Endangered and Threatened Wildlife and Plants; Endangered Species Status for the Fluted Kidneyshell and Slabside Pearlymussel, 59269-59287 [2013-23356]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 78, Number 187 (Thursday, September 26, 2013)]
[Rules and Regulations]
[Pages 59269-59287]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-23356]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2012-0004; 4500030113]
1018-AY06


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for the Fluted Kidneyshell and Slabside Pearlymussel

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
endangered species status under the Endangered Species Act of 1973 
(Act), as amended, for the fluted kidneyshell (Ptychobranchus 
subtentum) and slabside pearlymussel (Pleuronaia dolabelloides). These 
two species are endemic to portions of the Cumberland and Tennessee 
River systems of Alabama, Kentucky, Mississippi, Tennessee, and 
Virginia. The effect of this regulation is to add these species to the 
List of Endangered and Threatened Wildlife and to implement the Federal 
protections provided by the Act for these species.

DATES: This rule is effective on October 28, 2013.

ADDRESSES: This final rule is available on the Internet at https://www.regulations.gov and at https://www.fws.gov/cookeville. Comments and 
materials we received, as well as supporting documentation we used in 
preparing this rule, are available for public inspection at https://www.regulations.gov. All of the comments, materials, and documentation 
that we considered in this rulemaking are available by appointment, 
during normal business hours, at: 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.

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: 

Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act, a 
species warrants protection through listing if it is endangered or 
threatened throughout all or a significant portion of its range. 
Listing a species as an endangered or threatened species can only be 
completed by issuing a rule. Elsewhere in today's Federal Register, we 
designate critical habitat for the fluted kidneyshell and slabside 
pearlymussel.
    This rule lists the fluted kidneyshell and slabside pearlymussel as 
endangered species.
    The basis for our action. Under the Act, we may determine that a 
species is endangered or threatened based on 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. We have determined 
these two mussel species are facing threats based on three of these 
five factors (A, D, and E). Both species have been eliminated from more 
than 50 percent of the streams from which they were historically known, 
and from more than 1,000 river miles (in the Cumberland and Tennessee 
mainstem rivers alone) from which they were historically known due to a 
variety of threats, including impoundments, mining, poor water quality, 
excessive sedimentation, and environmental contaminants.
    Peer review and public comment. We sought comments from independent 
specialists to ensure that our determination is based on scientifically 
sound data, assumptions, and analyses. We invited these peer reviewers 
to comment on our listing proposal. We also considered all comments and 
information we received during the comment period.

Previous Federal Actions

    We proposed listing the fluted kidneyshell and slabside 
pearlymussel as endangered under the Act with critical habitat on 
October 4, 2012 (77 FR 60804). For a complete history of all Federal 
actions related to these species, please refer to the October 4, 2012, 
proposed listing and critical habitat rule. Elsewhere in today's 
Federal Register, we designate critical habitat

[[Page 59270]]

for the fluted kidneyshell and slabside pearlymussel under the Act.

Background

Introduction

    North American mussel fauna are more biologically diverse than 
anywhere else in the world, and historically numbered around 300 
species (Williams et al. 1993, p. 6). Mussels are in decline, however, 
and in the past century have become more imperiled than any other group 
of organisms (Williams et al. 2008, p. 55). Approximately 72 percent of 
North America's mussel species are considered vulnerable to extinction 
or possibly extinct (Williams et 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 (Neves et 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 (Neves et al. 1997, p. 60). The fluted 
kidneyshell and slabside pearlymussel, 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, State and Federal 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 northeastern Alabama, then flows across northern 
Alabama before turning north and flowing through western Tennessee into 
Kentucky and empties into the Ohio River. The greater 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 (Turgeon et 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 Williams et 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. For a complete description of the species, please refer 
to the October 4, 2012, proposed listing and critical habitat rule (77 
FR 60804).

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 (Strayer et al. 2004, pp. 
430-431). Adults are filter feeders and generally orient themselves on 
or near the substrate surface to take in food and oxygen from the water 
column. Adult mussels also can obtain their food by deposit feeding, 
pulling in food from the sediment and its interstitial (pore) water, 
and pedal- (foot-) feeding directly from the sediment (Yeager et al. 
1994, pp. 217-221; Vaughn and Hakenkamp 2001, pp. 1432-1438; Nichols et 
al. 2005, pp. 90-93). Juveniles typically burrow completely beneath the 
substrate surface and are deposit or pedal feeders. Until the 
structures for filter feeding are more fully developed, food particles 
that adhere to the foot while it is extended outside the shell and are 
moved inside the shell for ingestion, until the structures for filter 
feeding are more fully developed (Yeager et al. 1994, pp. 200-221; 
Gatenby et al. 1996, p. 604).
    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. Reported longevity of the 
fluted kidneyshell ranges from 26 to 55 years (Henley et 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. It has been 
hypothesized that pheromones might trigger synchronous sperm release 
among males, because all fertilization observed by fluted kidneyshell 
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 
short (5 days or less) fertilization period of the fluted kidneyshell 
is thought to occur sometime in late summer or early fall 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 membrane-bound packets 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 specific host fish(es) 
quickly in

[[Page 59271]]

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. For example, 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; Barnhart et al. 2008, p. 377; Williams et al. 
2008, p. 628). Insects are common food items of many stream fishes, 
including the fluted kidneyshell's host fishes, such as 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 juvenile mussels 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 (Williams et 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. The fluted kidneyshell's 
known historical and current occurrences, by water body and county, are 
shown in Table 1 below (data collected from Gordon and Layzer 1989, 
entire; Winston and Neves 1997, entire; Parmalee and Bogan 1998, pp. 
204-205; Layzer and Scott 2006, p. 481).

          Table 1--Known Historical (Prior to 1980) and Current Occurrences for the Fluted Kidneyshell
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          Water body                 Drainage            County         State         Historical or current
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Cumberland River..............  Cumberland.......  McCreary,          KY        Historical.
                                                    Pulaski, Russell.
Cumberland River..............  Cumberland.......  Stewart..........  TN        Historical.
Middle Fork Rockcastle River..  Cumberland.......  Jackson..........  KY        Historical and Current
Horse Lick Creek..............  Cumberland.......  Jackson,           KY        Historical and Current.
                                                    Rockcastle.
Rockcastle River..............  Cumberland.......  Laurel, Pulaski,   KY        Historical.
                                                    Rockcastle.
Buck Creek....................  Cumberland.......  Pulaski..........  KY        Historical and Current.
Big South Fork Cumberland       Cumberland.......  McCreary, Pulaski  KY        Historical and Current.
 River.
Big South Fork Cumberland       Cumberland.......  Fentress, Morgan,  TN        Historical and Current.
 River.                                             Scott.
Rock Creek....................  Cumberland.......  McCreary.........  KY        Historical and Current.
Little South Fork Cumberland    Cumberland.......  McCreary, Wayne..  KY        Historical and Current.
 River.
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,         TN        Historical and Current.
                                                    Hancock.
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,          TN        Historical.
                                                    Claiborne,
                                                    Grainger, Roane,
                                                    Union.
Clinch River..................  Tennessee........  Russell, Scott,    VA        Historical and Current.
                                                    Tazewell, Wise.
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,      VA        Historical and Current.
                                                    Smyth,
                                                    Washington.
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,          TN        Historical.
                                                    Hamblen,
                                                    Jefferson, Knox.
French Broad River............  Tennessee........  ?................  TN        Historical.
Tennessee River...............  Tennessee........  Colbert, Jackson,  AL        Historical.
                                                    Lauderdale.
Tennessee River...............  Tennessee........  Decatur, Knox,     TN        Historical.
                                                    Meigs, Rhea.
Nolichucky River..............  Tennessee........  Greene...........  TN        Historical and Current.

[[Page 59272]]

 
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.
Boiling Fork Creek............  Tennessee........  Franklin.........  TN        Historical.
Shoal Creek...................  Tennessee........  Lauderdale,        AL        Historical.
                                                    Limestone.
Duck River....................  Tennessee........  Bedford,           TN        Historical and Current.
                                                    Marshall, Maury.
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 (individuals that are deceased, but still have flesh attached 
to the shell) have been collected since circa 1980. This criterion 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 this species (26-55 years), they are still thought to 
occur in these areas. 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. Based on 
these criteria, we consider 17 of 40 populations of fluted kidneyshell 
to be extant. Therefore, the fluted kidneyshell has been eliminated 
from more than 50 percent of streams from which it was historically 
known.
    Several 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 
(Ostby et 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 
translocated (transferred from one location to another) from the Clinch 
River into three sites in the upper Duck River and into two sites in 
the Nolichucky River by Tennessee Wildlife Resource Agency (TWRA) 
biologists (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 et al. 2011, p. 18). The individuals 
collected appeared in good condition and had grown noticeably since 
their release (as evidenced by external shell marks) (Hubbs 2011, 
unpubl. data). Evidence that the reintroduced population of fluted 
kidneyshell was recruiting was documented in 2012, when a young 
unmarked sub-adult individual was found in a muskrat midden (pile or 
mound of shells) near Lillard's Mill in the Duck River (Hubbs 2012, 
pers. comm.). 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). Both reintroduction sites in the Nolichucky River have 
retained ``large numbers of live individuals'' (Hubbs 2012, pers. 
comm.). It is not known if the 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. The only population of 
the fluted kidneyshell known to be large, stable, and viable is in the 
Clinch River, but it is 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

[[Page 59273]]

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). Henley et 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) (Hanlon et al. 
2009, pp. 15-17). Petty et 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 (Johnson et al. 
2012, p. 96). Ostby et 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 
(Ahlstedt et 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 2005-2006 sampling (Moles et 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. Given the reports presented above, at least five 
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 at extremely 
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 according to recent survey efforts 
(Henley et al. 1999, p. 23; Ahlstedt et al. 2005, p. 9; Jones and Neves 
2007, p. 477; Johnson et al. 2012, pp. 94-96). 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 
they are likely related to agricultural impacts (Hanlon et al. 2009, p. 
11).
    In summary, the fluted kidneyshell has been eliminated from more 
than 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 Williams et al. (1993, p. 14), but two decades later is now 
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.). Further, 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 as Lexingtonia dolabelloides (I. 
Lea, 1840) in the ``Common and Scientific Names of Aquatic 
Invertebrates from the United States and Canada: Mollusks, Second 
Edition'' (Turgeon et al. 1998, p. 35). However, there are currently 
differing opinions on the appropriate genus to use for the species. 
Genetic analyses by Bogan et al. (unpublished data), as cited by 
Williams et al. (2008, p. 584), suggest that the type species of 
Lexingtonia, Unio subplana Conrad, 1837, is synonymous with Fusconaia 
masoni (Conrad, 1834). Lexingtonia is therefore a junior synonym of 
Fusconaia (Williams 2011, pers. comm.). Analyses by Campbell et 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'' gibberum do not correspond 
to their currently assigned genera but form a closely related group. 
Williams et al. (2008, pp. 584-593) and Campbell and Lydeard (2012b, 
pp. 30, 34) picked the next available genus name for dolabelloides, 
which appears to be Pleuronaia (Frierson 1927). Based on this latest 
information, we currently consider Pleuronaia to 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)

[[Page 59274]]

in length. The shape of the shell is subtriangular, and the very solid, 
heavy valves are moderately inflated. For a complete description of the 
species, please refer to the October 4, 2012, proposed listing and 
critical habitat rule (77 FR 60804).

