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Daily Rules, Proposed Rules, and Notices of the Federal Government

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2012-0004; 4500030113]

RIN 1018-AY06

Endangered and Threatened Wildlife and Plants; Endangered Species Status for the Fluted Kidneyshell and Slabside Pearlymussel and Designation of Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to list the fluted kidneyshell (Ptychobranchus subtentum) and slabside pearlymussel (Pleuronaia dolabelloides) as endangered species under the Endangered Species Act of 1973, as amended (Act), and we propose to designate critical habitat for both species. These two species are endemic to portions of the Cumberland and Tennessee River systems of Alabama, Kentucky, Mississippi, Tennessee, and Virginia. In total, approximately 2,218 river kilometers (1,380 river miles) are being proposed for designation as critical habitat. The proposed critical habitat for fluted kidneyshell is located in Limestone County, Alabama; Jackson, Laurel, McCreary, Pulaski, Rockcastle, and Wayne Counties, Kentucky; Bedford, Claiborne, Cocke, Fentress, Franklin, Giles, Grainger, Greene, Hamblen, Hancock, Hickman, Humphreys, Jefferson, Knox, Lincoln, Marshall, Maury, Moore, Morgan, Overton, Perry, Pickett, Polk, Scott, and Sevier Counties, Tennessee; and Bland, Lee, Russell, Scott, Smyth, Tazewell, Washington, and Wythe Counties, Virginia. The proposed critical habitat for slabside pearlymussel is located in Colbert, Jackson, Limestone, Madison, and Marshall Counties, Alabama; Tishomingo County, Mississippi; Bedford, Bledsoe, Claiborne, Cocke, Franklin, Giles, Greene, Hamblen, Hancock, Hickman, Humphreys, Lincoln, Marion, Marshall, Maury, Moore, Perry, Polk, and Sequatchie Counties, Tennessee; and Bland, Lee, Russell, Scott, Smyth, Tazewell, Washington, and Wythe Counties, Virginia.
DATES: We will accept comments received or postmarked on or before December 3, 2012. We must receive requests for public hearings, in writing, at the address shown in theFOR FURTHER INFORMATION CONTACTsection by November 19, 2012.
ADDRESSES: (1)Electronically:Go to the Federal eRulemaking Portal:http://www.regulations.gov.In the Search field, enter Docket No. FWS-R4-ES-2012-0004, which is the docket number for this rulemaking. Then, click the Search button. You may submit a comment by clicking on "Comment Now!"

(2)By hard copy:Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R4-ES-2012-0004; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS 2042-PDM; Arlington, VA 22203.

We request that you send comments only by the methods described above. We will post all comments onhttp://www.regulations.gov.This generally means that we will post any personal information you provide us (see the Information Requested section below for more information).

The coordinates or plot points or both from which the maps are generated are included in the administrative record for this critical habitat designation and are available athttp://www.fws.gov/cookeville, http://www.regulations.govat Docket No. [FWS-R4-ES-2012-0004], and at the Tennessee Ecological Services Field Office) (seeFOR FURTHER INFORMATION CONTACT). Any additional tools or supporting information that we may develop for this critical habitat designation will also be available at the above locations.

FOR FURTHER INFORMATION CONTACT: Mary Jennings, Field Supervisor, U.S. Fish and Wildlife Service, Tennessee Ecological Services Field Office, 446 Neal Street, Cookeville, TN 38501; telephone 931-528-6481; facsimile 931-528-7075. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:

This document consists of: (1) A proposed rule to list the fluted kidneyshell (Ptychobranchus subtentum) and slabside pearlymussel (Pleuronaia dolabelloides) as endangered species; and (2) proposed critical habitat designations for these two species.

Executive Summary

Why we need to publish a rule.Under the Act, a species or subspecies may warrant protection through listing if it is an endangered or threatened species throughout all or a significant portion of its range. Both species have been eliminated from more than 50 percent of the streams from which they were historically known, and are now limited to a handful of viable populations, all of which are facing a variety of threats, including impoundments, mining, poor water quality, excessive sedimentation, and environmental contaminants.

The basis for our action.Under the Act, a species may be determined to be endangered or threatened based on any of five factors: (A) Destruction, modification, or curtailment of its habitat or range; (B) overutilization; (C) disease or predation; (D) inadequate existing regulatory mechanisms; or (E) other natural or manmade factors. These two mussel species are facing threats due to three of these five factors (A, D, and E). The Act also requires that the Service designate critical habitat at the time of listing provided that it is prudent and determinable. We have determined that designating critical habitat is both prudent and determinable (see Critical Habitat for the Fluted Kidneyshell and Slabside Pearlymussel section below), and propose a total of approximately 2,218 river kilometers (rkm) (1,380 river miles (rmi)) of critical habitat in five States. Twenty-four units covering approximately 1,899 river kilometers (rkm) (1,181 river miles (rmi)) of critical habitat are being proposed for the fluted kidneyshell in Alabama, Kentucky, Tennessee, and Virginia. Thirteen units covering approximately 1,562 rkm (970 rmi) of critical habitat are being proposed for the slabside pearlymussel in Alabama, Mississippi, Tennessee, and Virginia.

We will seek peer review.In addition to seeking public comments, we will solicit peer review of this proposal from at least three experts knowledgeable in mussel biology and basic conservation biology principles and concepts. Because we will consider all comments and information received during the comment period, our final determinations may differ from this proposal

Information Requested

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments orinformation from other concerned governmental agencies, the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:

(1) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to these species and regulations that may be addressing those threats.

(2) Additional information concerning the historical and current status, range, distribution, and population size of either of these species, including the locations of any additional populations.

