Likewise, we may learn new information about the species after we
finalize the recovery plan. The new information may change the extent
to which existing criteria are appropriate for identifying recovery of
the species. The recovery of a species is a dynamic process requiring
adaptive management that may, or may not, follow all of the guidance
provided in a recovery plan.
In 2003, we published a recovery plan for seven mussel species,
including the Chipola slabshell and fat threeridge (Service 2003,
entire). In 2019, we amended the Chipola slabshell and fat threeridge
recovery plans to revise the recovery criteria and site-specific
recovery actions (Service 2019a, entire; Service 2019b, entire). Both
recovery plans for the Chipola slabshell and fat threeridge provide
three criteria for delisting.
Chipola Slabshell
For Chipola slabshell, the criteria to delist are: (1) the one
existing population must exhibit a stable or increasing trend, natural
recruitment, and multiple age classes; (2) the population from
criterion 1 occupies each of the three delineated units to protect
against extinction from catastrophic events and maintain adaptive
potential; and (3) threats are addressed and/or managed to the extent
that the species will remain viable into the foreseeable future.
Criterion 1
Criterion 1 states that the one existing population must exhibit a
stable or increasing trend, natural recruitment, and multiple age
classes. Currently, the Chipola slabshell is known from one panmictic
population within the Chipola River Basin. It is currently widespread
throughout its range and common at some localities. The comparison
between historical and current distribution shows an expansion north,
south, and east of the species' previously known range. Occupancy has
increased over time, although the magnitude of this estimate varies
with spatial scale. Prior to 1991, the Chipola slabshell occupied 46 km
(29 mi) in 6 U.S. Geological Survey (USGS) 10-digit hydrologic unit
codes (HUC-10s) watersheds, and its current range has expanded to
occupy 112 km (69 mi) in 7 HUC-10 watersheds. This increase in
occupancy suggests a robust distribution throughout the known range
(Service 2020, p. 62).
Our current condition resiliency analysis examined abundance and
reproduction across the range. Currently two HUC-10 watersheds have
excellent abundance and reproduction, four HUC-10 watersheds have good
abundance and reproduction, and two HUC-10 watersheds have fair
abundance and reproduction. While there are some portions of the range
with lower abundances and levels of recruitment, overall the Chipola
slabshell population has multiple age classes showing natural
recruitment, and the species has an expanded range. Thus, we conclude
that this criterion has been met for Chipola slabshell.
Criterion 2
Criterion 2 states the population (as identified in criterion 1)
occupies each of the three delineated units to protect against
extinction from catastrophic
[[Page 85925]]
events and maintain adaptive potential. All three delineated units, or
subpopulations, of Chipola slabshell are currently occupied, with two
of the three having moderate to high resiliency. Thus, we conclude that
this criterion has been met for Chipola slabshell.
Criterion 3
Criterion 3 for consideration of delisting Chipola slabshell states
that threats have been addressed or managed to the extent that the
species will remain viable into the foreseeable future. At the time of
listing, Chipola slabshell faced a variety of threats from declines in
water quality, loss of stream flow, riparian and instream
fragmentation, and deterioration of instream habitats. Additionally,
these threats were expected to be exacerbated by climate change and
urbanization.
Future water quantity models (updated every 5 years) in the Chipola
River Basin have projected adequate water supply for citizens and the
environment through 2045, even in drought years (NFWMD 2023, p. ix).
Water flows for most of the Chipola slabshell's occupied range are
protected through consumptive uses by water reservation (legal
protection), while other areas are supported by ground water
contributions from springs during drought (Service 2020, pp. 96-139).
Urbanization models have projected little growth in the river basin
through 2060 (Service 2020, pp. 27-60 and pp. 95-138).
During the most recent status review, there was no documentation of
any significant threats to the species or its habitat, as well as no
evidence that the species has experienced curtailment of range or
habitat, or is affected by disease or predation, commercial or
recreational harvest, the inadequacy of existing regulatory mechanisms,
or any other natural or manmade factor (Service 2020, p. 140). Thus, we
conclude that this criterion has been met for Chipola slabshell.