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 (Grobler et 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 1991 in Parmalee 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; Williams et 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 Caney Fork River, Tennessee, and in the Tennessee 
River mainstem from eastern Tennessee to western Tennessee. The 
slabside pearlymussel's known historical and current occurrences, by 
water body and county, are shown in Table 2 below (data from Gordon and 
Layzer 1989, entire; Winston and Neves 1997, entire; Parmalee and Bogan 
1998, pp. 150-152).

         Table 2--Known Historical (Prior to 1980) and Current Occurrences for the Slabside Pearlymussel
----------------------------------------------------------------------------------------------------------------
                                                                                                 Historical or
           Water body                  Drainage             County               State              current
----------------------------------------------------------------------------------------------------------------
Cumberland River................  Cumberland........  Davidson, Smith...  TN................  Historical.
Rock Creek......................  Cumberland........  McCreary..........  KY................  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,           TN................  Historical.
                                                       Campbell,
                                                       Claiborne, Knox.
Clinch River....................  Tennessee.........  Russell, Scott,     VA................  Historical and
                                                       Tazewell, Wise.                         Current.
North Fork Holston River........  Tennessee.........  Hawkins, Sullivan.  TN................  Historical.
North Fork Holston River........  Tennessee.........  Bland, Scott,       VA................  Historical and
                                                       Smyth, Washington.                      Current.
Big Moccasin Creek..............  Tennessee.........  Russell, Scott....  VA................  Historical and
                                                                                               Current.
Middle Fork Holston River.......  Tennessee.........  Smyth, Washington,  VA................  Historical and
                                                       Wythe.                                  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,   AL................  Historical.
                                                       Lauderdale.
Tennessee River.................  Tennessee.........  Hamilton, Hardin,   TN................  Historical.
                                                       Knox, Meigs, Rhea.
Nolichucky River................  Tennessee.........  Cocke, Greene,      TN................  Historical and
                                                       Hamblen.                                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.
Spring Creek....................  Tennessee.........  Polk..............  TN................  Historical.
Sequatchie River................  Tennessee.........  Sequatchie........  TN................  Historical and
                                                                                               Current.
Crow Creek......................  Tennessee.........  Jackson...........  AL................  Historical.
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,   AL................  Historical and
                                                       Marshall.                               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.
Elk River.......................  Tennessee.........  Coffee, Franklin,   TN................  Historical.
                                                       Moore.
Sugar Creek.....................  Tennessee.........  Limestone.........  AL................  Historical.
Bear Creek......................  Tennessee.........  Colbert...........  AL................  Historical and
                                                                                               Current.
Bear Creek......................  Tennessee.........  Tishomingo........  MS................  Historical and
                                                                                               Current.

[[Page 59275]]

 
Duck River......................  Tennessee.........  Bedford, Hickman,   TN................  Historical and
                                                       Marshall, Maury.                        Current.
Duck River......................  Tennessee.........  Coffee............  TN................  Historical.
North Fork Creek................  Tennessee.........  Bedford...........  TN................  Historical.
Big Rock Creek..................  Tennessee.........  Marshall..........  TN................  Historical.
Buffalo River...................  Tennessee.........  Humphreys, Perry..  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.

    Based on collections made in the early 1900s, the slabside 
pearlymussel was historically fairly widespread and common in many 
Cumberlandian Region streams. However, its decline in certain streams 
may have begun before European colonization. The slabside pearlymussel 
was considered rare by mussel experts as early as 1970 (Stansbery 1971, 
p. 13), which represents the first attempt to compile such a list. 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 slabside pearlymussel, as for 
the fluted kidneyshell, are generally considered extant (current) if 
live individuals or fresh dead specimens have been collected since 
circa 1980. This criterion 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 this species (approximately 
40 years), they are still thought to occur in these areas.
    Where two or more stream populations occur contiguously with no 
absolute barriers (e.g., large impoundments) or long reaches of 
unoccupied habitat, they are considered to represent a single 
population segment. The Paint Rock River system (including Larkin Fork, 
Estill Fork, and Hurricane Creek) is considered a single population 
segment or cluster but it occurs only in the lower mile or so of the 
three tributary streams. Accordingly, we consider 13 of 30 populations 
of the slabside pearlymussel to be extant. The slabside pearlymussel 
has been eliminated from more than 50 percent of streams from which it 
was historically known.
    The extant occurrences in the Tennessee River system represent 11 
isolated populations. Population size data gathered during the past two 
decades indicate that the slabside pearlymussel is rare (experienced 
surveyors may find four or fewer specimens per site of occurrence) in 
about half of its extant populations. Only a few individuals have been 
found in the Powell River since 1988; therefore, this population is 
considered extremely rare (Ahlstedt et al. 2005, p. 9). In 2009, four 
individuals were collected in the Powell River (Johnson et al. 2010, p. 
39). A single live individual was found in 2006 in Big Moccasin Creek, 
Virginia (Ostby et al. 2006, p. 3). The slabside pearlymussel is 
uncommon to rare in the Clinch River, with only a few individuals found 
per given survey effort (Ahlstedt et al. 2005, p. 8). In 2002, Eckert 
and Pinder (2010, pp. 23-30) observed 2 individuals in quantitative 
samples and 13 individuals in semi-quantitative samples in the Clinch 
River at Cleveland Island; 6 years later, they collected 1 individual 
in quantitative samples and 5 individuals in semi-quantitative samples 
at the same site. In 2005, approximately 20 individuals were found near 
Harms Mill (one of five sites surveyed) in the Elk River, Tennessee, 
and 13 individuals (at 2 of 5 survey sites, spanning approximately 48 
rkm (30 rmi)) were found in 2008 (Howard 2009, pers. comm.; Tennessee 
Valley Authority (TVA) 2009, p. 59). In 2002, one live individual was 
found in the Hiwassee River (Ahlstedt 2003, p. 3). The slabside 
pearlymussel was last found in the Sequatchie River 2 miles north of 
Dunlap, Tennessee in 1980 (Hatcher and Ahlstedt 1982, p. 9). A small 
population is limited to Bear Creek in Mississippi, the only occurrence 
in that State (Jones 2012, pers. comm.). In 2009, TVA collected 9 
individuals at one site in Bear Creek (TVA 2010, p. 69). This 
population is recruiting, as evidenced by collection of the shell 
remains of a fresh dead juvenile in 2011 (Johnson 2011, pers. comm.). 
Given its longevity, small populations of this long-lived species may 
persist for decades, long after total recruitment failure. The species 
has undergone decline in the North and Middle Forks of the Holston 
River (Jones and Neves 2005, pp. 8-9). This is especially true for the 
North Fork, where the species has been nearly eliminated (Hanlon 2006, 
unpub. data). The cause for the observed die-offs is unknown (Jones and 
Neves 2007, p. 479). Ostby et al. (2010, pp. 16-20) observed eight 
individuals in qualitative surveys at one site, but did not observe the 
species in quantitative surveys in the Upper North Fork Holston River. 
Slabside pearlymussels have declined at three of four survey sites on 
the Middle Fork Holston River (Henley 2011, pers. comm.). A single 
valve of a fresh dead specimen was found in the Nolichucky River in 
2011 (Dinkins 2010b, p. 2-1). In 2011, TVA collected one living 
individual in the Buffalo River (Wales 2012, pers. comm.).
    The Duck and Paint Rock Rivers appear to have the best populations 
remaining rangewide based on population size and the evidence of recent 
recruitment. The slabside pearlymussel is found at numerous sites 
throughout the Duck River, and is found at numerous sites within a 72-
rkm (45-rmi) reach of the Paint Rock River (Schilling and Williams 
2002, p. 409; Ahlstedt et al. 2004, p. 84; Fobian et al. 2008, pp. 15-
16; Hubbs 2012, pers. obs.). The slabside pearlymussel was reported 
present but rare at four of six sites sampled in the Duck River during 
a 2010 quantitative survey (Hubbs et al. 2011, pp. 19-25).

Population Estimates and Status

    Current status information for most of the 13 extant populations is 
available from recent survey efforts (sometimes annually) and other 
field studies. Comprehensive surveys have taken place in the Middle and 
North Forks Holston River, Paint Rock River, and Duck River in the past 
several years. Based on this information, the overall population of the 
slabside pearlymussel appears to be declining rangewide, with 
relatively good numbers and apparent viability in just two streams 
(Duck and Paint Rock Rivers). Two of the four largest populations in 
the mid-1990s have recently experienced drastic recent

[[Page 59276]]

declines (i.e., North and Middle Forks Holston Rivers), especially in 
the North Fork. Most of the other populations are of questionable 
viability and may be on the verge of extirpation (e.g., Powell and 
Hiwassee Rivers; Big Moccasin Creek).
    Populations of the slabside pearlymussel appear to be declining 
rangewide and have been extirpated from more than 50 percent of the 
streams from which the species was historically known to occur. The 
slabside pearlymussel was considered threatened by Williams et al. 
(1993, p. 13), but is now 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.). Further, the 
slabside pearlymussel is listed as a species of Greatest Conservation 
Need (GCN) in the Alabama, Mississippi, Tennessee, and Virginia State 
Wildlife Action Plans (Alabama Department of Conservation and Natural 
Resources, Division of Wildlife and Freshwater Fisheries, 2005; KDFWR 
2005; Mississippi Department of Wildlife, Fisheries and Parks 2005; 
TWRA 2005; VDGIF 2005).