(3) Any information on the biological or ecological requirements of these species, and ongoing conservation measures for the species and their habitat.

(4) Any information regarding water quality data that may be helpful in determining the water quality parameters necessary for the fluted kidneyshell and the slabside pearlymussel.

(5) Current or planned activities in the areas occupied by these species and possible impacts of these activities on these species.

(6) The factors that are the basis for making a listing determination for a species under section 4(a) of the Act (16 U.S.C. 1531et seq.), which are:

(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.

(7) The reasons why we should or should not designate habitat as “critical habitat” under section 4 of the Act including whether there are threats to these species from human activity, the degree of which can be expected to increase due to the designation, and whether that increase in threat outweighs the benefit of designation such that the designation of critical habitat may not be prudent.

(8) Specific information on:

(a) The amount and distribution of habitat for the fluted kidneyshell and slabside pearlymussel;

(b) What areas, that were occupied at the time of the proposed listing and that contain features essential to the conservation of these species, should be included in the designation and why;

(c) Special management considerations or protection that may be needed in critical habitat areas we are proposing, including managing for the potential effects of climate change; and

(d) What areas not occupied at the time of the proposed listing are essential for the conservation of these species and why.

(9) Land use designations and current or planned activities in the subject areas and their possible impacts on proposed critical habitat.

(10) Information on the projected and reasonably likely impacts of climate change on these species and proposed critical habitat.

(11) Any probable economic, national security, or other relevant impacts of designating any area that may be included in the final designation; in particular, we seek information on any impacts on small entities or families, and the benefits of including or excluding areas that exhibit these impacts.

(12) Whether any specific areas we are proposing for critical habitat designation should be considered for exclusion under section 4(b)(2) of the Act, and whether the benefits of potentially excluding any specific area outweigh the benefits of including that area under section 4(b)(2) of the Act.

(13) Any impact that critical habitat designation would have, positive or negative, on conservation efforts associated with designated nonessential experimental populations for other listed species in the lower Holston and French Broad river systems in Tennessee, or the North Fork Holston River in Virginia.

(14) Information on habitat suitability for these two mussels in the proposed units that are not occupied at the time of the proposed listing, including the Rockcastle River, Kentucky, and the Sequatchie River, Tennessee.

(15) Whether we could improve or modify our approach to designating critical habitat in any way to provide for greater public participation and understanding, or to better accommodate public concerns and comments.

Please note that submissions merely stating support for or opposition to the action under consideration without providing supporting information, although noted, will not be considered in making a determination, as section 4(b)(1)(A) of the Act directs that determinations as to whether any species is a threatened or endangered 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 inADDRESSES. We request that you send comments only by the methods described inADDRESSES.

If you submit information viahttp://www.regulations.gov,your entire submission—including any personal identifying information—will be posted on the Web site. 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. We will post all hardcopy submissions onhttp://www.regulations.gov.Please include sufficient information with your comments to allow us to verify any scientific or commercial information you include.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection onhttp://www.regulations.gov,or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Tennessee Ecological Services Field Office (seeFOR FURTHER INFORMATION CONTACT).

Previous Federal Actions

The fluted kidneyshell was first identified as a candidate for protection under the Act in the October 25, 1999,Federal Register(64 FR 57534). Candidate species are those taxa for which the Service has sufficient information on their biological status and threats to list as an endangered or threatened species under the Act but for which the development of a listing regulation has been precluded to date by other higher priority listing activities. Candidates are assigned listing priority numbers (LPNs) based on immediacy and the magnitude of threat, as well as their taxonomic status. A lower LPN corresponds to a higher conservation priority, and we consider the LPN when prioritizing and funding conservation actions. In our 1999 (64 FR 57534), 2001 (66 FR 54808), 2002 (67 FR 40657), 2004 (69 FR 24876), 2005 (70 FR 24870), and 2006 (71 FR 53756)Federal RegisterCandidate Notices of Review, we identified the species as having an LPN of five, in accordance with our priority guidance published on September 21, 1983 (48 FR 43098). An LPN of five reflects threats that are nonimminent and high in magnitude, as well as the taxonomic classification of the fluted kidneyshell as a full species. We also determined that publication of a proposed rule to list the fluted kidneyshell was precluded by our work on higher priority listing actions. On May 11, 2004, we received a petition to list the fluted kidneyshell as anendangered species. We published our petition finding in the 2005 Candidate Notice of Review (70 FR 24869), and have done so annually in subsequent years.

On December 6, 2007 (72 FR 69034), we changed the LPN for the fluted kidneyshell from five to two. A listing priority of two reflects threats that are both imminent and high in magnitude, as well as the taxonomic classification of the fluted kidneyshell as a full species. In our 2008 (73 FR 75176), 2009 (74 FR 57804), 2010 (75 FR 69222), and 2011 (76 FR 66370) Candidate Notices of Review, we retained a listing priority number of two for this species.

The slabside pearlymussel was first identified as a candidate for protection under the Act in the May 22, 1984,Federal Register(49 FR 21664). As a candidate, it was assigned a “Category 2” designation, which was given to those species with some evidence of vulnerability, but for which additional biological information was needed to support a proposed rule to list as endangered or threatened. In our 1989 (54 FR 554), 1991 (56 FR 58804), and 1994 (59 FR 58982)Federal RegisterCandidate Notices of Review, we retained a Category 2 designation for this species. Assigning categories to candidate species was discontinued in our Candidate Notice of Review dated February 28, 1996, and only species for which the Service had sufficient information on biological vulnerability and threats to support issuance of a proposed rule were retained as candidate species (61 FR 7596).