Fat Threeridge
For fat threeridge, the criteria to delist are: (1) at least four
populations exhibit a stable or increasing trend, evidenced by natural
recruitment and multiple age classes; (2) at last one population from
criterion 1 occupies each of the Flint and Chipola Rivers sub-basins,
and one population occupies two of the three delineated units in the
Apalachicola River sub-basin for fat threeridge; (3) threats have been
addressed or managed to the extent that each species will remain viable
into the foreseeable future (Service 2019a, pg. 4, and Service 2019b,
pg. 6).
Criterion 1
Criterion 1 states that at least four populations exhibit a stable
or increasing trend, evidenced by natural recruitment and multiple age
classes. Since the last 5-year review in 2007, our knowledge of fat
threeridge has increased substantially in all three river systems,
including what we know about distribution, habitat use, and life
history characteristics relevant to species recovery. As a result, we
now consider the fat threeridge to consist of one population, with six
analysis units. Further, we know that the species occupies most
watersheds where it was found historically, and our resiliency analysis
indicates that the species maintains moderate to high resiliency in the
six analysis units. One of the population factors for resiliency is
evidence of recruitment, and all six units exhibit recruitment through
observation of small size classes. Its range has expanded in the
Chipola and Apalachicola Rivers in Florida. Furthermore, fat threeridge
is more abundant and widely distributed among mesohabitats than
previously thought, including within deep habitats (Service 2021, pp.
54-55). Thus, fat threeridge has stable trends in all six units, and
high levels of recruitment, with an overall indication that multiple
age classes exist in each unit throughout the population. For these
reasons, we conclude that fat threeridge has met this criterion.
Criterion 2
Criterion 2 for consideration of delisting fat threeridge states
that at least one population occupies each of the Flint and Chipola
Rivers sub-basins and in the Apalachicola River sub-basin at least one
population occupies two of the three delineated units (Service 2019b,
p. 6). As described in the SSA report, there are six subpopulations
(also referred to as analysis units): one in the Flint, three in the
Apalachicola, and two in the Chipola Rivers sub-basins (Service 2021,
p. 52). Resiliency is moderate in the Lower Flint, Upper Apalachicola,
and Chipola North of Dead Lakes analysis units; it is high in the
Middle Apalachicola, Lower Apalachicola, and Lower Chipola analysis
units (Service 2021, p. 69). Based on this, we conclude that criterion
2 has been met for fat threeridge.
Criterion 3
Criterion 3 for consideration of delisting fat threeridge states
that threats have been addressed or managed to the extent that the
species will remain viable into the foreseeable future. The primary
threats to fat threeridge include land use change resulting in reduced
water quality and quantity, and effects associated with climate change,
including sea level rise (SLR). Our future conditions analysis
indicates that at the watershed scale, the amount of land development
through 2070 is projected to be low across all scenarios (Service 2021,
pp. 115-116). No analysis units are expected to become extirpated, but
two high resiliency units (Lower Apalachicola, Lower Chipola) may
transition to low resiliency in the future as a result of SLR effects
as projected in the high SLR scenarios (Service 2021, p.127).
Redundancy is maintained under future scenarios, as most (four of
six) analysis units retain resiliency under the most severe
projections, and no change from the current condition is expected under
intermediate SLR. Even under extreme SLR, ecoregion and river
representation for fat threeridge is maintained.
Increased sampling efforts and a better understanding of the
species' habitat associations indicate a wider distribution of the fat
threeridge than previously understood. In general, fat threeridge is
more abundant and widely distributed among habitats than previously
thought. Habitat mapping and species distribution modeling in the
Apalachicola and Lower Chipola Rivers indicates sufficient abundance of
habitat for the fat threeridge in these populations; similar habitat
mapping has not been done at that scale for the Flint River, but
habitat for the population at Newton, Georgia has supported the fat
threeridge since 2006 (Service 2021, pp. 41-50). For these reasons, we
conclude that this criterion has been met for fat threeridge.