Summary of Comments and Recommendations

    In the proposed rule published on October 4, 2012 (77 FR 60804), we 
requested that all interested parties submit written comments on the 
proposed rule to list the fluted kidneyshell and slabside pearlymussel 
by December 3, 2012. We also contacted appropriate Federal and State 
agencies, scientific experts and organizations, and other interested 
parties and invited them to comment on the proposal. Newspaper notices 
inviting general public comment were published in newspapers covering 
all affected counties in Alabama, Kentucky, Mississippi, Tennessee, and 
Virginia. During that comment period, we received one request for a 
public hearing in Virginia. We subsequently reopened the public comment 
period for the October 4, 2012, proposed rule; made available the draft 
economic analysis for the proposed critical habitat designation; and 
announced a public informational session and public hearing on the 
proposal, which we held on May 14, 2013 (78 FR 25041; April 29, 2013).
    During the two comment periods for the proposed rule, we received 
seven comment letters in response to the proposed determination of 
endangered species status for the fluted kidneyshell and slabside 
pearlymussel: Two from peer reviewers, one from a Federal agency, and 
four from organizations or individuals. We did not receive any comments 
from State agencies. Four of the seven commenters supported the 
proposed rule. All substantive information provided during the comment 
period has either been incorporated directly into this final 
determination or is addressed below.

Peer Reviewer Comments

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinions from eight knowledgeable 
individuals with scientific expertise that included familiarity with 
the two mussels and their habitats, biological needs, and threats. We 
received responses from two of the peer reviewers.
    We reviewed all comments we received from the peer reviewers for 
substantive issues and new information regarding the listing of the two 
mussels. The peer reviewers generally concurred with our conclusions 
and provided additional information on taxonomic classification, life 
history, current distribution, and threats. Peer reviewers provided 
minor edits and comments related to the listing of these species, which 
we incorporated into the final rule as appropriate. The substantive 
comments we received from one peer reviewer on the critical habitat 
designation are addressed in the final critical habitat rule published 
elsewhere in today's Federal Register.

Federal Agency Comments

    (1) Comment: The U.S. Department of Agriculture, Natural Resources 
Conservation Service (NRCS) in Kentucky would like to explore 
opportunities to focus conservation practices, including the Wildlife 
Habitat Incentives Program (WHIP) and the Environmental Quality 
Incentives Program, on water quality improvement and restoration in any 
areas designated as critical habitat for the fluted kidneyshell and 
other aquatic organisms.
    Our Response: The Service concurs that Farm Bill practices 
implemented by the NRCS can improve water quality and benefit rare 
aquatic species. We will continue to work with NRCS to identify aquatic 
habitats for rare aquatic species that would benefit from conservation 
practices on private lands.

Public Comments

    (2) Comment: Under the Multi-District Litigation (MDL) settlement 
agreement, the Service has failed to preserve and consider the 
``warranted but precluded'' finding for this listing decision. Further, 
the Service did not request comments on its decision to exclude this 
finding, and does not in the proposed rule request public comment on 
whether a ``warranted but precluded'' finding might be appropriate. The 
failure to preserve the ``warranted by precluded'' finding negates 
important conservation mechanisms for the mussels by removing 
incentives for State and private conservation actions designed to avoid 
the need for listing.
    Our Response: The United States Court of Appeals for the District 
of Columbia Circuit has recently spoken to these issues. Safari Club 
International moved to intervene in the MDL, arguing in part that the 
settlement agreements, ``establish an illegal procedure--the 
elimination of the Service's statutory authority to find that a 
proposal to list a species is warranted but precluded by higher 
priorities.'' On January 4, 2013, the United States Court of Appeals 
for the District of Columbia Circuit affirmed the District Court's 
holding that Safari Club International lacked standing to challenge 
these agreements (see Safari Club v. Salazar, 704 F.3d 972 (D.C. Cir. 
2013)). Among other things, the Court held that neither the Act nor the 
implementing regulations require the Service to invite comment when it 
makes a warranted-but-precluded finding. Responding to the concern that 
the failure to preserve the ``warranted by precluded'' finding negates 
important conservation mechanisms, the Court held there is nothing to 
indicate that Congress intended the Act ``to allow [the Service] to 
delay commencing the rulemaking process for any reason other than the 
existence of pending or imminent proposals to list species subject to a 
greater degree of threat [that] would make allocation of resources to 
such a petition unwise.''
    Further, even if additional time for conservation measures was a 
permissible reason for delaying the rulemaking process, we do not 
believe failure to preserve the ``warranted by precluded'' finding 
negates important conservation mechanisms for the mussels by removing 
incentives for State and private conservation actions designed to avoid 
the need for listing. As we discussed in the proposed listing rule (77 
FR 60804; see Previous Federal Actions), the fluted kidneyshell has 
been a formal candidate for listing under the Act since 1999, and the 
slabside pearlymussel has been a formal candidate for listing since 
1984. The MDL settlement agreements now provide predictability for 
stakeholders and local communities. Prior to the settlement agreements, 
stakeholders were unsure when the Service might pursue a listing 
determination on a candidate species. The settlements have

[[Page 59277]]

allowed the Service to establish and make available to the public a 
multi-year schedule for listing determinations on our candidate 
species. Stakeholders know in advance, in some cases years in advance, 
when we will be reviewing these candidates to determine whether a 
listing proposal is still warranted. The settlements have also served 
to encourage proactive conservation efforts by landowners, industry 
groups, local communities, and government agencies. Sometimes proactive 
conservation efforts can make a listing under the Act no longer 
necessary. Candidate conservation agreements with assurances (CCAAs) 
can also be developed and permitted to provide regulatory assurances to 
participating landowners in the event that listing is still warranted. 
Conservation efforts developed by stakeholders may also be rolled into 
habitat conservation plans that provide predictability and compliance 
with the Act for landowners, industry groups, or local communities.
    (3) Comment: The Service published a proposed rule that had not 
undergone peer review, thereby not necessarily reflecting sound 
science, as required by section 4 of the Act and as required under 
section 515(b)(2)(A) of the Information Quality Act. Rather than 
conducting peer review prior to publication of the proposed rule, which 
would allow the public to view a fully scientifically vetted proposal, 
the Service opted to conduct peer review contemporaneously with the 
public comment period. Additionally, there is no indication that the 
public will have an opportunity to review and comment on the rule as 
informed by peer review, which is troubling due to the Service relying 
on decades-old data (e.g., concluding a population to be extant if 
found post-1980).
    Our Response: In accordance with our peer review policy published 
on July 1, 1994 (59 FR 34270), we solicited expert opinion from eight 
knowledgeable individuals with scientific expertise that included 
familiarity with the two mussels and their habitats, biological needs, 
and threats. In keeping with our policy, we contacted these peer 
reviewers when the proposed rule was published in the Federal Register. 
We received responses from two of the peer reviewers. We posted all of 
the comments we received on the October 4, 2012, proposed rule to list 
the fluted kidneyshell and slabside pearlymussel as endangered under 
the Act with critical habitat (77 FR 60804) on the Internet at https://www.regulations.gov under Docket No. FWS-R4-ES-2012-0004.
    We reviewed all comments we received from the peer reviewers and 
others for substantive issues and new information regarding the listing 
of both mussels. The peer reviewers generally concurred with our 
conclusions and provided additional information on taxonomic 
classification, life history, current distribution, and threats. Peer 
reviewers provided minor edits and comments related to the listing of 
these species, which we incorporated into the final rule as 
appropriate.
    Further, section 515(b)(2)(A) of the Information Quality Act 
requires that each Federal agency issue guidelines ensuring and 
maximizing the quality, objectivity, utility, and integrity of 
information (including statistical information) disseminated by the 
agency. The Service's guidelines, which are updated as of June 2012, 
are available on the Internet at: https://www.fws.gov/informationquality/topics/IQAguidelines-final82307.pdf.
    (4) Comment: The proposed rule relies on questionable factual and 
scientific bases by considering populations of the two species to be 
``extant'' if specimens have been observed since 1980, a period of over 
30 years. This notion appears scientifically untested and misguided 
given the Service's conclusion that the species have been eliminated 
from over 50 percent of their habitat. The Service's asserted basis for 
relying on dated information is circular, and scientific 
determinations, such as whether a species is extant or endangered, 
should be based on current, empirical data that are measurable and 
repeatable.
    Our Response: We are required, by statute and regulation, to base 
our determinations solely on the basis of the best scientific and 
commercial data available. 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 
mussel collections were conducted in the 1980s in the Cumberland and 
Tennessee River systems; fewer collections were conducted post-1980. 
Although many of these reaches have not been surveyed since the 1980s, 
due to the reported longevity of these species (26-55 years; Henley et 
al. 2002, p. 19; Davis and Layzer 2012, p. 92), it is likely they still 
occur in those reaches.
    Approximately 50 percent of the habitat for these species has been 
eliminated, most of which is due to impoundment, and we have not 
considered impounded river reaches to be ``extant'' populations.
    (5) Comment: The preamble of the proposed rule relies in part on 
climate change as a factor supporting the listing decision and relies 
on unsubstantiated claims about the effects of climate change on the 
species. Additionally, such attenuated assertions of endangerment could 
be used to justify the listing of almost any species and do not 
constitute scientific evidence of endangerment.
    Our Response: There is a growing concern that climate change may 
lead to increased frequency of severe storms and droughts (McLaughlin 
et al. 2002, p. 6074; Cook et al. 2004, p. 1015; Golladay et al. 2004, 
p. 504). Specific effects of climate change to mussels, their habitat, 
and their fish hosts could include changes in stream temperature 
regimes and changes in the timing and levels of precipitation, causing 
more frequent and severe floods and droughts. The present conservation 
status, complex life histories, and specific habitat requirements of 
mussels suggest that they may be quite sensitive to the effects of 
climate change (Hastie et al. 2003, p. 45).
    Increases in temperature and reductions in flow can also lower 
dissolved oxygen levels in interstitial habitats, a condition that can 
be lethal to juveniles (Sparks and Strayer 1998, pp. 131-133). Even 
small increases in temperature can cause reductions in the survival of 
freshwater mussel glochidia and juveniles, and temperatures currently 
encountered in the temperate United States during summers are close to 
or above the upper thermal tolerances of early life stages of 
freshwater mussels (Pandolfo et al. 2010, pp. 965, 967). Effects to 
mussel populations from these environmental changes could include 
reduced abundance and biomass, altered species composition, and reduced 
host fish availability (Galbraith et al. 2010, pp. 1180-1182).
    During high flows, flood scour can dislodge mussels, potentially 
causing them to be injured, buried, swept into unsuitable habitats, or 
stranded and perish when flood waters recede (Vannote and Minshall 
1982, p. 4105; Tucker 1996, p. 435; Hastie et al. 2001, pp. 107-115; 
Peterson et al. 2011, unpaginated). We have deleted several ``may'' 
statements regarding how climate change could impact freshwater 
mussels. We have added in citations regarding studies on how increased 
temperature impacts larval and juvenile mussels (see Factor E for a 
more detailed discussion).
    (6) Comment: The proposed rule sets forth an overbroad statement of 
the types of activities that could constitute a ``take'' of these 
species. For example,

