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Frequently Asked Questions 



Q: When were the freshwater mussels listed under the Endangered Species Act (ESA)?

A: The U.S. Fish & Wildlife Service (Service) listed 11 freshwater mussels from the Mobile River Basin on March 17, 1993.

Q : Which freshwater mussels were listed?

A : The listed Mobile River Basin mussels are: fine-lined pocketbook (Lampsilis altilis), orange-nacre mucket (Lampsilis perovalis), Alabama moccasinshell (Medionidus acutissimus), Coosa moccasinshell (Medionidus parvulus), ovate clubshell (Pleurobema perovatum), southern clubshell (Pleurobema decisum), dark pigtoe (Pleurobema furvum), southern pigtoe (Pleurobema georgianum), triangular kidneyshell (Ptychobranchus greenii), upland combshell (Epioblasma metastriata), and southern acornshell (Epioblasma othcaloogensis). The fine-lined pocketbook, orange-nacre mucket and Alabama moccasinshell are listed as threatened and the remaining eight species – Coosa moccasinshell, ovate clubshell, southern clubshell, dark pigtoe, southern pigtoe, triangular kidneyshell, upland combshell and southern acornshell – are listed as endangered.

Q: Why were the mussels listed?

A: The mussels decline was brought about by river and stream modifications, such as dams, dredging and channelization, which destroyed free-flowing water habitats. As a result, these mussels were eliminated from extensive portions of their ranges in the Mobile Basin. Surviving populations were small and isolated from each other by impounded waters. Many of these isolated populations eventually were eliminated by local sources of pollution from mine and municipal discharges or runoff from other land use activities. Surviving populations of the mussels continue to be small and isolated, and are vulnerable to local pollution sources and some land use activities.

Q: What is a mussel?

A: Mussels – also known as shellfish, clams, bivalves, and unionids, are bivalve mollusks, that have two shells hinged together surrounding a soft, fleshy body. Freshwater mussels are related to oysters, clams, snails and squids. Mussels live in the sand and gravel bottoms of streams and rivers. Some species live as long as 70 years with the right conditions and depending on the species, they can measure from 2-12 inches across.


Q: What is critical habitat?

A: Critical habitat is a term defined and used in the Endangered Species Act (ESA) of 1973, as amended. It refers to specific geographic areas that are essential for the conservation of a threatened or endangered species and that may require special management consideration or protection. These areas do not necessarily have to be occupied by the species at the time of designation. This means that areas must be identified which will allow for the protection of the current population, and any population increases that may be required to achieve recovery (allowing the species to be removed from the endangered and threatened species list).

Q: Why is the Service proposing critical habitat for 11 mussels?

A: When the Service makes a not determinable finding, we are required under the Act to make a final determination regarding designation of critical habitat for species. We are also complying with a court order to make a proposed critical habitat designation. This proposal reflects our interpretation of the recent judicial opinions on critical habitat designation and the standards placed on the Services for making a prudency determination.

Q: What geographic areas are being proposed as critical habitat for the mussels?

A: We are proposing 26 critical river and stream segments (habitat units) in Alabama, Georgia, Mississippi and Tennessee. Critical habitat units include portions of the:


Q: How large of an area does the mussels’ critical habitat proposal encompass?

A: The 26 critical habitat units encompass approximately 1,093 miles of stream and river channel, within the ordinary high water line.

Q: Why is the critical habitat designation such a broad geographic range across four States? Doesn’t the ESA state that the entire range will not be designated?

A: After thorough analysis, the Service identified these areas as providing the best opportunities to conserve these species. This proposed designation includes only a small portion of these species’ historic ranges. A large proportion of the Basins’ streams and rivers that historically supported these mussels have been altered by channelization, dams and their impounded waters, or other modifications. Other areas were not considered for the proposed designation because of limited habitat availability, isolation, degraded habitat, and/or low management value or potential. It is our determination that the 26 critical habitat units in this proposed designation include habitats that are essential for the conservation of the 11 mussel species.

Q: Are the mussels located outside of the designated critical habitat areas still protected?

A: Yes. Because the 11 mussels are listed species, they are protected regardless of whether they are inside or outside of an area designated as critical habitat. When critical habitat is designated, Federal agencies are also required to ensure that their activities will not destroy or adversely modify critical habitat. Also, as a listed species, the mussels are protected from “take” throughout its range regardless of whether critical habitat has been designated. “Take” is defined to include harass, harm, pursue, hunt, shoot, wound, kill, trap, or collect; or to attempt any of these. Harm is further defined in our regulations (50 CFR 7.3) to include significant habitat modification or degradation that results in death or injury to listed species by significantly impairing essential behavioral patterns, including breeding, feeding, or sheltering.