Determinations of Chipola Slabshell and Fat Threeridge 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 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 a species meets the definition of an
endangered species or a threatened
[[Page 85926]]
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 Their Range
After evaluating the threats to these species and assessing the
cumulative effects of the threats under the Act's section 4(a)(1)
factors, we find that both the Chipola slabshell and fat threeridge
have expanded distributions with nearly all populations having moderate
to high resiliency and projections to maintain resiliency into the
future. The primary threat at the time of listing was habitat loss and
destruction. Based on our analyses of the current and future condition
for the Chipola slabshell and fat threeridge, each species currently
has sufficient resiliency and is projected to maintain resiliency into
the future such that each species can withstand stochastic and
catastrophic effects from existing and future threats. Together the
current and future conditions analyses informed our determination as to
whether each species is in danger of extinction throughout all of its
range (i.e., whether each species meets the definition of an endangered
species under the Act) or whether each species is in danger of
extinction throughout all of its range in the foreseeable future (i.e.,
whether each species meets the definition of a threatened species under
the Act). Our determinations for each species are discussed below.
Chipola Slabshell--Status Throughout All of Its Range
The Chipola slabshell is currently widespread throughout its range
and considered common at some localities. Since the time of listing,
surveys indicate expansion of its previously known range. Two-thirds of
the range have moderate to high resiliency, and the one MU, or sub-
population, that has low resiliency (MU 3) has a high proportion of
marginal habitat for the species, and naturally low numbers of Chipola
slabshell. Despite this, occupancy is good to excellent throughout the
range. To summarize the species' current condition, the Chipola
slabshell has sufficient resiliency to withstand stochastic events, as
well as sufficient redundancy in the distribution of subpopulations
with moderate to high resiliency such that the species can withstand
catastrophic events.
Potential threats to the species, including habitat degradation
which led to the species being listed, appear to be well managed or
minimized to the greatest extent possible either through protection,
implementation of BMPs, and regulations in CWA or State OFW
designations. Sedimentation, which is usually a major threat for mussel
species, is not a current threat to Chipola slabshell in the Chipola
River Basin. Thus, after assessing the best available information, we
determine that Chipola slabshell is not in danger of extinction
throughout all of its range.
We next evaluate whether the Chipola slabshell is likely to be in
danger of extinction throughout its range within the foreseeable
future. We considered climate change and land use change as primary
stressors influencing habitat degradation and loss, and we developed
three scenarios that project Chipola slabshell viability 40 years into
the future. This 40-year foreseeable future includes a time frame where
both climate change and land use change effects will become apparent on
the landscape. The timeframe also includes up to five generations which
we consider reasonable for this relatively long-lived (15 to 20 years),
low fecundity species to respond to potential changes on the landscape.
We are able to reliably predict both the threats to the species and the
species' response to those threats within this timeframe.
Almost the entirety of the Chipola slabshell population is
contained within the Chipola River mainstem. The core of the population
(MU 2) is projected to retain moderate resiliency to 2060 under the
Lower and Moderate Range Scenarios, but resiliency could be reduced by
2060 under the higher range scenario. Despite this, two thirds of the
watersheds that make up MU 2 retain moderate to high resiliency through
all scenarios and projection periods. In addition, MU 1 is also
projected to retain moderate to high resiliency under all scenarios,
benefitting from the presence of extensive protected areas and
available suitable large stream habitats for Chipola slabshell. Thus,
species' viability is sustained within two of the three MUs into the
future. The species' ability to retain resiliency 40 years into the
future supports the determination that the Chipola slabshell is not in
danger of extinction throughout all of its range in the foreseeable
future.
Thus, after assessing the best available information, we conclude
that Chipola slabshell is not in danger of extinction now or likely to
become so in the foreseeable future throughout all of its range.
Chipola Slabshell--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. Having determined that the Chipola slabshell is not in
danger of extinction or likely to become so in the foreseeable future
throughout all of its range, we now consider whether it may be in
danger of extinction (i.e., endangered) or likely to become so in the
foreseeable future (i.e., threatened) 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 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.