[[Page 59278]]

the rule identifies, ``unauthorized modification of the channel, 
substrate, temperature, or water flow of any stream or water body in 
which these species are known to occur'' and ``unauthorized discharge 
of chemicals or fill material into any waters in which the fluted 
kidneyshell and slabside pearlymussel are known to occur.'' 
Additionally, the Service fails to include the key qualification that 
an action must [italics added by commenter for emphasis] proximately 
cause actual death or injury to a species in order to qualify as 
``harm'' within the meaning of ``take.''
    Our Response: Section 9 of the Act and our regulations prohibit the 
take of endangered and threatened species, with certain exceptions. 
Take is defined by the Act as to harass, harm, pursue, hunt, shoot, 
wound, kill, trap, capture, or collect, or to attempt to engage in any 
such conduct. Harm is defined in our regulations at 50 CFR 17.3 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. Also 
in our regulations at 50 CFR 17.3, harass is defined as intentional or 
negligent actions that create the likelihood of injury to listed 
species to such an extent as to significantly disrupt normal behavioral 
patterns which include, but are not limited to, breeding, feeding or 
sheltering.
    Examples of chemical spills and their effects on mussels, including 
the fluted kidneyshell, are provided in the Chemical Contaminants 
section under the Factor E discussion below. Questions regarding 
whether specific activities would constitute a violation of section 9 
of the Act should be directed to the Ecological Services Field Office 
in the State where the activity would take place.

Summary of Changes From Proposed Rule

    As a result of the comments we received during the public comment 
periods (see above), we made the following changes to this final 
listing rule:
    (1) We revised the description of the Tennessee River in the 
introduction.
    (2) We added life-history information to the fluted kidneyshell 
background section.
    (3) We updated the current status of the fluted kidneyshell to 
reflect recent evidence of recruitment.
    (4) We revised the taxonomy section for the slabside pearlymussel.
    (5) We revised the current and historical occurrences for both the 
fluted kidneyshell and slabside pearlymussel.
    (6) We have deleted several ``may'' statements regarding how 
climate change could impact freshwater mussels and added in citations 
regarding studies on how increased temperature impacts larval and 
juvenile mussels (see Factor E for a more detailed discussion).
    We note here, however, that none of these changes affected our 
determinations for these two species, and as proposed, in this rule we 
are listing both the fluted kidneyshell and slabside pearlymussel as 
endangered species.

Summary of Factors Affecting the Species

    Section 4 of the Act, and its implementing regulations at 50 CFR 
part 424, set forth the procedures for adding species to the Federal 
Lists of Endangered and Threatened Wildlife and Plants. Under section 
4(a)(1) of the Act, we may list a species based on any of the following 
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; and (E) other natural or manmade factors affecting its 
continued existence. Listing actions may be warranted based on any of 
the above factors, singly or in combination. Each of these factors is 
discussed below.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    The decline of the fluted kidneyshell and slabside pearlymussel in 
the Cumberlandian Region and other mussel species in the eastern United 
States is primarily the result of habitat loss and degradation. Chief 
among the causes of decline are impoundments, gravel and coal mining, 
sedimentation, water pollution, and stream channel alterations (Neves 
1993, pp. 4-5; Williams et al. 1993, p. 7; Neves et al. 1997, pp. 60-
78).
Impoundments
    Impoundments result in the dramatic modification of riffle and 
shoal habitats and the resulting loss of mussel resources, especially 
in larger rivers. Impoundment impacts are most profound in riffle and 
shoal areas, which harbor the largest assemblages of mussel species, 
including the fluted kidneyshell and slabside pearlymussel. Mussels are 
relatively immobile and, therefore, require a stable substrate to 
survive and reproduce, and are particularly susceptible to channel 
instability (Neves et al. 1997, p. 23) and alteration in the dynamic 
processes involved in maintaining stream stability. Dams interrupt most 
of a river's ecological processes by modifying flood pulses; 
controlling impounded water elevations; altering water flow, sediments, 
nutrients, energy inputs, and outputs; increasing depth; decreasing 
habitat heterogeneity; and decreasing bottom stability due to 
subsequent sedimentation. In addition, dams can also seriously alter 
downstream water quality and riverine habitat and negatively impact 
tailwater mussel populations. These changes include thermal alterations 
immediately below dams; changes in channel characteristics, habitat 
availability, and flow regime; daily discharge fluctuations; increased 
silt loads; and altered host fish communities. For these above-
mentioned reasons, the reproductive process of riverine mussels is 
generally disrupted by impoundments, making them unable to successfully 
reproduce and recruit under reservoir conditions. Coldwater releases 
from large, non-navigational dams and scouring of the river bed from 
highly fluctuating, turbulent tailwater flows have also been implicated 
in the demise of mussel faunas.
    The damming of rivers has been a major factor contributing to the 
demise of mussels (Bogan 1993, p. 604). Dams eliminate or reduce river 
flow within impounded areas, trap silts and cause sediment deposition, 
alter water temperature and dissolved oxygen levels, change downstream 
water flow and quality, affect normal flood patterns, and block 
upstream and downstream movement of mussels and their host fishes 
(Bogan 1993, p. 604; Vaughn and Taylor 1999, pp. 915-917; Watters 1999, 
pp. 261-264; McAllister et al. 2000, p. iii; Marcinek et al. 2005, pp. 
20-21). Below dams, mollusk declines are associated with changes and 
fluctuation in flow regime, scouring and erosion, reduced dissolved 
oxygen levels, reduced food availability, water temperature alteration, 
and changes in resident fish assemblages (Williams et al. 1993, p. 7; 
Neves et al. 1997, pp. 63-64; Watters 1999, pp. 261-264; Marcinek et 
al. 2005, pp. 20-21; Moles and Layzer 2008, p. 220). Because rivers are 
linear systems, these alterations can cause mussel declines for many 
miles below the dam (Moles and Layzer 2008, p. 220; Vaughn and Taylor 
1999, p. 916).
    Population losses due to impoundments have probably contributed 
more to the decline of the

[[Page 59279]]

fluted kidneyshell, slabside pearlymussel, and other Cumberlandian 
Region mussels than has any other single factor. The majority of the 
Cumberland and Tennessee River mainstems and many of their largest 
tributaries are now impounded and, therefore, are unsuitable for 
Cumberlandian Region mussels. For example, approximately 90 percent of 
the 904-river-kilometer (rkm) (562-river-mile (rmi)) length of the 
Cumberland River downstream of Cumberland Falls is either impounded 
(three locks and dams and Wolf Creek Dam) or otherwise adversely 
impacted by coldwater discharges from Wolf Creek Dam. Other major U.S. 
Army Corps of Engineers (Corps) impoundments on Cumberland River 
tributaries (e.g., Obey River, Caney Fork) have inundated over 161 rkm 
(100 rmi) of riverine habitat for the fluted kidneyshell and the 
slabside pearlymussel. Layzer et al. (1993, p. 68) reported that 37 of 
the 60 mussel species present in the Caney Fork River pre-impoundment 
have been extirpated. By 1971, approximately 3,700 rkm (2,300 rmi) 
(about 20 percent) of the Tennessee River and its tributaries with 
drainage areas of 65 square rkm (25 square rmi) or greater were 
impounded by the TVA (TVA 1971, p. 5). The subsequent completion of 
additional major impoundments on tributary streams (e.g., Duck River in 
1976, Little Tennessee River in 1979) significantly increased the total 
river kilometers impounded behind the 36 major dams in the Tennessee 
River system.
    Given projected human population increases and the need for 
municipal water supply, other proposals for small impoundment 
construction are likely in the future within the Cumberland and 
Tennessee River systems.
Mining and Commercial Navigation
    Instream gravel mining has been implicated in the destruction of 
mussel populations. Negative impacts associated with gravel mining 
include stream channel modifications (e.g., altered habitat, disrupted 
flow patterns, sediment transport), water quality modifications (e.g., 
increased turbidity, reduced light penetration, increased temperature), 
macroinvertebrate population changes (e.g., elimination, habitat 
disruption, increased sedimentation), and changes in fish populations 
(e.g., impacts to spawning and nursery habitat, food web disruptions) 
(Kanehl and Lyons 1992, pp. 26-27).
    Gravel mining activities negatively impact the habitat of the 
fluted kidneyshell in Buck Creek, one of the few remaining populations 
of this species in the entire Cumberland River system. Gravel mining 
activities also negatively impact the habitat of the slabside 
pearlymussel in the Powell and Elk Rivers in the Tennessee River 
system.
    Channel modification for commercial navigation has been shown to 
increase flood heights (Belt 1975, p. 684), partly as a result of an 
increase in stream bed slope (Hubbard et al. 1993, p. 137). Flood 
events are exacerbated, conveying large quantities of sediment, 
potentially with adsorbed contaminants, into streams. Channel 
maintenance often results in increased turbidity and sedimentation that 
often smothers mussels (Stansbery 1970, p. 10).
    Heavy metal-rich drainage from coal mining and associated 
sedimentation has adversely impacted historically diverse mussel faunas 
in the upper Cumberland and Tennessee River system streams. Strip 
mining continues to threaten mussel habitats in coal field drainages of 
the Cumberland Plateau, including streams harboring small fluted 
kidneyshell populations (e.g., Horse Lick Creek, Little South Fork, 
Powell River, Indian Creek). Portions of the upper Tennessee River 
system are also influenced by coal mining activities. In field studies, 
Powell River mussel populations were inversely correlated with coal 
fines in the substrate: Mussels were rare in areas with coal deposits 
(Kitchel et al. 1981, p. 21). In addition, decreased filtration times 
and increased movements were noted in laboratory-held mussels (Kitchel 
et al. 1981, p. 25). A quantitative study in the Powell River 
attributed a decline of federally listed mussels and the long-term 
decrease in overall species composition, since about 1980, to general 
stream degradation due primarily to coal mining activities in the 
headwaters (Ahlstedt and Tuberville 1997, pp. 74-76). Numerous gray-
water and black-water spill events have been documented in the Powell 
and Clinch River drainages over the past several years. The habitats of 
fluted kidneyshell, slabside pearlymussel, and other mussels in the 
Clinch and Powell Rivers are increasingly being threatened by coal 
mining activities. Price (2011, p. VIII-3) indicates total dissolved 
solids concentrations have continued to rise in the Powell and Clinch 
Rivers, with rapid increases in the upper Powell River, where coal 
mining is most prominent.
Oil and Natural Gas Development
    Oil and natural gas resources are present in some of the watersheds 
that are known or historically were known to support the fluted 
kidneyshell and slabside pearlymussel, including the Clinch, Powell, 
and Big South Fork Rivers. Exploration and extraction of these energy 
resources has the potential to result in increased siltation, a changed 
hydrograph (flow regime), and altered water quantity and quality even 
at a distance from the mine or well field. Although oil and natural gas 
extraction generally occurs away from the river, extensive road and 
pipeline networks are required to construct and maintain wells and 
transport the extracted resources. These road and pipeline networks 
frequently cross or occur near tributaries, contributing sediment to 
the receiving waterway. In addition, the construction and operation of 
wells may result in the illegal discharge of chemical contaminants and 
subsurface minerals.
Sedimentation
    Sedimentation is one of the most significant pollution problems for 
aquatic organisms (Waters 1995, pp. 2-3) and has been determined to be 
a major factor in mussel declines (Ellis 1936, pp. 39-40). Sources of 
silt and sediment include poorly designed and executed timber 
harvesting operations and associated activities; complete clearing of 
riparian vegetation for agricultural, silvicultural, or other purposes; 
and those construction, mining, and other practices that allow exposed 
earth to enter streams. Agricultural activities, specifically an 
increase in cattle grazing and the resultant nutrient enrichment and 
loss of riparian vegetation along the stream, are responsible for much 
of the sediment (Fraley and Ahlstedt 2000, p. 193; Hanlon et al. 2009, 
pp. 11-12).
    Heavy sediment loads can destroy mussel habitat, resulting in a 
corresponding shift in mussel fauna (Brim Box and Mossa 1999, p. 100). 
Excessive sedimentation can lead to rapid changes in stream channel 
position, channel shape, and bed elevation (Brim Box and Mossa 1999, p. 
102). Sedimentation has also been shown to impair the filter feeding 
ability of mussels, and high amounts of suspended sediments can dilute 
their food source (Dennis 1984, p. 212). We further describe the 
detrimental effects of sedimentation on these species under Factor E. 
Other Natural or Manmade Factors Affecting Its Continued Existence, 
below.
Chemical Contaminants
    Chemical contaminants are ubiquitous throughout the environment and 
are considered a major threat in the decline of mussel species (Richter 
et al. 1997, p. 1081; Strayer et al. 2004, p. 436;