On October 25, 1999, we identified the slabside pearlymussel in theFederal Registeras a candidate species with a listing priority number of five (64 FR 57534). In our 2001 (66 FR 54808), 2002 (67 FR 40657), 2004 (69 FR 24876), 2005 (70 FR 24870), 2006 (71 FR 53756), and 2007 (72 FR 69034) Candidate Notices of Review, we determined that publication of a proposed rule to list the species was precluded by our work on higher priority listing actions and retained a listing priority number of five for this species, in accordance with our priority guidance published on September 21, 1983 (48 FR 43098). We published a petition finding for slabside pearlymussel in the 2005 Candidate Notice of Review (70 FR 24870) in response to a petition received on May 11, 2004, and have published annual petition findings in subsequent Candidate Notices of Review.

On December 10, 2008 (73 FR 75176), we changed the listing priority number for the slabside pearlymussel from five to two. In our 2009 (74 FR 57804), 2010 (75 FR 69222), and 2011 (76 FR 66370) Candidate Notices of Review, we retained a listing priority number of two for this species.

Background

It is our intent to discuss only those topics directly relevant to the listing and critical habitat designations for the fluted kidneyshell and slabside pearlymussel in this proposed rule. A summary of topics relevant to this proposed rule is provided below. Additional information on both species may be found in the most recent Candidate Notice of Review, which was published October 26, 2011 (76 FR 66370).

Introduction

North American mussel fauna are more biologically diverse than anywhere else in the world, and historically numbered around 300 species (Williamset al.1993, p. 6). Mussels are in decline, however, and in the past century have become more imperiled than any other group of organisms (Williamset al.2008, p. 55). Approximately 72 percent of North America's mussel species are considered vulnerable to extinction or possibly extinct (Williamset al.1993, p. 6). Within North America, the southeastern United States is the hot spot for mussel diversity. Seventy-five percent of southeastern mussel species are in varying degrees of rarity or possibly extinct (Neveset al.1997, pp. 47-51). The central reason for the decline of mussels is the modification and destruction of their habitat, especially from dams, degraded water quality, and sedimentation (Neveset al.1997, p. 60; Bogan 1998, p. 376). These two mussels, like many other southeastern mussel species, have undergone considerable reductions in total range and population density.

Most studies of the distribution and population status of the fluted kidneyshell and slabside pearlymussel presented below were conducted after the early 1960s. Gordon and Layzer (1989, entire), Winston and Neves (1997, entire), and Parmalee and Bogan (1998, pp. 204-205) give most of the references for regional stream surveys. In addition to these publications, we have obtained more current, unpublished distribution and status information from State heritage programs, agency biologists, and other knowledgeable individuals.

These two species are bivalve mussels and are endemic to the Cumberland and Tennessee River drainages. The Cumberland River drainage originates in southeastern Kentucky and flows southwest across Tennessee before turning north and reentering Kentucky to empty into the lower Ohio River. The Cumberland River drainage spans the Appalachian Plateaus and Interior Low Plateaus Physiographic Provinces. The Tennessee River originates in southwest Virginia and western North Carolina, eastern Tennessee, and northern Georgia and flows southwesterly into western Tennessee and Alabama, then turns north and flows into Kentucky, before emptying into the Ohio River. The larger Tennessee River drainage spans five physiographic provinces, including the Blue Ridge, Valley and Ridge, Appalachian Plateaus, Interior Low Plateaus, and Coastal Plain.

Fluted Kidneyshell Taxonomy and Species Description

The fluted kidneyshell,Ptychobranchus subtentum(Say, 1825), is in the family Unionidae (Turgeonet al.1998, p. 36). The following description, biology, and life history of the fluted kidneyshell is taken from Parmalee and Bogan (1998, pp. 204-205) and Williamset al.(2008, pp. 627-629). The fluted kidneyshell is a relatively large mussel that reaches about 13 centimeters (cm) (5 inches (in)) in length. The shape of the shell is roughly oval elongate, and the solid, relatively heavy valves (shells) are moderately inflated. A series of flutings (parallel ridges or grooves) characterizes the posterior slope of each valve. Shell texture is smooth and somewhat shiny in young specimens, becoming duller with age. Shell color is greenish yellow, becoming brownish with age, with several broken, wide green rays. Internally, there are two types of teeth, which are raised, interlocking structures used to stabilize opposing shell halves. The pseudocardinal teeth are stumpy and triangular in shape. The lateral teeth are relatively heavy and nearly straight, with two in the left valve and one in the right valve. The color of the nacre (mother-of-pearl) is bluish-white to dull white with a wash of salmon in the older part of the shell (beak cavity).

Habitat and Life History

Mussels generally live embedded in the bottom of rivers and other bodies of water. They siphon water into their shells and across four gills that are specialized for respiration, food collection, and brooding larvae in females. Food items include detritus (disintegrated organic debris), algae, diatoms, and bacteria (Strayeret al.2004, pp. 430-431). Adult mussels can obtain their food by deposit feeding, pulling in food from the sediment and its interstitial (pore) water, and pedal-feeding directly from the sediment (Yeageret al.1994, pp. 217-221; Vaughn and Hakenkamp 2001, 1432-1438). Adults are filter feeders and generally orient themselves on or near the substrate surface to take in food and oxygen from the water column. Juveniles typically burrow completely beneath the substrate surface and are deposit or pedal (foot) feeders, meaning that they bring food particles that adhere to the foot while it is extended outside the shell inside the shell for ingestion, until the structures for filter feeding are more fully developed (Yeageret al.1994, pp. 200-221; Gatenbyet al.1996, p. 604). However, adults are also capable of deposit feeding and may do so depending on the availability of food resources (Nicholset al.2005, pp. 90-93).

