Frequently Asked Questions
What is the sickle darter? 

The sickle darter is a small, semi-pelagic fish (found both on the bottom and in the water column) native to the upper Tennessee River drainage in North Carolina, Tennessee and Virginia. Sickle darters are typically found in slow flowing pools of larger, upland creeks and small to medium rivers.   

Where does the sickle darter occur?   

Historically (prior to 2005), the sickle darter was known from nine tributary systems of the upper Tennessee River drainage in the following rivers in North Carolina, Tennessee and Virginia: Emory, Clinch, Powell, Little, French Broad, North Fork Holston, Middle Fork Holston, South Fork Holston and Watauga. Currently, it is represented by six populations occupying portions of the Emory River system (Tennessee), the Upper Clinch River system (Virginia), the Little River system (Tennessee), the North Fork Holston River system (Virginia), the Middle Fork Holston River system (Virginia), and the Sequatchie River system (Tennessee – discovered in 2014). Populations within the French Broad River (North Carolina), South Fork Holston River (Tennessee), Powell River (Tennessee), and Watauga River systems (Tennessee) have been lost.  

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

The U.S. Fish and Wildlife Service is proposing to designate 104 river miles (rmi) in six units in Tennessee and Virginia as critical habitat for the sickle darter. The Service is also announcing the availability of a draft economic analysis (DEA) of the proposed critical habitat designation. 

What are the threats to the sickle darter?  

Habitat loss and degradation resulting from impoundments, siltation (excess sediment in streams), and water quality degradation (pollution) is the principal threat to the sickle darter. Agriculture, development, and resource extraction (e.g., mining) are some of the main sources of siltation and pollution in species’ range. These threats, combined with the negative effects of the species’ reduced range, have caused the disappearance of sickle darter populations in the French Broad River, South Fork Holston River, Powell River and Watauga River systems, prompting the Service to propose listing the species as threatened under the Endangered Species Act (ESA) in November 2020. The species’ only population within the Blue Ridge ecoregion of North Carolina (French Broad River system) has been eliminated. 

How does the ESA define critical habitat? 

The ESA defines critical habitat as the specific geographic areas that contain features essential to the conservation of an endangered or threatened species that may require special management and protection. Critical habitat may also include areas that are not currently occupied by the species but will be needed for its recovery. 

How does the Service determine what areas to designate as critical habitat? 

Within areas occupied by the species, biologists consider physical or biological features needed for life processes. These include: 

  • Space for individual and population growth and for normal behavior;  

  • Cover or shelter; 

  • Food, water, air, light, minerals, or other nutritional or physiological requirements; 

  • Sites for breeding and rearing offspring; and 

  • Habitats that are protected from disturbances or are representative of the historical, geographical, and ecological distributions of a species. 

After considering occupied areas, biologists consider unoccupied areas that may be essential for the conservation of the species. 

What is the proposed critical habitat for the sickle darter? 

In total, approximately 104 rmi in six units in Bledsoe, Blount, Morgan, and Roane counties, Tennessee, and Scott, Smyth, and Washington counties, Virginia, are included in the proposed critical habitat designation. All six units of proposed critical habitat for the sickle darter consists entirely of occupied habitat. Coordinates and plot points for the proposed critical habitat can be downloaded from the Service’s website: 

The areas proposed for critical habitat include lands under Federal (1 percent), State (6 percent), and private (93 percent) ownership. There are no lands under Tribal ownership in the proposed designation. Twenty-three listed aquatic species co-occur with the sickle darter in the proposed critical habitat and the proposed units overlap with designated critical habitat for nine of these species: the spotfin chub, yellowfin madtom, Cumberlandian combshell, fluted kidneyshell, oyster mussel, purple bean, rough rabbitsfoot, and slabside pearlymussel. Overlapping critical habitat includes 83 rmi (80 percent) of the proposed critical habitat. 

What is the draft economic analysis on this proposed action and why was it done?  What did it find? 

Draft economic analyses (DEA) are created to analyze the economic impacts of a proposed critical habitat designation. The DEA for the sickle darter found that the economic cost of implementing the rule will likely be limited to additional administrative effort in considering adverse modification of sickle darter habitat during Section 7 consultations.  

How do I submit comments on this proposal?  

For directions on how to submit comments, visit the Federal eRulemaking Portal at In the Search box, enter FWS-R4-ES-2020-0094, which is the docket number for this rulemaking. Comments must be received by 03/27/2023. We must receive requests for a public hearing, in writing, at the address shown below by 03/27/2023.

FOR FURTHER INFORMATION CONTACT:  Daniel Elbert, Field Supervisor, U.S. Fish and Wildlife Service, Tennessee Ecological Services Field Office, 446 Neal Street, Cookeville, TN 38501-4027; telephone 931-254-9617.   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. 

Story Tags

Endangered and/or Threatened species