[[Page 59280]]

Wang et al. 2007a, p. 2029; Cope et al. 2008, p. 451). Chemicals enter 
the environment through both point and nonpoint discharges, including 
spills, stormwater infrastructure, industrial sources, municipal 
effluents, and agricultural runoff. These sources contribute organic 
compounds, heavy metals, pesticides, and a wide variety of newly 
emerging contaminants to the aquatic environment. As a result, water 
and sediment quality can be degraded to the extent that mussel habitats 
and populations are adversely impacted. We further describe the 
detrimental effects of chemicals on these species under Factor E. Other 
Natural or Manmade Factors Affecting Its Continued Existence, below.
Other Stream Channel Alterations
    Other stream channel alterations that can impact mussel habitats 
include bridges, other road crossing structures, and activities that 
lower water tables (withdrawals). Levine et al. (2003, pp. 116-117) 
found that bridges built between 1950 and 1969 caused channel 
constriction and channel destabilization, resulting in mussel declines 
up to 300 meters (984 feet) downstream of road crossings. Culverts can 
act as barriers to fish passage (Wheeler et al. 2005, p. 149), 
particularly by increasing flow velocity (Warren and Pardew 1998, p. 
637). Stream channels become destabilized when improperly designed 
culverts or bridges change the morphology and interrupt the transport 
of woody debris, substrate, and water (Wheeler et al. 2005, p. 152). 
Water withdrawals for irrigation, municipal, and industrial water 
supplies are an increasing concern. For example, U.S. water consumption 
doubled from 1960 to 2000, and is likely to increase further (Naiman 
and Turner 2000, p. 960). Therefore, we anticipate road crossings, 
ground and surface water withdrawals, and potential stream dewatering 
to be threats to the habitat of the fluted kidneyshell and slabside 
pearlymussel.
Summary of Factor A
    Habitat loss and degradation negatively impact the fluted 
kidneyshell and slabside pearlymussel. Severe degradation from 
impoundments, gravel and coal mining, oil and natural gas development, 
sedimentation, chemical contaminants, and stream channel alterations 
threaten the stream habitat and water quality on which these species 
depend. Contaminants associated with coal mining (metals, other 
dissolved solids), municipal effluents (bacteria, nutrients, 
pharmaceuticals), and agriculture (fertilizers, pesticides, herbicides, 
and animal waste) cause degradation of water quality and habitats 
through increased acidity and conductivity, instream oxygen 
deficiencies, excess nutrification, and excessive algal growths. 
Furthermore, these threats faced by the fluted kidneyshell and slabside 
pearlymussel are imminent, and occur throughout the range of both 
species. Also, the threats are a result of ongoing projects expected to 
continue indefinitely, therefore perpetuating these impacts. As a 
result of the imminence of these threats, combined with the 
vulnerability of the remaining small, isolated populations to 
extirpation from natural and manmade threats, the present or threatened 
destruction, modification, or curtailment of the habitat and range of 
these species represents a threat to both the fluted kidneyshell and 
slabside pearlymussel now and into the future.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    The fluted kidneyshell and slabside pearlymussel are not 
commercially valuable species, but may be increasingly sought by 
collectors due to their increasing rarity. Although scientific 
collecting is not thought to represent a significant threat, localized 
populations could become impacted and possibly extirpated by 
overcollecting, particularly if regulations governing collection 
activity are not enforced. However, we do not consider overutilization 
for commercial, recreational, scientific, or educational purposes to be 
a threat to either species now or likely to become a threat in the 
future.

Factor C. Disease or Predation

    Little is known about diseases in mussels (Grizzle and Brunner 
2007, p. 6). Several mussel die-offs have been documented during the 
past 20 years across the United States (Neves 1987, pp. 8-11). Although 
the ultimate cause is unknown, some researchers believe that disease 
may be a factor. Warren and Haag (2005, p. 1394) hypothesized that 
declines in the Little South Fork Cumberland River, Kentucky, mussel 
fauna, including the once abundant fluted kidneyshell population, may 
have been at least partially attributed to disease, but no definitive 
cause has been determined. We have no specific documentation indicating 
that disease poses a threat to slabside pearlymussel populations.
    Juvenile and adult mussels are prey items for some invertebrate 
predators and parasites (e.g., nematodes and mites) and are prey for a 
few vertebrate species (e.g., raccoons, muskrats, otters, fish, and 
turtles) (Hart and Fuller 1974, pp. 225-240). Mussel parasites include 
water mites, trematodes, oligochaetes, leeches, copepods, bacteria, and 
protozoa (Grizzle and Brunner 2007, p. 6). Generally, parasites are not 
suspected of being a major limiting factor (Oesch 1984, p. 16); 
however, Gangloff et al. (2008, pp. 28-30) found that reproductive 
output and physiological condition were negatively correlated with mite 
and trematodes abundance, respectively. Stressors that reduce fitness 
may make mussels more susceptible to parasites (Butler 2007, p. 90).
    Neves and Odum (1989, entire) determined that muskrat predation on 
the fluted kidneyshell represents a localized threat by in the upper 
North Fork Holston River in Virginia. They concluded that muskrat 
predation could limit the recovery potential of endangered mussel 
species or contribute to the local extirpation of already depleted 
mussel populations. Although other mammals (e.g., raccoon, mink) 
occasionally feed on mussels, the threat from these predators is not 
considered to be significant. Predation does occur, but it is 
considered to be a normal aspect of the species' population dynamics 
and, therefore, not a threat to the slabside pearlymussel or fluted 
kidneyshell at the species' level under current conditions.
    In summary, there is little information on disease in mussels, and 
disease is not currently considered to be a threat to the fluted 
kidneyshell or slabside pearlymussel and is not likely to become so in 
the future. Although predation does occur and impacts local 
populations, we conclude that predation is not a threat to these 
species as a whole or likely to become so in the future.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

    The objective of the Federal Water Pollution Control Act, commonly 
referred to as the Clean Water Act (CWA) (33 U.S.C. 1251 et seq.), is 
to restore and maintain the chemical, physical, and biological 
integrity of the nation's waters by preventing point and nonpoint 
pollution sources. The CWA has a stated goal that ``. . . wherever 
attainable, an interim goal of water quality which provides for the 
protection and propagation of fish, shellfish, and wildlife and 
provides for recreation in and on the water be achieved by July 1, 
1983.'' States are responsible for setting and implementing water 
quality standards

[[Page 59281]]

that align with the requirements of the CWA.
    Nonpoint source (NPS) pollution comes from many diffuse sources, 
unlike pollution from industrial and sewage treatment plants. NPS 
pollution is caused by rainfall or snowmelt moving over and through the 
ground. As the runoff moves, it transports natural and human-made 
pollutants to lakes, rivers, wetlands, coastal waters, and ground 
waters. States report that NPS pollution is the leading remaining cause 
of water quality problems. The effects of NPS pollutants on specific 
waters vary and may not always be fully assessed. However, these 
pollutants have harmful effects on fisheries and wildlife (https://water.epa.gov/polwaste/nps/whatis.cfm).
    Sources of NPS pollution within the watersheds occupied by both 
mussels include agriculture, clearing of riparian vegetation, 
urbanization, road construction, and other practices that allow bare 
earth to enter streams. The Service has no information concerning the 
implementation of the CWA regarding NPS pollution specific to 
protection of both mussels. However, insufficient implementation of the 
CWA could become a threat to both mussel species if they continue to 
decline in numbers.
    The fluted kidneyshell and slabside pearlymussel continue to 
decline due to the effects of habitat destruction, poor water quality, 
contaminants, and other factors. However, there is no specific 
information known about the sensitivity of these mussels to common 
point source pollutants like industrial and municipal pollutants and 
very little information on other freshwater mussels. Because there is 
very little information known about water quality parameters necessary 
to fully protect freshwater mussels, such as the fluted kidneyshell and 
slabside pearlymussel, it is difficult to determine whether the CWA is 
adequately addressing the habitat and water quality threats to these 
species (see discussion under Factor A and Factor E). However, given 
that a goal of the CWA is to establish water quality standards that 
protect shellfish and given that documented declines of these mussel 
species still continue due to poor water quality and other factors, we 
take a conservative approach in favor of the species and conclude that 
the CWA has been insufficient to significantly reduce or remove these 
threats to the fluted kidneyshell and slabside pearlymussel.