In undertaking this analysis for the Chipola slabshell, we choose
to address the status question first. We began by identifying portions
of the range where the biological status of the species may be
different from its biological status elsewhere in its range. For this
purpose, we considered information pertaining to the geographic
distribution of (a) individuals of the species, (b) the threats that
the species faces, and (c) the resiliency condition of populations.
We evaluated the range of the Chipola slabshell to determine if the
species is in danger of extinction now or likely to become so in the
foreseeable future 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 or a threatened
species. For the Chipola slabshell, 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 now or likely to become so
in the foreseeable future in that portion.
The Chipola slabshell is found solely in the ACF River Basin, which
extends approximately 620 km (385 mi). This
[[Page 85927]]
species is a narrow endemic functioning as single, contiguous
population and the MUs used do not represent biological populations,
rather they were delineated as analysis units. However, these MUs could
be considered portions, and one MU (MU 3) may represent a portion of
the range that could have a different status. Management unit 3,
comprised of marginal habitat and located in the Chipola River
headwaters, currently has low resiliency and could possibly become
extirpated (projected to have very low resiliency) in the foreseeable
future. Thus, this could be a portion of the range that may be in
danger of extinction now or within the foreseeable future. Having
answered the status question affirmatively for MU 3, we then considered
whether this unit is significant.
To assess whether MU 3 is significant, we considered whether the
area occupies a relatively large or particularly high-quality or unique
habitat. Management unit 3 is not large, as it comprises less than one
third of the known range of the species. We also examined whether the
unit or characteristics within the unit make the species less
susceptible to certain threats than other portions of the species'
range, such that it could provide important population refugia in the
event of extirpations elsewhere in the species' range. Although MU 3
contributes to the overall species-level representation and redundancy,
it does not contain high quality nor high value habitat or any habitat
or resources unique to that area. For these reasons, we do not find
this portion to be significant. Therefore, this unit does not represent
a significant portion of the range, and we find that the species is not
in danger of extinction now or likely to become so in the foreseeable
future in any significant portion of its range. This does not conflict
with the courts' holdings in Desert Survivors v. 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 on Interpretation of the Phrase
``Significant Portion of Its Range'' in the Endangered Species Act's
Definitions of ``Endangered Species'' and ``Threatened Species'' (79 FR
37578; July 1, 2014), including the definition of ``significant'' that
those court decisions held to be invalid.
Determination of Status--Chipola Slabshell
Our review of the best scientific and commercial data available
indicates that the Chipola slabshell does not meet the definition of an
endangered species or a threatened species in accordance with sections
3(6) and 3(20) of the Act. In accordance with our regulations at 50 CFR
424.11(e)(2) currently in effect, the species has recovered to the
point at which it no longer meets the definition of an endangered
species or a threatened species. Therefore, we propose to remove the
Chipola slabshell from the Federal List of Endangered and Threatened
Wildlife.
Fat Threeridge--Status Throughout All of Its Range
Fat threeridge is more abundant and widely distributed than
previously thought. Current positive trends for both population and
habitat factors, including relatively large population sizes with
evidence of recruitment, are indicative of populations that are
resilient to stochastic factors. All six analysis units across the
species range exhibit moderate to high resiliency. The distribution of
each resilient unit contributes to the species' ability to withstand
catastrophic events. Further, the species has not experienced a change
in connectivity--such as an impoundment--within its range, which is
what generally corresponds to a lowered risk of extirpation from
catastrophic events. For these reasons, we determined that the fat
threeridge is not currently in danger of extinction throughout its
range.
We then considered whether the species may be likely to become in
danger of extinction within the foreseeable future throughout its
range. We considered threats 50 years into the future to project the
conditions of the six analysis units to 2070. For fat threeridge, this
timeframe is biologically appropriate (representing two or three
generations) and within the available and reliable modeling timeframe
for projecting future water quality and quantity, threats of
urbanization and SLR. Timeframes earlier than 2070 were considered too
short to observe a species response (based on a lifespan of at least 30
years) or noticeable change in threats, and beyond 2070 were considered
too far into the future to reliably account for species response.