Mussels tend to grow relatively rapidly for the first few years; then growth slows appreciably after sexual maturity, when energy is being diverted from growth to reproductive activities. Mussel longevity varies tremendously among species (from 4 to 5 years to well over 100 years), but most species live 10 to 50 years (Haag and Rypel 2011, pp. 230-236). Relatively large, heavy-shelled riverine species tend to be slower growing and have longer life spans. By thin-sectioning the valves, various authors have aged fluted kidneyshell from the Clinch River at 26 and 55 years (Henleyet al.2002, p. 19; Davis and Layzer 2012, p. 92). Females can become sexually mature at age 5 (Davis and Layzer 2012, p. 79).

The gametogenic cycle (annual cycle in the development of reproductive cells or gametes) of fluted kidneyshell, like most mussels, is probably regulated by annual temperature regimes (Davis and Layzer, p. 90). Most mussels, including the fluted kidneyshell, have separate sexes. Males expel sperm into the water column, which are drawn in by females through their incurrent apertures or siphons. It has been hypothesized that pheromones might trigger synchronous sperm release among males, because all fertilization observed by females from the Clinch River occurred in fewer than 5 days (Davis and Layzer 2012, p. 90). Fertilization takes place internally, and the resulting zygotes develop into specialized larvae, termed glochidia, inside the water tubes of the females' gills. The fluted kidneyshell, along with other members of its genus, is unique in that the marsupial portion of the outer gills (portion of a brooding female's gill which holds embryos and glochidia) are folded in a curtain-like fashion. The fluted kidneyshell is thought to have a late summer or early fall fertilization period with the glochidia overwintering. Davis and Layzer (2012, p. 90) observed embryo development within the marsupium (brood pouch) at 4 weeks after fertilization. The following spring or early summer, glochidia are released as conglutinates, which are similar to cold capsules or gelatinous containers with scores of glochidia within. Davis and Layzer (2012, p. 86) report an average of 208 conglutinates and an average fecundity (total reproductive output) of 247,000 glochidia per female. Davis and Layzer (2012, p. 92) report a skewed adult sex ratio of 1.9 females per 1 male in the Clinch River, in Tennessee, although the cause of the skewed ratio is unknown. Using the observed sex ratio and percent of females that were gravid, Davis and Layzer (2012, p. 92) hypothesized that some females go through reproductive “pausing” periods to acquire the energy reserves needed to produce gametes in subsequent years.

Glochidia must come into contact with a specific host fish(es) quickly in order for their survival to be ensured. Without the proper species of host fish, the glochidia will perish. Conglutinate masses often mimic food items of glochidial fish hosts in order to attract and infest potential host fishes. Fluted kidneyshell conglutinates are shaped like black fly (Simuliidae) pupae and have an adhesive end that sticks to silt-free stones on the stream bottom, with an orientation that is also similar to that of blackfly pupae (Barnhart and Roberts 1997, p. 17; Barnhartet al.2008, p. 377; Williamset al.2008, p. 628). Insects are common food items of many stream fishes, including the fluted kidneyshell's host fishes, which include the barcheek darter (Etheostoma obeyense), fantail darter (E. flabellare), rainbow darter (E. caeruleum), redline darter (E. rufilineatum), bluebreast darter (E. camurum), dusky darter (Percina sciera), and banded sculpin (Cottus carolinae). These fishes are tricked into thinking that they have an easy insect meal when in fact they have infected themselves with parasitic mussel glochidia (Parmalee and Bogan 1998, p. 205; Davis and Layzer 2012, p. 88).

After a few weeks parasitizing the host fish's gill, newly metamorphosed juveniles drop off to begin a free-living existence on the stream bottom. Unless they drop off in suitable habitat, they will perish. Thus, the complex life history of the fluted kidneyshell and other mussels has many critical steps that may prevent successful reproduction or recruitment of juveniles into existing populations or both.

The fluted kidneyshell occurs in medium-sized creeks to large rivers, inhabiting sand and gravel substrates in relatively shallow riffles and shoals with moderate to swift current (Williamset al.2008, p. 628). In comparison to some co-occurring species, the fluted kidneyshell demonstrates strong habitat specificity by being associated with faster flows, greater shear stress (force of water pressure and velocity on the substrate), and low substrate embeddedness (Ostby 2005, pp. 51, 142-3).

Historical Range and Distribution

The fluted kidneyshell is a Cumberlandian Region mussel, meaning it is restricted to the Cumberland (in Kentucky and Tennessee) and Tennessee (in Alabama, Kentucky, Tennessee, and Virginia) River systems. Historically, this species occurred in the Cumberland River mainstem from below Cumberland Falls in southeastern Kentucky downstream through the Tennessee portion of the river to the vicinity of the Kentucky-Tennessee State line. In the Tennessee River mainstem it occurred from eastern to western Tennessee. Records are known from the following Cumberland River tributaries: Horse Lick Creek [KY], Middle Fork Rockcastle River [KY], Rockcastle River [KY], Buck Creek [KY], Rock Creek [KY], Kennedy Creek [KY], Little South Fork [KY], Big South Fork [KY, TN], Pitman Creek [KY], Otter Creek [KY], Wolf River [TN], Town Branch [TN], West Fork Obey River [TN], Obey River [TN], Caney Fork [TN], South Harpeth River [TN], and West Fork Red River [KY]. In addition, it is known from the following Tennessee River tributaries: South Fork Powell River [VA], Powell River [TN, VA], Indian Creek [VA], Little River [VA], Clinch River [TN, VA], Copper Creek [VA], North Fork Holston River [TN, VA], Big Moccasin Creek [VA], Middle Fork Holston River [VA], South Fork Holston River [TN, VA], Holston River [TN], Nolichucky River [TN], West Prong Little Pigeon River [TN], Tellico River [TN], French Broad River [TN], Little Tennessee River [TN], Hiwassee River [TN], Flint River [AL], Limestone Creek [AL], Elk River [AL, TN], Shoal Creek [AL], Buffalo River [TN], and Duck River [TN] (Gordon and Layzer 1989, entire; Winston and Neves 1997, entire; Parmalee and Bogan 1998, pp. 204-205; Layzer and Scott 2006, p. 481). The fluted kidneyshell's known historical and current occurrences, by water body and county, are shown in Table 1 below.