Factor E. Other Natural or Manmade Factors Affecting Its Continued 
Existence

Altered Temperature Regimes
    Natural temperature regimes can be altered by impoundments, water 
releases from dams, industrial and municipal effluents, and changes in 
riparian habitat. Critical thermal limits for survival and normal 
functioning of many mussel species are unknown. High temperatures can 
reduce dissolved oxygen concentrations in the water, which slows 
growth, reduces glycogen stores, impairs respiration, and may inhibit 
reproduction (Hart and Fuller 1974, pp. 240-241). Low temperatures can 
significantly delay or prevent metamorphosis (Watters and O'Dee 1999, 
pp. 454-455). Water temperature increases have been documented to 
shorten the period of glochidial encystment, reduce the speed in which 
they turn upright, increase oxygen consumption, and slow burrowing and 
movement responses (Hart and Fuller 1974, pp. 240-241; Bartsch et al. 
2000, p. 237; Watters et al. 2001, p. 546; Schwalb and Pusch 2007, pp. 
264-265). Several studies have documented the influence of temperature 
on the timing of aspects of mussel reproduction (for example, Gray et 
al. 2002, p. 156; Allen et al. 2007, p. 85; Steingraeber et al. 2007, 
pp. 303-309). Peak glochidial releases are associated with water 
temperature thresholds that can be thermal minimums or thermal 
maximums, depending on the species (Watters and O'Dee 2000, p. 136). 
Abnormal temperature changes may cause particular problems for mussels 
whose reproductive cycles may be linked to fish reproductive cycles 
(Young and Williams 1984, entire).
Chemical Contaminants
    Chemical spills can be especially devastating to mussels because 
they may result in exposure of a relatively immobile species to 
extremely elevated contaminant concentrations that far exceed toxic 
levels and any water quality standards that might be in effect. Some 
notable spills that released large quantities of highly concentrated 
chemicals resulting in mortality to mussels and host fish include a 
kill on the Clinch River at Carbo, Virginia, from a power plant 
alkaline fly ash pond spill in 1967, and a sulfuric acid spill in 1970 
(Crossman et al. 1973, p. 6). In addition, approximately 18,000 mussels 
of several species, including the fluted kidneyshell and 750 
individuals from three endangered mussel species (tan riffleshell 
(Epioblasma florentina walkeri (=E. walkeri)), purple bean (Villosa 
perpurpurea), and rough rabbitsfoot (Quadrula cylindrica strigillata)), 
were eliminated from the upper Clinch River near Cedar Bluff, Virginia, 
in 1998, when an overturned tanker truck released approximately 6,100 
liters (1,600 gallons) of a chemical used in rubber manufacturing 
(Jones et al. 2001, p. 20; Schmerfeld 2006, p. 12). These are not the 
only instances where chemical spills have resulted in the loss of high 
numbers of mussels (Neves 1991, p. 252; Jones et al. 2001, p. 20; Brown 
et al. 2005, p. 1457; Schmerfeld 2006, pp. 12-13), but are provided as 
examples of the serious threat chemical spills pose to mussel species, 
such as the fluted kidneyshell and slabside pearlymussel.
    Cope et al. (2008, p. 451) evaluated the pathways of exposure to 
environmental pollutants for all four mollusk life stages (free 
glochidia, encysted glochidia, juveniles, and adults) and found that 
each life stage has both common and unique characteristics that 
contribute to observed differences in contaminant exposure and 
sensitivity. Very little is known about the potential mechanisms and 
consequences of waterborne toxicants on sperm viability. However, 
Watters (2011) demonstrated that the spermatozeugmata (sperm ball) 
produced and released by male mussels are sensitive to varying levels 
of salinity. When exposed to high enough salinity levels, the 
spermatozeugmata disassociate and can be rendered nonviable if they 
disassociate prior to entering a female mussel. This may pose yet 
another significant challenge for mussels to successfully fertilize 
eggs and promote recruitment if exposed to elevated salinity or 
conductivity levels in the ambient water column.
    In the female mollusk, the marsupial region of the gill is thought 
to be physiologically isolated from respiratory functions; this 
isolation may provide some level of protection from contaminant 
interference with a female's ability to achieve fertilization or brood 
glochidia (Cope et al. 2008, p. 454). However, a major exception to 
this hypothesis is with chemicals that act directly on the 
neuroendocrine pathways controlling reproduction (see discussion 
below). Nutritional and ionic exchange is possible between a brooding 
female and her glochidia, providing a route for chemicals (accumulated 
or waterborne) to disrupt biochemical and physiological pathways (such 
as maternal calcium transport for construction of the glochidial 
shell).
    Juvenile mussels typically remain burrowed beneath the sediment 
surface for 2 to 4 years. Residence beneath the

[[Page 59282]]

sediment surface necessitates deposit (pedal) feeding and a reliance on 
interstitial (pore) water for dissolved oxygen (Watters 2007, p. 56). 
The relative importance of juvenile fluted kidneyshell and slabside 
pearlymussel exposure to contaminants in overlying surface water, 
interstitial (pore) water, whole sediment, or food has not been 
adequately assessed. Exposure to contaminants from each of these routes 
varies with certain periods and environmental conditions (Cope et al. 
2008, pp. 453, 457).
    The primary routes of exposure to contaminants for adult fluted 
kidneyshell and slabside pearlymussel are surface water, sediment, 
interstitial (pore) water, and diet; adults can be exposed when either 
partially or completely burrowed in the substrate (Cope et al. 2008, p. 
453). Adult mussels have some ability to detect certain toxicants in 
the water and close their valves to avoid exposure (Van Hassel and 
Farris 2007, p. 6). Adult mussel toxicity and relative sensitivity 
(exposure and uptake of toxicants) may be reduced at high rather than 
at low toxicant concentrations because uptake is affected by the 
prolonged or periodic toxicant avoidance responses (when the avoidance 
behavior can no longer be sustained for physiological reasons) (Cope et 
al. 2008, p. 454). Toxicity results based on low-level exposure of 
adults are similar to estimates for glochidia and juveniles for some 
toxicants (e.g., copper). The duration of any toxicant avoidance 
response by an adult mussel is likely to be affected by several 
variables, such as species, age, shell thickness and gape, properties 
of the toxicant, and water temperature. There is a lack of information 
on toxicant response(s) specific to adult mussels (including the fluted 
kidneyshell and slabside pearlymussel), but results of tests using 
glochidia and juveniles may be valuable for protecting adults (Cope et 
al. 2008, p. 454).
    Chronic exposure to lower concentrations of contaminants, more 
likely to be found in aquatic environments, can also adversely affect 
mussels and result in the decline of mussel species. Such 
concentrations may not be immediately lethal, but over time, can result 
in mortality, reduced filtration efficiency, reduced growth, decreased 
reproduction, changes in enzyme activity, and behavioral changes to all 
mussel life stages. Frequently, procedures that evaluate the `safe' 
concentration of an environmental contaminant (e.g., national water 
quality criteria) do not have data for mussel species or exclude data 
that are available for mussels (March et al. 2007, pp. 2066-2067, 
2073).
    Current research is now focusing on the contaminant sensitivity of 
mussel glochidia and newly released juvenile mussels (Goudreau et al. 
1993, pp. 219-222; Jacobson et al. 1997, p. 2390; Valenti et al. 2005, 
pp. 1244-1245; Valenti et al. 2006, pp. 2514-2517; March et al. 2007, 
pp. 2068-2073; Wang et al. 2007b, pp. 2041-2046) and juveniles 
(Augspurger et al. 2003, p. 2569; Bartsch et al. 2003, p. 2561; Mummert 
et al. 2003, p. 2549; Valenti et al. 2005, pp. 1244-1245; Valenti et 
al. 2006, pp. 2514-2517; March et al. 2007, pp. 2068-2073; Wang et al. 
2007b, pp. 2041-2046; Wang et al. 2007c, pp. 2053-2055) to such 
contaminants as ammonia, metals, chlorine, and pesticides.
    One chemical that is particularly toxic to early life stages of 
mussels is ammonia. Sources of ammonia include agriculture (animal 
feedlots and nitrogenous fertilizers), municipal wastewater treatment 
plants, and industrial waste (Augspurger et al. 2007, p. 2026), as well 
as precipitation and natural processes (i.e., decomposition of organic 
nitrogen) (Goudreau et al. 1993, p. 212; Hickey and Martin 1999, p. 44; 
Augspurger et al. 2003, p. 2569; Newton 2003, p. 1243). Therefore, 
ammonia is considered a limiting factor for survival and recovery of 
some mussel species due to its ubiquity in aquatic environments and 
high level of toxicity, and because the highest concentrations 
typically occur within microhabitats inhabited by mussels (Augspurger 
et al. 2003, p. 2574). In addition, studies have shown that ammonia 
concentrations increase with increasing temperature and low flow 
conditions (Cherry et al. 2005, p. 378; Cooper et al. 2005, p. 381).
    Mussels are also affected by heavy metals (Keller and Zam 1991, p. 
543) such as cadmium, chromium, copper, mercury, and zinc, which can 
negatively affect biological processes such as growth, filtration 
efficiency, enzyme activity, valve closure, and behavior (Keller and 
Zam 1991, p. 543; Naimo 1995, pp. 351-355; Jacobson et al. 1997, p. 
2390; Valenti et al. 2005, p. 1244). Heavy metals occur in industrial 
and wastewater effluents and are often a result of atmospheric 
deposition from industrial processes and incinerators. Glochidia and 
juvenile mussels have recently been studied to determine the acute and 
chronic toxicity of copper to these life stages (Wang et al. 2007b, pp. 
2036-2047; Wang et al. 2007c, pp. 2048-2056). The chronic values 
determined for copper for survival and growth of juveniles are below 
the Environmental Protection Agency's (EPA's) 1996 chronic water 
quality criterion for copper (Wang et al. 2007c, pp. 2052-2055). March 
(2007, pp. 2066 and 2073) identified that copper water quality criteria 
and modified State water quality standards may not be protective of 
mussels.
    Mercury is another heavy metal that has the potential to negatively 
affect mussel populations, and it is receiving attention due to its 
widespread distribution and potential to adversely impact the 
environment. Mercury has been detected throughout aquatic environments 
as a product of municipal and industrial waste and atmospheric 
deposition from coal burning plants. Valenti et al. (2005, p. 1242) 
determined that for rainbow mussel, Villosa iris, glochidia were more 
sensitive to mercury than juvenile mussels, and that reduced growth in 
juveniles is seen when observed concentrations are higher than EPA's 
criteria for mercury. Based on these data, we believe that EPA's water 
quality standards for mercury should be protective of juvenile mussels 
and glochidia, except in cases of illegal dumping, permit violations, 
or spills. However, impacts to mussels from mercury toxicity may be 
occurring in some streams. According to the National Summary Data 
reported by States to the EPA, 4,716 monitored waters do not meet EPA 
standards for mercury in the United States (https://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T, accessed June 
28, 2012). Acute mercury toxicity was determined to be the cause of 
extirpation of a diverse mussel fauna for a 112-rkm (70-rmi) portion of 
the North Fork Holston River (Brown et al. 2005, pp. 1455-1457).
    In addition to ammonia, agricultural sources of chemical 
contaminants include two broad categories that have the potential to 
adversely impact mussel species: nutrients and pesticides. Nutrients 
(such as nitrogen and phosphorus) can impact streams when their 
concentrations reach levels that cannot be assimilated, a condition 
known as over-enrichment. Nutrient over-enrichment is primarily a 
result of runoff from livestock farms, feedlots, and heavily fertilized 
row crops (Peterjohn and Correll 1984, p. 1471). Over-enriched 
conditions are exacerbated by low-flow conditions, such as those 
experienced during typical summer-season flows. Bauer (1988, p. 244) 
found that excessive nitrogen concentrations can be detrimental to the 
adult pearl mussel (Margaritifera margaritifera), as was evident by the 
positive linear relationship between mortality and nitrate 
concentration. Also, a study of