Q: How did the Service determine which areas to designate as critical habitat?

A: Biologists identified the physical and/or biological habitat features needed for life and successful reproduction of the species. These features are known as primary constituent elements and include, but are not limited to:

By law, we are required to identify sufficient areas containing these characteristics to ensure the conservation of the species.

Q: What are the primary constituent elements for the mussels?

A: Based on the best available information, primary constituent elements essential for the conservation of the 11 mussels species include:

  1. Stable stream and river channels and banks;
  2. A flow regime (i.e., the magnitude, frequency, duration, and seasonality of discharge over time) necessary for normal behavior, growth, and survival of all life stages of mussels and their fish hosts in the river environment;
  3. Water quality, including temperature, pH, hardness, turbidity, oxygen content, and other chemical characteristics, necessary for normal behavior, growth, and viability of all life stages;
  4. Sand, gravel, and/or cobble substrates with low to moderate amounts of fine sediment, low amounts of attached filamentous algae, and other physical and chemical characteristics necessary for normal behavior, growth, and viability of all life stages;
  5. Fish hosts, with adequate living, foraging, and spawning areas for them; and,
  6. Few or no competitive nonnative species.

Q: Does a critical habitat designation affect all activities that occur within the designated area?

A: No. An area designated as critical habitat is not a refuge or a sanctuary for the species. Most use of critical habitat by the public will not be affected by this critical habitat designation. Activities such as recreational boating, canoeing, swimming and commercial boat traffic, that do not involve a Federal action that may affect critical habitat, will be unaffected by the designation. Private land use activities, such as farming and silviculture, would also be unaffected. Federal activities, or actions permitted, licenced, or funded by Federal agencies, will require consultation with the Service if they are likely to adversely modify critical habitat. In such cases, the Service will work with the Federal agency to identify alternatives where the project may proceed without adverse modification to critical habitat.

Q: What does it mean “to consult?”

A: Consultation is a process by which Federal agencies use the Services’ expertise to evaluate the potential effects of a proposed action on ESA listed species and their critical habitats. Consultation may also identify alternatives to the proposed action to avoid adverse effects on listed species and their habitats.

Q: What is the extent of the additional consultation burden to the Federal agency? To a permit applicant?

A: Federal agencies are already required to consult with the Services under the ESA whenever a proposed action might impact a listed species or its habitat. Thus, the designation of critical habitat will not increase the consultation burden to either the Federal agency or the permit applicant.

Q: Will the critical habitat designation delay Federal decisions on permits or funding?

A: Under the ESA, we have specific time frames in which to complete the consultation process with action agencies. These time frames remain the same whether or not there is critical habitat within the project area. Designation of critical habitat for the mussels notifies the Federal action agencies and the public that permits and other authorizations for activities within these designated critical habitat areas must comply with section 7 consultation requirements. For each section 7 consultation, we already review the direct and indirect effects of the proposed projects on mussels, and will continue to do so for critical habitat if it is designated.

Q: What activities could adversely affect critical habitat and may require special management considerations for the mussels?


A: Activities that may affect critical habitat include, but are not limited to, the following:

Q: What does it mean to “destroy” or “adversely modify” critical habitat?

A: “Destruction or adverse modification of designated critical habitat” is defined as a direct or indirect alteration that appreciably diminishes the value of the critical habitat for both the survival and recovery of the species (50 CFR 402.02). Such alterations include, but are not limited to, adverse changes to the physical or biological features, i.e., the primary constituent elements, that were the basis for determining the habitat to be critical.

Q: Are all areas within the proposed critical habitat boundaries for the mussels considered critical habitat?

A: In order for an area to be designated as critical habitat, the area has to contain primary constituent elements which are the physical and biological elements essential to support the life cycle needs of the species. Critical habitat does not include existing developed sites such as dams, piers, marinas, bridges, boat ramps, exposed oil and gas pipelines, and similar structures.

Q: What specific methods were used to propose critical habitat for the mussels?

A: This proposal is based on the best scientific information available concerning the species’ present and historic range, habitat, biology, and threats. We reviewed and summarized the current information available on the mussels. The information used included known locations; the final listing rule for the mussels; recent biological surveys and reports; peer-reviewed literature; our recovery plan; and discussions and recommendations from mussels experts.

Q: What is the impact of designating critical habitat on private lands and private landowners?

A: The designation of critical habitat on private land will have no impact on private landowner activities that do not require Federal funding or permits. The designation of critical habitat is only applicable to Federal activities.

Q: Do listed species in critical habitat areas receive more protection?