Table 1—Known Historical and Current Occurrences for the Fluted Kidneyshell Water body Drainage County State Historical or current Cumberland River Cumberland McCreary, Pulaski, Russell KY Historical. Cumberland River Cumberland Stewart TN Historical. Middle Fork Rockcastle River Cumberland Jackson KY Historical and Current. Horse Lick Creek Cumberland Jackson, Rockcastle KY Historical and Current. Rockcastle River Cumberland Laurel, Pulaski, Rockcastle KY Historical. Buck Creek Cumberland Pulaski KY Historical and Current. Big South Fork Cumberland River Cumberland McCreary, Pulaski KY Historical and Current. Big South Fork Cumberland River Cumberland Fentress, Morgan, Scott TN Historical and Current. Rock Creek Cumberland McCreary KY Historical and Current. Little South Fork Cumberland River Cumberland McCreary, Wayne KY Historical and Current. Kennedy Creek Cumberland Wayne KY Historical. Pitman Creek Cumberland Pulaski KY Historical. Otter Creek Cumberland Wayne KY Historical. Wolf River Cumberland Fentress, Pickett TN Historical and Current. Town Branch Cumberland Pickett TN Historical and Current. Obey River Cumberland ? TN Historical. West Fork Obey River Cumberland Overton TN Historical and Current. Caney Fork River Cumberland ? TN Historical. South Harpeth River Cumberland Davidson TN Historical. West Fork Red River Cumberland Todd KY Historical. South Fork Powell River Tennessee Wise VA Historical. Powell River Tennessee Claiborne, Hancock TN Historical and Current. Powell River Tennessee Campbell, Union TN Historical. Powell River Tennessee Lee VA Historical and Current. Indian Creek Tennessee Tazewell VA Historical and Current. Clinch River Tennessee Hancock TN Historical and Current. Clinch River Tennessee Anderson, Claiborne, Grainger, Roane, Union TN Historical. Clinch River Tennessee Russell, Scott, Tazewell, Wise VA Historical and Current. Little River Tennessee Russell, Tazewell VA Historical and Current. Copper Creek Tennessee Scott VA Historical and Current. North Fork Holston River Tennessee Hawkins, Sullivan TN Historical. North Fork Holston River Tennessee Bland, Scott, Smyth, Washington VA Historical and Current. Big Moccasin Creek Tennessee Scott VA Historical and Current. Middle Fork Holston River Tennessee Smyth VA Historical and Current. South Fork Holston River Tennessee Sullivan TN Historical. South Fork Holston River Tennessee Washington VA Historical. Holston River Tennessee Grainger, Hamblen, Jefferson, Knox TN Historical. French Broad River Tennessee ? TN Historical. Tennessee River Tennessee Colbert, Jackson, Lauderdale AL Historical. Tennessee River Tennessee Decatur, Knox, Meigs, Rhea TN Historical. Nolichucky River Tennessee Greene TN Historical and Current. West Prong Little Pigeon River Tennessee Sevier TN Historical. Tellico River Tennessee Monroe TN Historical. Little Tennessee River Tennessee Monroe TN Historical. Hiwassee River Tennessee Polk TN Historical. Flint River Tennessee Madison AL Historical. Limestone Creek Tennessee Limestone AL Historical. Elk River Tennessee Limestone AL Historical. Elk River Tennessee Coffee, Franklin TN Historical. Shoal Creek Tennessee Limestone AL Historical. Duck River Tennessee Bedford, Marshall, Maury TN Historical and Current. Buffalo River Tennessee Lewis TN Historical. Note:A ? represents a lack of specific locational information in the museum and literature record.

Prior to 1980, the fluted kidneyshell was fairly widespread and common in many Cumberlandian Region streams based on collections in museums and from the literature record. The extirpation of this species from numerous streams within its historical range indicates that substantial population losses and range reductions have occurred.

Current Range and Distribution

In this document, populations of the fluted kidneyshell are generally considered extant (current) if live individuals or fresh dead specimens have been collected since circa 1980. This criterion (circa 1980) was chosen because a large number of collections were conducted in the 1980s in the Cumberland and Tennessee River systems and due to the longevity of these species (40-55 years), they are still thought to occur in these areas.

