Proposed Listing and Critical Habitat of Southern Elktoe Frequently Asked Questions

1. What action is the U.S. Fish and Wildlife Service taking? 

We are proposing to list the southern elktoe (Alasmidonta triangulata), a freshwater mussel species endemic to the Apalachicola-Chattahoochee-Flint Basin of Alabama, Georgia, and Florida, as an endangered species. We are also proposing to designate 578 river miles in 25 counties as critical habitat. 

2. Why is the Service proposing to list the southern elktoe? 

On April 20, 2010, the southern elktoe was included in the petition to list 404 aquatic species in the southeastern United States. We completed a partial 90-day finding on September 27, 2011, announcing our finding that the petition contained substantial information that listing may be warranted for numerous species, including the southern elktoe. After a review of the best available scientific and commercial information, the Service finds that the species meets the definition of an endangered species under the Endangered Species Act (ESA), meaning that it is currently in danger of extinction.  

3. What is the southern elktoe, and where can it be found? 

The southern elktoe is a medium sized freshwater mussel that reaches up to 2.8 inches in length. It is endemic to the Apalachicola, Chattahoochee, and Flint River (ACF) basins of Alabama, Florida, and Georgia. Although recent surveys since 2000 have documented the species as still occurring in all four large river basins of the ACF Basin (Apalachicola River, Chipola River, Chattahoochee River, and the Flint River), the southern elktoe is considered very rare in distribution during both historical and current (since 2000) time frames. The species can be found along stream edges where flows are often slow, but steady, and in substrates that are a mixture of silty mud, sand, and gravel. Unlike many other freshwater mussel species that occur in dense "mussel beds," the southern elktoe is most often found in low numbers. 

4. What habitat elements does the species need to survive? 

The southern elktoe needs streams that are permanently flowing (i.e., without dams or other structures that impede flow) and have bottoms that are stable and not frequently changing. All freshwater mussels have several key life stages:  a fertilized egg, glochidia (a baby mussel that attaches to a host fish), juvenile (once glochidia have dropped from the host fish and are free-living), and an adult. Each one of these life stages is unique and has specific resource requirements. The general requirements for all life stages of the southern elktoe are flowing waters with good water quality, and temperatures and dissolved oxygen levels within the species’ tolerance limits. For reproduction, adult males and females need to be close in proximity to allow fertilization, and the host fish species must occur in the nearby vicinity for glochidia to attach. All mussels have specific host fish species and for the southern elktoe, it is members of the sucker fish family.  

5. What is the difference between endangered and threatened under the ESA? 

The ESA describes two categories of declining species that warrant federal protections – “endangered” and “threatened”– and provides these definitions:  

Endangered – any species that is in danger of extinction throughout all or a significant portion of its range. 

Threatened – any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.  

In simple terms, endangered species are in danger of extinction now; threatened species are likely to become in danger of extinction in the foreseeable future. Therefore, the definition of each term hinges on the time element, now versus the future. 

6. What are the primary threats of the southern elktoe? 

We found that past and ongoing habitat degradation and loss, including impaired water quality, decreased water quantity and barriers to host fish movement, have reduced habitat suitability for the southern elktoe to such a degree that there is little to no resiliency of the species throughout its range. Currently, the southern elktoe is restricted to larger rivers and mainstream habitats within the ACF Basin, which represents significantly reduced distribution from historical conditions. 

7. What critical habitat are you proposing, and does it overlap with critical habitat for any other listed species? 

We are proposing five units as critical habitat for the southern elktoe. We are proposing to designate approximately 577.6 river miles (929.5 river km) in five units as critical habitat for the southern elktoe (Table 1). The critical habitat areas we describe below constitute our current best assessment of areas that meet the definition of critical habitat for the species. The five units we propose as critical habitat are: (1) Apalachicola River, (2) Chipola River, (3) Lower Flint River Complex, (4) Upper Flint River Complex, and (5) Middle Chattahoochee. 

TABLE 1 - Proposed critical habitat units for southern elktoe. 

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

Critical Habitat Unit 

Land Ownership by Type 

Length of Unit in River Kilometers (Miles) 


1. Apalachicola River 

Public and Private 

142.8 (88.7) 


2. Chipola River 

Public and Private 

131.3 (81.6) 


3. Lower Flint River Complex 

Public and Private 

165.9 (103.1) 


4. Upper Flint River Complex 

     4a: Patsiliga Creek 

     4b: Upper Flint Tributaries 

Public and Private 

Total: 396.6 (246.4) 

36.2 (22.5) 

360.4 (223.9) 



5. Middle Chattahoochee 

     5a: Uchee Creek 

     5b: Little Uchee Creek 

     5c: Mulberry Creek 

Public and Private 

Total: 92.9 (57.7) 

36.7 (22.8) 

20.3 (12.6) 

35.9 (22.3) 





929.5 (577.6) 

The proposed critical habitat designation includes rivers and streams within the current range that we determined to be critical to the conservation of these species and which were occupied by the species at the time of listing.  These rivers and streams contain known populations, some of which will likely be self-sustaining over time, and have retained the physical or biological features that could allow for the maintenance and expansion of existing populations. 