[[Page 59283]]

mussel life span and size (Bauer 1992, p. 425) showed a negative 
correlation between growth rate and eutrophication, and longevity was 
reduced as the concentration of nitrates increased. Nutrient over-
enrichment can result in an increase in primary productivity, and the 
subsequent respiration depletes dissolved oxygen levels. This may be 
particularly detrimental to juvenile mussels, which inhabit the 
interstitial spaces in the substrate, where lower dissolved oxygen 
concentrations are more likely than on the sediment surface where 
adults tend to live (Sparks and Strayer 1998, pp. 132-133).
    Elevated concentrations of pesticide frequently occur in streams 
due to runoff, overspray application to row crops, and lack of adequate 
riparian buffers. The timing of agricultural pesticide applications and 
the reproductive and early life stages of mussels often coincide in the 
spring and summer, and thus impacts to mussels due to pesticides may be 
increased (Bringolf et al. 2007a, p. 2094). Little is known regarding 
the impact of currently used pesticides to mussels even though some 
pesticides, such as glyphosate (e.g., RoundupTM), are used 
globally. Recent studies tested the toxicity of glyphosate, its 
formulations, and a surfactant (MON 0818) used in several glyphosate 
formulations, to early life stages of the fatmucket (Lampsilis 
siliquoidea) (Bringolf et al. 2007a, p. 2094). Studies conducted with 
juvenile mussels and glochidia determined that the surfactant (MON 
0818) was the most toxic of the compounds tested and that fatmucket 
glochidia were the most sensitive of organisms tested to date (Bringolf 
et al. 2007a, p. 2094). RoundupTM, technical grade 
glyphosate isopropylamine salt, and isopropylamine were also acutely 
toxic to juveniles and glochidia (Bringolf et al. 2007a, p. 2097). The 
impacts of other pesticides including atrazine, chlorpyrifos, and 
permethrin on glochidia and juvenile life stages have also recently 
been studied (Bringolf et al. 2007b, p. 2101). One study determined 
that chlorpyrifos was toxic to both fatmucket glochidia and juveniles 
(Bringolf et al. 2007b, p. 2104). The above results indicate the 
potential toxicity of commonly applied pesticides and the threat to 
mussel species as a result of the widespread use of these pesticides. 
All of these pesticides are commonly used throughout the range of the 
fluted kidneyshell and slabside pearlymussel.
    Pharmaceutical chemicals used in commonly consumed drugs are 
increasingly found in surface waters downstream from municipal 
effluents. A nationwide study sampling 139 stream sites in 30 States 
detected the presence of numerous pharmaceuticals, hormones, and other 
organic wastewater contaminants downstream from urban development and 
livestock production areas (Kolpin et al. 2002, pp. 1208-1210). 
Exposure to waterborne and, potentially to sediment, toxicant chemicals 
that act directly on the neuroendocrine pathways controlling 
reproduction can cause premature release of viable or nonviable 
glochidia. For example, the active ingredient in many human 
prescription anti-depressant drugs belonging to the class of selective 
serotonin reuptake inhibitors may exert negative reproductive effects 
on mussels because of their action on serotonin and other 
neuroendocrine pathways (Cope et al. 2008, pp. 455). These waterborne 
chemicals alter mussel behavior and influence successful attachment of 
glochidia on fish hosts, and therefore, may have population-level 
implications for the fluted kidneyshell and slabside pearlymussel. This 
information indicates it is likely that chemical contaminants have 
contributed to declining fluted kidneyshell and slabside pearlymussel 
populations and will likely continue to be a threat to these species in 
the future. These threats result from spills that are immediately 
lethal to these species, as well as chronic contaminant exposure, which 
results in death, reduced growth, or reduced reproduction of fluted 
kidneyshell and slabside pearlymussel.
Sedimentation
    Impacts resulting from sediments have been noted for many 
components of aquatic communities. For example, sediments have been 
shown to abrade or suffocate periphyton (organisms attached to 
underwater surfaces); affect respiration, growth, reproductive success, 
and behavior of aquatic insects and mussels; and affect fish growth, 
survival, and reproduction (Waters 1995, pp. 173-175).
    Increased turbidity from suspended sediment can reduce or eliminate 
juvenile mussel recruitment (Negus 1966, p. 525; Box and Mossa 1999, 
pp. 101-102). Many mussel species use visual cues to attract host 
fishes; such a reproductive strategy depends on clear water for 
success. For example, increased turbidity may impact the life cycle of 
the southern sandshell, Hamiota australis, by reducing the chance that 
a sight-feeding host fish will encounter the visual display of the 
mussel's superconglutinate lure (Haag et al. 1995, p. 475; Blalock-
Herod et al. 2002, p. 1885). If the superconglutinate is not 
encountered by a host within a short time period, the glochidia will 
become nonviable (O'Brien and Brim Box 1999, p. 133). Also, evidence 
suggests that conglutinates of the southern kidneyshell (another 
species of Ptychobranchus, P. jonesi), once released from the female 
mussel in an attempt to lure potential host fish, must adhere to hard 
surfaces in order to be seen by its fish host. If the surface becomes 
covered in fine sediments, the conglutinate cannot attach and is swept 
away (Hartfield and Hartfield 1996, p. 373).
Population Fragmentation and Isolation
    Population isolation prohibits the natural interchange of genetic 
material between populations, and small population size reduces the 
reservoir of genetic diversity within populations, which can lead to 
inbreeding depression (Allendorf and Luikart 2007, pp. 117-146). Small, 
isolated populations, therefore, are more susceptible to environmental 
pressures, including habitat degradation and stochastic events, and 
thus are the most susceptible to extinction (Primack 2008, pp. 151-
153). It is likely that some populations of the fluted kidneyshell and 
slabside pearlymussel are below the effective population size 
(Soul[eacute] 1980, pp. 162-164; Allendorf and Luikart 2007, pp. 147-
170) required to maintain long-term genetic and population viability.
    The present distribution and status of the fluted kidneyshell in 
the upper Cumberland River system in Kentucky may provide an excellent 
example of the detrimental bottleneck effect resulting when a minimum 
viable population size is not maintained. A once large population of 
this species occurred throughout the upper Cumberland River mainstem 
below Cumberland Falls and in several larger tributary systems. In this 
region, there were no absolute barriers to genetic interchange among 
its subpopulations (and those of its host fishes) that occurred in 
various streams. With the completion of Wolf Creek Dam in the late 
1960s, the mainstem population was soon extirpated, and the remaining 
populations isolated by the filling of Cumberland Reservoir. Whereas 
small, isolated, tributary populations of imperiled, short-lived 
species (e.g., most fishes) would have died out within a decade or so 
after impoundment, the long-lived fluted kidneyshell would potentially 
take decades to expire post-impoundment. Without the level of genetic 
interchange the species experienced historically (i.e., without the 
reservoir barrier), isolated populations may be slowly