Some of the historical occurences have not been surveyed since the 1980s. Based on this criterion, the species appears to be limited to Horse Lick Creek [KY], Middle Fork Rockcastle River [KY], Buck Creek [KY], Rock Creek [KY], Little South Fork Cumberland River [KY], Big South Fork Cumberland River [KY, TN], Wolf River [TN], Town Branch [TN], and West Fork Obey River [TN] in the Cumberland River system; and the Powell River [TN, VA], Indian Creek [VA], Little River[VA], Clinch River [TN, VA], Copper Creek [VA], North Fork Holston River [VA], Big Moccasin Creek [VA], Middle Fork Holston River [VA], Nolichucky River [TN], and Duck River [TN] in the Tennessee River system (see Table 1). Where two or more stream populations occur contiguously with no barriers, such as impoundments or long reaches of unoccupied habitat, they are considered single population segments or clusters. Multi-stream population segments include the Wolf River and its tributary Town Branch in the Cumberland River system, and Clinch River and Copper Creek (but not the other two upper Clinch tributaries, Indian Creek and Little River) in the Tennessee River system. Thus, we consider 17 of 40 populations of fluted kidneyshell to be extant. The fluted kidneyshell has been eliminated from more than 50 percent of streams from which it was historically known.

Other populations considered extant at the time this species was elevated to candidate status in 1999 (e.g., Rockcastle River, Kennedy Creek) are now considered to be extirpated. In addition, the population in the upper North Fork Holston River, although still large, has declined substantially since circa 2000. The North Fork Holston River population is predominately composed of large individuals, unlike the Clinch River population, which is skewed towards smaller size classes (Ostbyet al.2010, pp. 7, 22-24). These differences in population characteristics are a clear indication that recruitment in the Clinch River population is more observable than the population in the North Fork Holston River.

Resource managers have been making attempts to reintroduce the fluted kidneyshell into historical habitat over the past decade. In Tennessee, thousands of individuals of the species have been reintroduced into three sites in the upper Duck River, and into two sites in the Nolichucky River, by Tennessee Wildlife Resource Agency (TWRA) biologists translocating adult individuals from the Clinch River (Hubbs 2011, unpubl. data). In 2010, six individuals were collected during a quantitative survey at Lillard's Mill in the Duck River, confirming some level of survival and persistence of the reintroduced population (Hubbs 2011, unpubl. data). The individuals collected appeared in good condition and had grown noticeably since their release (as evidenced by external shell marks), but recruitment has yet to be documented (Hubbs 2011, unpubl. data). In 2008, the Kentucky Department of Fish and Wildlife Resources (KDFWR) translocated 144 individuals from the Clinch River into the Big South Fork of the Cumberland River, Kentucky (Hubbs 2011, unpubl. data). It is not known if the Nolichucky or Big South Fork reintroductions have been successful. Approximately 691 adult individuals of the species have been translocated from the Clinch River, Tennessee, into the Little Tennessee River bypass reach below Calderwood Dam, Tennessee (Moles 2012, pers. comm.). The Virginia Department of Game and Inland Fisheries (VDGIF) reintroduced 58 adults into Indian Creek, a tributary to the Clinch River, using Clinch River stock. They have also propagated and released 562 juveniles into the North Fork Holston River (Duncan 2012, pers. comm.).

The extant fluted kidneyshell populations (including the potentially reintroduced populations) in the Cumberlandian Region generally represent small, isolated occurrences. Only in the Clinch River is a population of the fluted kidneyshell known to be large, stable, and viable, but in a relatively short reach of river primarily in the vicinity of the Tennessee-Virginia State line. Jones (2012, unpub. data) estimates 500,000 to 1,000,000 individuals occur in the Clinch River from just a 32-river-kilometer (rkm) (20-river-mile (rmi)) reach (rkm 309 to 277 (rmi 172 to 192)). Live adults and juveniles have been observed over the past 10 years in shoal habitats in the upper Clinch River, Virginia, particularly at and above Cleveland Islands, and many more fresh dead shells have been collected in muskrat middens in this reach. Eckert and Pinder (2010, pp. 23-30) collected 18 individuals in quantitative samples and 11 individuals in semi-quantitative samples in the Clinch River at Cleveland Island in 2008, and 15 individuals in quantitative samples and 62 individuals in semi-quantitative samples in the Clinch River at Cleveland Island in 2002. Ostby and Angermeier (2011, entire) found two live individuals in the Little River (tributary to Clinch River). Henleyet al.(1999, pp. 20, 22) collected live individuals at 6 of 25 sites surveyed in the Middle Fork Holston River in 1997 and 1998. The fluted kidneyshell was found in Copper Creek between creek rkm 2 and 31 (rmi 1 and 19) (Hanlonet al.2009, pp. 15-17). Pettyet al.(2006, pp. 4, 36) found the species between Copper Creek rkm 24 and 31 (rmi 15 and 19) and reported evidence of reproduction and recruitment of the species at these locations. In 2008-09, 35 live individuals were found at 5 of 21 sites sampled in the Powell River, in both Tennessee and Virginia, and there was some indication of relatively recent recruitment (Johnsonet al.in press, Table 4). Ostbyet al.(2010, pp. 16-20) observed 772 individuals during qualitative surveys and 10 individuals in quantitative surveys in the North Fork Holston River, Virginia.