We also are proposing to designate specific areas outside the area currently occupied by the species because we have determined that a designation limited to occupied areas would be inadequate to ensure the conservation of the species.  There are current records of southern elktoe in the Upper Flint River Complex and the Middle Chattahoochee system; however, the currently occupied reaches are significantly reduced compared to historical distribution.   

Conservation efforts for other listed species and other existing critical habitat designations are likely to provide conservation benefits to the southern elktoe.  Listed species that co-occur with the southern elktoe include the fat purple bankclimber, Gulf sturgeon, shinyrayed pocketbook, oval pigtoe, Chipola slabshell, and Gulf moccasinshell.  Approximately 79% of the proposed critical habitat designation for the southern elktoe overlaps with existing critical habitat for these other species. 

Table 2 - Unit and co-occurring ESA-listed species or existing critical habitats within the range of the southern elktoe. 

Critical Habitat Unit 

Co-occurring Listed Species and/or Existing Critical Habitat for Other Listed Species? 

Approximate Area of Overlap  (mi) 

Does species have overlapping conservation requirements with subject species? 

Unit 1 

fat threeridge, purple bankclimber, Gulf sturgeon 

Entire unit 


Unit 2 

fat threeridge, Chipola slabshell, shinyrayed pocketbook, Gulf moccasinshell, oval pigtoe 

Entire unit 


Unit 3 

fat threeridge, purple bankclimber, shinyrayed pocketbook, Gulf moccasinshell, oval pigtoe 

Partial  (98.8) 


Subunit 4a 

Subunit 4b 


purple bankclimber, shinyrayed pocketbook, Gulf moccasinshell, oval pigtoe 


Partial  (165.9) 



Subunit 5a 

Subunit 5b 

Subunit 5c 

shinyrayed pocketbook 

shinyrayed pocketbook, Gulf moccasinshell 

shinyrayed pocketbook, Gulf moccasinshell 

shinyrayed pocketbook, Gulf moccasinshell 

Partial (19.5) 






8. What is critical habitat? 

The Service has the authority to identify critical habitat when it proposes to list an animal or plant as endangered or threatened.  Critical habitat is identified based on what an animal or plant needs to survive and reproduce by reviewing the best scientific information concerning a species’ present and historical ranges, habitat, and biology. 

The designation of critical habitat helps ensure federal agencies and the public are aware of the habitat needs of the southern elktoe and proper consultation is conducted by federal agencies when required by law.   

The designation will have no impact on private landowners taking actions on their land that do not require federal funding or permits. 

9. What does critical habitat do? 

When an area is designated as critical habitat for a listed species, federal agencies are required to ensure that any action they fund, authorize or carry out is not likely to result in the destruction of the habitat.  This is carried out through consultation with the Service under Section 7 Section 7
Section 7 Consultation The Endangered Species Act (ESA) directs all Federal agencies to work to conserve endangered and threatened species and to use their authorities to further the purposes of the Act. Section 7 of the Act, called "Interagency Cooperation," is the mechanism by which Federal agencies ensure the actions they take, including those they fund or authorize, do not jeopardize the existence of any listed species.

Learn more about Section 7
of the ESA.  This only affects projects that require a federal permit or other actions funded or conducted by a federal agency.  

   The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area conservation area
A conservation area or wildlife management area is a type of national wildlife refuge that consists primarily or entirely of conservation easements on private lands. These conservation easements support private landowner efforts to protect important habitat for fish and wildlife. There are 13 conservation areas and nine wildlife management areas in the National Wildlife Refuge System.

Learn more about conservation area
.  A critical habitat designation also does not allow the government or public to access private lands, nor does it require implementation of restoration, recovery, or enhancement measures by non-federal landowners.  

10. How can I submit my comments? 

The public is invited to submit written comments on the proposal to list the southern elktoe and designate critical habitat up to 60 days from its June 20, 2023 publication in the Federal Register.  Please submit comments by August 21, 2023.  The Service will post all comments on  This generally means the agency will post any personal information provided through the process.    

All relevant information received during the open comment period from the public, government agencies, the scientific community, industry, or any other interested parties will be considered and addressed in the Service’s final listing determination and critical habitat designation for the southern elktoe.    

The complete listing proposal can be obtained by visiting the Federal eRulemaking Portal: at Docket Number FWS–R4–ES–2022-0179    

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