Future water quality and quantity degradation associated with land
use change is not expected to impact fat threeridge. Over the 50-year
timeframe, no analysis units are projected to become extirpated. Two
currently high resiliency units (Lower Apalachicola, Lower Chipola) may
transition to low resiliency in the future under the most extreme SLR
effects. Species' redundancy is maintained in the future, regardless of
scenario, as most (four of six) analysis units retain moderate to high
resiliency under the most severe projections. Even under extreme SLR,
fat threeridge is projected to maintain moderate to high resiliency in
all but one analysis unit, thus representation is projected to be
maintained in each river system (i.e., Apalachicola, Chipola, and Flint
Rivers) and in each ecoregion (i.e., Southeastern Plains and Southern
Coastal Plain). For these reasons, we conclude that the fat threeridge
is not in danger of extinction now or likely to become so in the
foreseeable future throughout all of its range.
Fat Threeridge--Status Throughout a Significant Portion of Range
In undertaking this analysis for fat threeridge, we choose to
address the status question first. We began by identifying portions of
the range where the biological status of the species may be different
from its biological status elsewhere in its range. For this purpose, we
considered information pertaining to the geographic distribution of (a)
individuals of the species, (b) the threats that the species faces, and
(c) the resiliency condition of populations.
We evaluated the range of the fat threeridge to determine if the
species is in danger of extinction now or likely to become so in the
foreseeable future 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 or a threatened
species. For fat threeridge, 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 now or likely to become so in the
foreseeable future in that portion.
The fat threeridge is found solely in the ACF River Basin, which
extends approximately 620 km (385 mi). This species is a single,
contiguous population and the units delineated for our analysis do not
represent biological populations. We determined that two units
together, representing the lower portion of the species' range (Lower
Apalachicola and Lower Chipola) are a portion of the range that may
have a different status due to effects related to SLR. Current
resiliency for this portion is high, therefore the fat threeridge is
not in danger of extinction now in this portion of the range, but
future projections indicate that this portion could change from high
resiliency to low resiliency under the high and extreme SLR scenarios
within the
[[Page 85928]]
foreseeable future. Thus, we considered this a portion of the range
that could become in danger of extinction in the foreseeable future.
We next considered whether this portion constitutes a significant
portion of the fat threeridge's range. To assess its significance, we
evaluated whether the area is relatively large or particularly high-
quality, unique habitat. We also examined whether the characteristics
within the lower portion of the range make the species less susceptible
to certain threats than other portions of the species' range, such that
it could provide important population refugia in the event of
extirpations elsewhere in the species' range. The Lower Apalachicola
and Lower Chipola do not constitute a large geographic area (less than
20 percent of range) nor do they contain habitat of high quality
relative to the rest of the range. This portion also does not
constitute habitat or resources unique to that area for the species, as
similar habitat is found throughout the range. For these reasons, we do
not find this portion to be significant. Therefore, the lower portion
of the fat threeridge range does not represent a significant portion of
the range, and we find that the species is not in danger of extinction
now or likely to become so in the foreseeable future in any significant
portion of its range. This does not conflict with the courts' holdings
in Desert Survivors v. 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 on
Interpretation of the Phrase ``Significant Portion of Its Range'' in
the Endangered Species Act's Definitions of ``Endangered Species'' and
``Threatened Species'' (79 FR 37578; July 1, 2014), including the
definition of ``significant'' that those court decisions held to be
invalid.
Determination of Status--Fat Threeridge
Our review of the best scientific and commercial data available
indicates that the fat threeridge does not meet the definition of an
endangered species or a threatened species in accordance with sections
3(6) and 3(20) of the Act. In accordance with our regulations at 50 CFR
424.11(e)(2) currently in effect, the species has recovered to the
point at which it no longer meets the definition of an endangered
species or a threatened species. Therefore, we propose to remove the
fat threeridge from the Federal List of Endangered and Threatened
Wildlife.
Effects of This Rule
This proposed rule, if made final, would revise 50 CFR 17.11(h) by
removing both the Chipola slabshell mussel (Elliptio chipolaensis) and
the fat threeridge mussel (Amblema neislerii) from the Federal List of
Endangered and Threatened Wildlife. The prohibitions and conservation
measures provided by the Act, particularly through sections 7 and 9,
would no longer apply to these species. Federal agencies would no
longer be required to consult with the Service under section 7 of the
Act in the event that activities they authorize, fund, or carry out may
affect these species.