Live fluted kidneyshell have not been collected in the Middle Fork Rockcastle River since the mid-1980s (Layzer and Anderson 1992, p. 64). Haag and Warren (2004, p. 16) collected only fresh dead shell material in Horse Lick Creek, and reported that a small, extremely vulnerable population of the fluted kidneyshell may exist there, but at very low levels that they were not able to detect. Warren and Haag (2005, pp. 1384, 1388-1396) reported a vast reduction of the once sizable Little South Fork population since the late 1980s. Live fluted kidneyshell have not been collected in the Big South Fork since the mid-1980s (Ahlstedtet al.2003-2004, p. 65). In 2010, two individuals were found in Buck Creek and collected for future propagation efforts (McGregor 2010, unpub. data). Live fluted kidneyshell have not been collected in Rock Creek since 1988 (Layzer and Anderson 1992, p. 68). Layzer and Anderson (1992, p. 22) collected fluted kidneyshell at two sites in the West Fork Obey River. A small but recruiting population occurs in the Wolf River, Tennessee, based on 2005-06 sampling (Moleset al.2007, p. 79). This may be the best population remaining in the entire Cumberland River system, where most populations are very restricted in range and are highly imperiled. Given its longevity, small populations of this long-lived species may persist for decades despite total recruitment failure. Therefore, at least 5 of the extant populations may be functionally extirpated (e.g., Horse Lick Creek, Middle Fork Rockcastle River, Little South Fork Cumberland River, Rock Creek, West Fork Obey River).

Population Estimates and Status

Extirpated from both the Cumberland and Tennessee River mainstems, the fluted kidneyshell has been eliminated from approximately 50 percent of the total number of streams from which it was historically known. Population size data gathered during the past decade or two indicate that the fluted kidneyshell is rare in nearly all extant populations, the Clinch River being a notable exception. The fluted kidneyshell is particularly imperiled in Kentucky. Haag and Warren (2004, p. 16) reported that a small, extremely vulnerable population of the fluted kidneyshell may exist in Horse Lick Creek, but atextremely low levels that they were not able to detect. They only collected fresh dead shell material in Horse Lick Creek. The vast reduction of the once sizable Little South Fork population since the late 1980s (Warren and Haag 2005, pp. 1384, 1388-1396) and the tenuous status of the other Cumberland River system populations put the species at risk of total extirpation from that Cumberland River system. In addition, the populations in the Powell River (post-1980) and the Middle Fork (post-1995) and upper North Fork (post-2000) Holston Rivers in Virginia have declined in recent years based on recent survey efforts (Henleyet al.1999, p. 23; Ahlstedtet al.2005, p. 9; Jones and Neves 2007, p. 477; Johnsonet al.in press). Populations of the fluted kidneyshell remain locally abundant in certain reaches of the North Fork Holston River but are reduced in overall range within the river (Ostby and Neves 2005, 2006a, and 2006b, entire; Dinkins 2010a, p. 3-1). Declines in mussel community abundance in the North Fork Holston River have been in the form of several die-offs. The cause for the observed die-offs is unknown (Jones and Neves 2007, p. 479), but may be related to agricultural runoff (Hanlonet al.2009, p. 11).

In summary, the fluted kidneyshell has been eliminated from approximately 50 percent of the total number of streams from which it was historically known. Populations in Buck Creek, Little South Fork, Horse Lick Creek, Powell River, and North Fork Holston River have clearly declined over the past two decades. Based on recent information, the overall population status of the fluted kidneyshell rangewide is declining. A few populations are considered to be viable (e.g., Wolf, Clinch, Little, North Fork Holston Rivers). However, all other populations are of questionable viability, with some on the verge of extirpation (e.g., Horse Lick and Rock Creeks). Newly reintroduced populations will hopefully begin to reverse the overall downward trend of this species.

The fluted kidneyshell was considered a species of special concern by Williamset al.(1993, p. 14), but two decades later is considered endangered in a reassessment of the North American mussel fauna by the Endangered Species Committee of the American Fisheries Society (Butler 2012, pers. comm.). The fluted kidneyshell is listed as a species of Greatest Conservation Need (GCN) in the Kentucky, Tennessee, and Virginia State Wildlife Action Plans (KDFWR 2005; TWRA 2005; VDGIF 2005).

Slabside Pearlymussel Taxonomy and Species Description

The taxonomic status of the slabside pearlymussel (family Unionidae) as a distinct species is undisputed within the scientific community. The species is recognized asLexingtonia dolabelloides(I. Lea, 1840) in the “Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks, Second Edition” (Turgeonet al.1998, p. 35). However, there are currently differing opinions on the appropriate genus to use for the species. Genetic analyses by Boganet al.(unpublished data), as cited by Williamset al.(2008, p. 584), suggests that the type genus ofLexingtonia, Unio subplanaConrad, 1837, is synonymous withFusconaia masoni(Conrad, 1834).Lexingtoniais therefore a junior synonym ofFusconaia,makingLexingtoniano longer available as a valid genus of mussel under the rules of the International Code of Zoological Nomenclature (Williams 2011, pers. comm.). Analyses by Campbellet al.(2005, pp. 141, 143, 147) and Campbell and Lydeard (2012a, pp. 3-6, 9; 2012b, pp. 25-27, 30, 34) suggest that “Lexingtonia” dolabelloides,Fusconaia” barnesiana,and “Pleurobema” gibberumdo not correspond to their currently assigned genera but form a closely related group. Williamset al.(2008, pp. 584-593) and Campbell and Lydeard (2012b, pp. 30, 34) picked the next available genus name fordolabelloides,which appears to bePleuronaia(Frierson 1927). Based on this latest information, we currently considerPleuronaiato be the most appropriate generic name for the slabside pearlymussel.

The following description, biology, and life history of the slabside pearlymussel is taken from data summarized in Parmalee and Bogan (1998, pp. 150-152). The slabside pearlymussel is a moderately sized mussel that reaches about 9 cm (3.5 in) in length. The shape of the shell is subtriangular, and the very solid, heavy valves are moderately inflated. Shell texture is smooth and somewhat shiny in young specimens, becoming duller with age. Shell color is greenish yellow, becoming brownish with age, with a few broken green rays or blotches, particularly in young individuals. Internally, the pseudocardinal teeth are triangular or blade-like in shape. The lateral teeth are slightly curved, with two in the left valve and one in the right valve. The color of the nacre is white, or rarely, straw-colored.