A: Species that are listed as endangered or threatened are protected regardless of whether they are inside or outside of an area designated as critical habitat. When critical habitat is designated, Federal agencies are also required to ensure that their activities will not destroy or adversely modify critical habitat.

Q: If a listed species is already protected by the ESA and Federal agencies already consult with the Service, what benefit does critical habitat provide to the species?

A: Critical habitat provides non-regulatory benefits to the species by informing the public of areas that are important for the species recovery and where conservation actions would be most effective. Designation of critical habitat can help focus conservation activities for a listed species by identifying areas that contain the physical and biological features that are essential for conservation of that species, and can alert the public as well as land-managing agencies to the importance of those areas.

Q: Must Federal agencies consult with the Service even where critical habitat has not been designated?

A: Even when there is no critical habitat designation, Federal agencies must consult with the Service on actions that may affect listed species, in order to ensure that any action they carry out, fund or authorize is not likely to jeopardize a listed species continued existence. Where critical habitat is designated, a consultation also ensures that the critical habitat is not destroyed or adversely modified.

Q: Does the ESA consider economic consequences as a part of designating critical habitat?

A: Yes. Unlike ESA listing decisions, the Service must take into account the economic impact, as well as any other relevant impacts, of specifying any particular area as critical habitat. We may exclude any area from critical habitat if we determine that the benefits of excluding it outweigh the benefits of specifying the area as a part of critical habitat, unless we determine that the failure to designate the area as critical habitat will result in the extinction of the species. The Service is preparing a draft analysis of the economic impacts of designating these areas as critical habitat, and will publish it in the Federal Register for public review and comment.

Q: What are the recovery goals for the mussels?

A: The Mobile River Basin Aquatic Ecosystem Recovery Plan (U.S. Fish and Wildlife Service 2000), considers that downlisting or delisting these mussels is unlikely in the foreseeable future because of the extent of their decline, the fragmentation and isolation of their habitats, and continuing impacts upon their habitats. Compounding these problems is a lack of information on specific habitat and life history requirements of these species, or on the physical threats that confront them (e.g., sediment, nutrient, and other pollutant sensitivities, etc.). Threats compounded by habitat fragmentation and isolation can be reduced by increasing the number, expanding the range, and increasing the density of populations. Therefore, the recovery plan emphasizes the approach of protection of existing populations and their currently occupied habitats, enhancement and restoration of habitats, and population management, including augmentation and reintroduction of the species into portions of their historic ranges, as measures to secure the species from status deterioration and extinction.

Q: How many species have critical habitat designations?

A: The Service has designated critical habitat for 162 of the 1,260 species federally listed as threatened or endangered. In the Mobile River Basin, critical habitat has been designated in the Conasauga River, Polk and Bradley counties, Tennessee, and Murray and Whitfield Counties, Georgia, for the amber darter and the Conasauga logperch.

Q: What type of comments is the Service seeking?

A: We intend that any final action resulting from this proposal be as accurate and as effective as possible. Therefore, we solicit comments or suggestions from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this proposed rule. We are particularly interested in comments concerning:

    (1) The reasons why any area should or should not be determined to be critical habitat as provided by section 4 of the Act and 50 CFR 424.12(a)(1), including whether the benefits of designation will outweigh any threats to the species due to designation;

    (2) Specific information on the number and distribution of the 11 mussel species and what habitat is essential to the conservation of these species and why;

    (3) Whether areas within proposed critical habitat are currently being managed to address conservation needs of the mussels;

    (4) Current or planned activities in the subject areas and their possible impacts on proposed critical habitat;

    (5) Any foreseeable economic or other impacts resulting from the proposed designation of critical habitat, in particular, any impacts on small entities or families;

    (6) Economic and other values associated with designating critical habitat for the mussels, such as those derived from non-consumptive uses (e.g., hiking, camping, wildlife-watching, enhanced watershed protection, improved air quality, increased soil retention, “existence values” and reductions in administrative costs).

Q: How can you submit comments on the proposed critical habitat designation for mussels?

A: The Service will consider comments and information received by June 24, 2003. Written comments and information on the proposal should be mailed, faxed, or delivered in person to U.S. Fish and Wildlife Service, Attn: Paul Hartfield, 6578 Dogwood View Parkway, Suite A, Jackson, MS 39213; Fax: 601-965-4043, or sent by electronic mail to All comments received during the comment period, both written and presented at public hearings, will receive equal consideration.

Q: Who should you contact for more information?

A: Paul Hartfield at 601-321-1125 or Connie Light Dickard at 601-321-1121, both at the same address as above: U.S. Fish and Wildlife Service, Mississippi Field Office, 6578 Dogwood View Parkway, Suite A, Jackson, MS 39213.