Critical habitat for Chipola slabshell and fat threeridge at 50 CFR
17.95(f) would be removed if this proposal is made final.
Post-Delisting Monitoring
Section 4(g)(1) of the Act requires us, in cooperation with the
States, to implement a monitoring program for not less than 5 years for
all species that have been recovered. Post-delisting monitoring (PDM)
refers to activities undertaken to verify that a species delisted due
to recovery remains secure from the risk of extinction after the
protections of the Act no longer apply. The primary goal of PDM is to
monitor the species to ensure that its status does not deteriorate, and
if a decline is detected, to take measures to halt the decline so that
proposing it as endangered or threatened is not again needed. If at any
time during the monitoring period data indicate that protective status
under the Act should be reinstated, we can initiate listing procedures,
including, if appropriate, emergency listing.
We will coordinate with other Federal agencies, State resource
agencies, interested scientific organizations, and others as
appropriate to develop and implement effective PDM plans for the
Chipola slabshell and fat threeridge. The PDM plans will build upon
current research and effective management practices that have improved
the status of each of the species since listing. Ensuring continued
implementation of proven management strategies that have been developed
to sustain each of the species will be a fundamental goal for the PDM
plans. The PDM plans will identify measurable management thresholds and
responses for detecting and reacting to significant changes in Chipola
slabshell and fat threeridge numbers, distribution, and persistence. If
declines are detected equaling or exceeding these thresholds, the
Service, in combination with other PDM participants, will investigate
causes of these declines. The investigation will be to determine if the
Chipola slabshell or fat threeridge warrants expanded monitoring,
additional research, additional habitat protection, or resumption of
Federal protection under the Act.
We appreciate any information on what should be included in post-
delisting monitoring strategies for these species (see Information
Requested, above).
Required Determinations
Clarity of the Rule
We are required by Executive Orders 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 rule, 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.
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), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with federally recognized
Tribes on a government-to-government basis. In accordance with
Secretarial 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.
[[Page 85929]]
There are no Tribal lands associated with this proposed rule.
References Cited
A complete list of references cited in this rulemaking is available
on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> and upon request from
the Florida Ecological Services 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 Florida
Ecological Services 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
0
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.
Sec. 17.11 [Amended]
0
2. In Sec. 17.11, amend paragraph (h) by removing the entries for
``Slabshell, Chipola'' and ``Threeridge, fat'' under CLAMS from the
List of Endangered and Threatened Wildlife.
0
3. In Sec. 17.95, in paragraph (f), amend the entry for ``Seven mussel
species (in four northeast Gulf of Mexico drainages): Purple
bankclimber (Elliptoideus sloatianus), Gulf moccasinshell (Medionidus
penicillatus), Ochlockonee moccasinshell (Medionidus simpsonianus),
oval pigtoe (Pleurobema pyriforme), shinyrayed pocketbook (Hamiota
subangulata), Chipola slabshell (Elliptio chipolaensis), and fat
threeridge (Amblema neislerii)'' by revising the entry's heading, the
introductory text of paragraph (2), paragraph (5), the table in
paragraph (6), the introductory text of paragraph (8), paragraph
(8)(ii), the introductory text of paragraph (13), paragraph (13)(ii),
the introductory text of paragraph (14), and paragraph (14)(ii) to read
as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(f) Clams and Snails.