Habitat and Life History

General life history information for the slabside pearlymussel is similar to that given for the fluted kidneyshell above. Samples from approximately 150 shells of the slabside pearlymussel from the North Fork Holston River were thin-sectioned for age determination. The maximum age exceeded 40 years (Grobleret al.2005, p. 65).

The slabside pearlymussel utilizes all four gills as a marsupium for its glochidia. It is thought to have a spring or early summer fertilization period with the glochidia being released during the late summer in the form of conglutinates. Slabside pearlymussel conglutinates have not been described. The slabside pearlymussel's host fishes include 11 species of minnows (popeye shiner,Notropis ariommus;rosyface shiner,N. rubellus;saffron shiner,N. rubricroceus;silver shiner,N. photogenis;telescope shiner,N. telescopus;Tennessee shiner,N. leuciodus;whitetail shiner,Cyprinella galactura;striped shiner,Luxilus chrysocephalus;warpaint shiner,L. coccogenis;white shiner,L. albeolus;and eastern blacknose dace,Rhinichthys atratulus) (Kitchel 1985 and Neves 1991inParmalee and Bogan 1998, pp. 150-152; Jones and Neves 2002, pp. 18-20).

The slabside pearlymussel is primarily a large creek to large river species, inhabiting sand, fine gravel, and cobble substrates in relatively shallow riffles and shoals with moderate current (Parmalee and Bogan 1998, p. 152; Williamset al.2008, p. 590). This species requires flowing, well-oxygenated waters to thrive.

Historical Range and Distribution

Historically, the slabside pearlymussel occurred in the lower Cumberland River mainstem from the vicinity of the Kentucky State line downstream to the the Caney Fork River, Tennessee, and in the Tennessee River mainstem from eastern Tennessee to western Tennessee. Records are known from two Cumberland River tributaries, the Caney Fork [TN] and Red Rivers [KY, TN]. In addition, it is known from 30 Tennessee River system tributaries, including the South Fork Powell River [VA], Powell River [TN, VA], Puckell Creek [VA], Clinch River [TN, VA], North Fork Holston River [TN, VA], Big Moccasin Creek [VA], Middle Fork Holston River [VA], South Fork Holston River [TN], Holston River [TN], Nolichucky River [TN], West Prong Little Pigeon River [TN], French Broad River [TN], Tellico River [TN], Little Tennessee River [TN], Hiwassee River [TN], Sequatchie River [TN],Larkin Fork [AL], Estill Fork [AL], Hurricane Creek [AL], Paint Rock River [AL], Flint River [AL], Flint Creek [AL], Limestone Creek [AL], Elk River [AL, TN], Sugar Creek [AL], Bear Creek [AL, MS], North Fork Creek [TN], Big Rock Creek [TN], Buffalo River [TN], and Duck River [TN] (Gordon and Layzer 1989, entire; Winston and Neves 1997, entire; Parmalee and Bogan 1998, pp. 150-152). The slabside pearlymussel's known historical and current occurrences, by water body and county, are shown in Table 2 below.

Table 2—Known Historical and Current Occurrences for the Slabside Pearlymussel Water body Drainage County State Historical or current Cumberland River Cumberland Davidson, Smith TN Historical. Caney Fork River Cumberland ? TN Historical. Red River Cumberland Logan KY Historical. Red River Cumberland ? TN Historical. South Fork Powell River Tennessee Wise VA Historical. Powell River Tennessee Claiborne TN Historical. Powell River Tennessee Hancock TN Historical and Current. Powell River Tennessee Lee VA Historical and Current. Puckell Creek Tennessee Lee VA Historical. Clinch River Tennessee Hancock TN Historical and Current. Clinch River Tennessee Anderson, Campbell, Claiborne, Knox TN Historical. Clinch River Tennessee Russell, Scott, Tazewell, Wise VA Historical and Current. North Fork Holston River Tennessee Hawkins, Sullivan TN Historical. North Fork Holston River Tennessee Bland, Scott, Smyth, Washington VA Historical and Current. Big Moccasin Creek Tennessee Russell, Scott VA Historical and Current. Middle Fork Holston River Tennessee Smyth, Washington, Wythe VA Historical and Current. South Fork Holston River Tennessee Sullivan TN Historical. Holston River Tennessee ? TN Historical. French Broad River Tennessee Sevier TN Historical. Tennessee River Tennessee Colbert, Jackson, Lauderdale AL Historical. Tennessee River Tennessee Hamilton, Hardin, Knox, Meigs, Rhea TN Historical. Nolichucky River Tennessee Cocke, Greene, Hamblen TN Historical and Current. West Prong Little Pigeon River Tennessee Sevier TN Historical. Tellico River Tennessee Monroe TN Historical. Little Tennessee River Tennessee Monroe TN Historical. Hiwassee River Tennessee Polk TN Historical and Current. Sequatchie River Tennessee Sequatchie TN Historical and Current. Larkin Fork Tennessee Jackson AL Historical and Current. Estill Fork Tennessee Jackson AL Historical and Current. Hurricane Creek Tennessee Jackson AL Historical and Current. Paint Rock River Tennessee Jackson, Madison, Marshall AL Historical and Current. Flint River Tennessee Madison AL Historical. Flint Creek Tennessee Morgan AL Historical. Limestone Creek Tennessee Limestone AL Historical. Elk River Tennessee Limestone AL Historical and Current. Elk River Tennessee Lincoln TN Historical and Current.