* * * * *
Five mussel species (in four northeast Gulf of Mexico drainages):
Purple bankclimber (Elliptoideus sloatianus), Gulf moccasinshell
(Medionidus penicillatus), Ochlockonee moccasinshell (Medionidus
simpsonianus), oval pigtoe (Pleurobema pyriforme), and shinyrayed
pocketbook (Hamiota subangulata)
* * * * *
(2) The primary constituent elements of critical habitat for the
purple bankclimber (Elliptoideus sloatianus), Gulf moccasinshell
(Medionidus penicillatus), Ochlockonee moccasinshell (Medionidus
simpsonianus), oval pigtoe (Pleurobema pyriforme), and shinyrayed
pocketbook (Hamiota subangulata), are:
* * * * *
(5) Index map of critical habitat units in the States of Alabama,
Florida, and Georgia for the five mussels follows:
Figure 1 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
shinyrayed pocketbook (Hamiota subangulata) Paragraph (5)
[[Page 85930]]
[GRAPHIC] [TIFF OMITTED] TP29OC24.001
(6) * * *
Table 1 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
shinyrayed pocketbook (Hamiota subangulata) Paragraph (6)
------------------------------------------------------------------------
Critical habitat
Species units States
------------------------------------------------------------------------
Purple bankclimber (Elliptoideus Units 5, 6, 7, 8, AL, FL, GA.
sloatianus). 9, 10.
Gulf moccasinshell (Medionidus Units 1, 2, 4, 5, AL, FL, GA.
penicillatus). 6, 7.
Ochlockonee moccasinshell Unit 9............ FL, GA.
(Medionidus simpsonianus).
Oval pigtoe (Pleurobema Units 1, 2, 4, 5, AL, FL, GA.
pyriforme). 6, 7, 9, 11.
Shinyrayed pocketbook (Hamiota Units 2, 3, 4, 5, AL, FL, GA.
subangulata). 6, 7, 9.
------------------------------------------------------------------------
[[Page 85931]]
* * * * *
(8) Unit 2. Chipola River and Dry, Rocky, Waddells Mill, Baker,
Marshall, Big, and Cowarts Creeks in Houston County, Alabama, and in
Calhoun, Gulf, and Jackson Counties, Florida. This is a critical
habitat unit for the shinyrayed pocketbook, Gulf moccasinshell, and
oval pigtoe.
* * * * *
(ii) Unit 2 map follows:
Figure 3 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
shinyrayed pocketbook (Hamiota subangulata) Paragraph (8)(ii)
[GRAPHIC] [TIFF OMITTED] TP29OC24.002
* * * * *
(13) Unit 7. Lower Flint River and Spring, Aycocks, Dry,
Ichawaynochaway, Mill, Pachitla, Little Pachitla, Chickasawhatchee, and
Cooleewahee creeks in Baker, Calhoun, Decatur, Dougherty, Early,
Miller, Mitchell, and Terrell Counties, Georgia. This is a critical
habitat unit for the
[[Page 85932]]
shinyrayed pocketbook, Gulf moccasinshell, oval pigtoe, and purple
bankclimber.
* * * * *
(ii) Two maps of Unit 7--western part of unit 7 and eastern part of
unit 7--follow:
Figure 10 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
shinyrayed pocketbook (Hamiota subangulata) Paragraph (13)(ii)
[GRAPHIC] [TIFF OMITTED] TP29OC24.003
Figure 11 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
[[Page 85933]]
shinyrayed pocketbook (Hamiota subangulata) Paragraph (13)(ii)
[GRAPHIC] [TIFF OMITTED] TP29OC24.004
(14) Unit 8. Apalachicola River, Chipola Cutoff, Swift Slough,
River Styx, Kennedy Slough, and Kennedy Creek in Calhoun, Franklin,
Gadsden, Gulf, Jackson, and Liberty Counties, Florida. This is a
critical habitat unit for the purple bankclimber.
* * * * *
(ii) Unit 8 map follows:
Figure 12 to Five mussel species (in four northeast Gulf of Mexico
drainages): Purple bankclimber (Elliptoideus sloatianus), Gulf
moccasinshell (Medionidus penicillatus), Ochlockonee moccasinshell
(Medionidus simpsonianus), oval pigtoe (Pleurobema pyriforme), and
shinyrayed pocketbook (Hamiota subangulata) Paragraph (14)(ii)
[[Page 85934]]
[GRAPHIC] [TIFF OMITTED] TP29OC24.005
* * * * *
Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2024-23929 Filed 10-28-24; 8:45 am]
BILLING CODE 4333-15-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on October 29, 2024.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.