[[Page 59284]]

dying out. The fluted kidneyshell and slabside pearlymussel were 
similarly isolated by the completion of multiple reservoirs in the 
Tennessee River system. Even given the improbable absence of 
anthropogenic impacts, we may lose smaller isolated populations of the 
fluted kidneyshell and slabside pearlymussel to the devastating 
consequences of below-threshold effective population size (the minimum 
population size that is needed for the population to reproduce and 
continue to be viable).
Random Catastrophic Events
    The remaining populations of the fluted kidneyshell and slabside 
pearlymussel are generally small and geographically isolated. The 
patchy distribution pattern of populations in short river reaches makes 
them much more susceptible to extirpation from single catastrophic 
events, such as toxic chemical spills. Such a spill occurred in the 
upper Clinch River in 1998, killing many fluted kidneyshell and 
thousands of specimens of other mussel species, including three 
federally listed species (Henley et al. 2002, entire; see Chemical 
Contaminants section above). High levels of isolation make natural 
recolonization of any extirpated population unlikely.
Climate Change
    Our analyses under the Act include consideration of ongoing and 
projected changes in climate. The terms ``climate'' and ``climate 
change'' are defined by the Intergovernmental Panel on Climate Change 
(IPCC). ``Climate'' refers to the mean (average) and variability of 
different types of weather conditions over time, with 30 years being a 
typical period for such measurements, although shorter or longer 
periods also may be used (IPCC 2007, p. 78). The term ``climate 
change'' thus refers to a change in the mean or variability of one or 
more measures of climate (e.g., temperature or precipitation) that 
persists for an extended period, typically decades or longer, whether 
the change is due to natural variability, human activity, or both (IPCC 
2007, p. 78). Various types of changes in climate can have direct or 
indirect effects on species. These effects may be positive, neutral, or 
negative and they may change over time, depending on the species and 
other relevant considerations, such as the effects of interactions of 
climate with other variables (e.g., habitat fragmentation) (IPCC 2007, 
pp. 8-14, 18-19). In our analyses, we use our expert judgment to weigh 
relevant information, including uncertainty, in our consideration of 
various aspects of climate change.
    There is a growing concern that climate change may lead to 
increased frequency of severe storms and droughts (McLaughlin et al. 
2002, p. 6074; Cook et al. 2004, p. 1015; Golladay et al. 2004, p. 
504). Specific effects of climate change to mussels, their habitats, 
and their fish hosts could include changes in stream temperature 
regimes and changes in the timing and levels of precipitation, causing 
more frequent and severe floods and droughts. Increases in temperature 
and reductions in flow can also lower dissolved oxygen levels in 
interstitial habitats, which can be lethal to juveniles (Sparks and 
Strayer 1998, pp. 131-133). Even small increases in temperature can 
cause reductions in the survival of freshwater mussel glochidia and 
juveniles, and temperatures currently encountered in the temperate 
United States during summers are close to or above the upper thermal 
tolerances of early life stages of freshwater mussels (Pandolfo et al. 
2010, pp. 965, 967). Effects to mussel populations from these 
environmental changes could include reduced abundance and biomass, 
altered species composition, and reduced host fish availability 
(Galbraith et al. 2010, pp. 1180-1182). The present conservation 
status, complex life histories, and specific habitat requirements of 
mussels suggest that they may be quite sensitive to the effects of 
climate change (Hastie et al. 2003, p. 45).
    During high flows, flood scour can dislodge mussels potentially 
causing them to be injured, buried, swept into unsuitable habitats, or 
stranded and perish when flood waters recede (Vannote and Minshall 
1982, p. 4105; Tucker 1996, p. 435; Hastie et al. 2001, pp. 107-115; 
Peterson et al. 2011, unpaginated). Increased human demand and 
competition for surface and ground water resources for irrigation and 
consumption during drought can cause drastic reductions in stream flows 
and alterations to hydrology (Golladay et al. 2004, p. 504; Golladay et 
al. 2007, unpaginated). Extended droughts occurred in the Southeast 
during 1998 to 2002, and again in 2006 to 2008. The effects of these 
recent droughts on these mussels are unknown; however, substantial 
declines in mussel diversity and abundance as a direct result of 
drought have been documented in other southeastern streams (Golladay et 
al. 2004, pp. 494-503; Haag and Warren 2008, p. 1165).
Nonindigenous Species
    The Asian clam (Corbicula fluminea) has been introduced to the 
Cumberland and Tennessee River drainages and may be adversely affecting 
the fluted kidneyshell and slabside pearlymussel, particularly 
juveniles, through direct competition for space and resources (Neves 
and Widlak 1987, p. 6). Dense populations of Asian clams may ingest 
large numbers of unionid sperm, glochidia, and newly metamorphosed 
juveniles, and may actively disturb sediments, reducing habitable space 
for juvenile native mussels or displacing them downstream (Strayer 
1999, p. 82; Yeager et al. 2000, pp. 255-256).
    Asian clam densities vary widely in the absence of native mussels 
or in patches with sparse mussel concentrations, but Asian clam density 
is rarely observed to be high in dense mussel beds, indicating that the 
clam is unable to successfully invade small-scale habitat patches with 
high unionid biomass (Vaughn and Spooner 2006, pp. 334-335). The 
invading clam, therefore, appears to preferentially invade sites where 
mussels are already in decline (Strayer 1999, pp. 82-83; Vaughn and 
Spooner 2006, pp. 332-336) and does not appear to be a causative factor 
in the decline of mussels in dense beds. However, an Asian clam 
population that thrives in previously stressed, sparse mussel 
populations might exacerbate unionid imperilment through competition 
and impeding mussel population expansion (Vaughn and Spooner 2006, pp. 
335-336).
Summary of Factor E
    Other natural and manmade factors, such as alteration of natural 
temperature regimes below dams; chemical contaminants; sedimentation; 
small, isolated populations; and low genetic diversity, combined with 
localized extinctions from point source pollution or accidental toxic 
chemical spills, habitat modification and progressive degradation by 
nonpoint source pollutants, natural catastrophic changes to habitat 
through flood scour or drought as exacerbated by climate change, and 
nonindigenous species are threats to remaining populations of the 
fluted kidneyshell and slabside pearlymussel across their respective 
ranges now and into the future.

Determination

    We have carefully assessed the best scientific and commercial data 
available regarding the past, present, and future threats to the fluted 
kidneyshell and slabside pearlymussel. The Act defines an endangered 
species as ``any species which is in danger of extinction throughout 
all or a significant portion of its range,'' and a threatened species 
as ``any species which is likely to become an endangered species within 
the foreseeable future throughout all or a

[[Page 59285]]

significant portion of its range.'' As described in detail above, these 
two species occupy only portions of their historical ranges, are 
limited to fewer than 20 viable populations, and are currently at risk 
throughout all of their respective ranges due to ongoing threats of 
habitat destruction and modification (Factor A) and other natural or 
manmade factors affecting their continued existence (Factor E). 
Specifically, primary sources of stress and threats include 
impoundments, mining, oil and gas exploration, sedimentation, chemical 
contaminants, temperature regime alterations, recurring drought and 
flooding, population fragmentation and isolation, loss of fish hosts, 
and the introduced Asian clam. The data show that existing regulatory 
mechanisms, such as the CWA, are inadequate to reduce these threats 
(Factor D). These threats are currently impacting these species 
throughout their ranges and are projected to continue and potentially 
worsen in the future.
    Species with small ranges, few populations, and small or declining 
population sizes are the most vulnerable to extinction (Primack 2008, 
p. 137). The effects of certain factors, particularly habitat 
degradation and loss, catastrophic events, and introduced species, 
increase in magnitude when population size is small (Soul[eacute] 1987, 
pp. 33, 71; Primack 2008, pp. 133-135, 152). When combining the effects 
of historical, current, and future habitat loss and degradation; 
historical and future drought; and the exacerbating effects of small 
and declining population sizes and curtailed ranges, the fluted 
kidneyshell and slabside pearlymussel are in danger of extinction 
throughout all of their ranges. In addition, any factor (i.e., habitat 
loss or other natural and manmade factors) that results in a further 
decline in habitat or individuals may be problematic for the long-term 
recovery of these species. Therefore, based on the best available 
scientific and commercial data, we list the fluted kidneyshell and 
slabside pearlymussel as endangered species in accordance with sections 
3(6) and 4(a)(1) of the Act.
    Resource managers have been making attempts to reintroduce the 
fluted kidneyshell into historical habitat over the past decade. These 
mussels have been translocated from the Clinch River into the upper 
Duck River, Nolichucky River, Big South Fork of the Cumberland River, 
Little Tennessee River bypass below Calderwood Dam, Indian Creek and 
North Fork Holston River. Despite all of these reintroduction attempts 
only three sites are showing signs of any success. The only population 
of the fluted kidneyshell known to be large, stable, and viable is in 
the Clinch River, but it is in a relatively short reach of river 
primarily in the vicinity of the Tennessee-Virginia State line. Based 
on recent information, the overall population status of the fluted 
kidneyshell is declining rangewide. We find that a threatened species 
status is not appropriate for the fluted kidneyshell because of its 
contracted range, because the threats are occurring rangewide and are 
not localized, because the threats are ongoing and expected to continue 
into the future, and because the reintroduction attempts have been 
unable to stop or reduce the overall population decline.
    There have been no reintroductions for the slabside pearly mussel. 
The slabside pearlymussel has been extirpated from more than 50 percent 
of the streams from which the species was historically known to occur 
and occurs in only 13 extant populations. The overall population of the 
slabside pearlymussel appears to be declining rangewide, with 
relatively good numbers and apparent viability in just two streams 
(Duck and Paint Rock Rivers). Most of the other populations are of 
questionable viability and may be on the verge of extirpation (e.g., 
Powell and Hiwassee Rivers; Big Moccasin Creek). Therefore, we find 
that a threatened species status is not appropriate for the slabside 
pearlymussel because of its contracted range, because the threats are 
occurring rangewide and are not localized, because the threats are 
ongoing and expected to continue into the future, and because the 
species is declining rangewide and many populations are on the verge of 
extirpation.
    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. The threats to the survival of these 
species occur throughout the species' ranges and are not restricted to 
any particular significant portion of their ranges. Accordingly, our 
assessment and determination applies to these species throughout their 
entire ranges.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation by Federal, State, and local agencies; private 
organizations; and individuals. The Act encourages cooperation with the 
States and requires that recovery actions be carried out for all listed 
species. The protection measures required of Federal agencies and the 
prohibitions against certain activities involving listed wildlife are 
discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Subsection 4(f) of the Act requires the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed, preparation of a draft and final 
recovery plan, and revisions to the plan as significant new information 
becomes available. The recovery outline guides the immediate 
implementation of urgent recovery actions and describes the process to 
be used to develop a recovery plan. The recovery plan identifies site-
specific management actions that will achieve recovery of the species, 
measurable criteria that determine when a species may be downlisted or 
delisted, and methods for monitoring recovery progress. Recovery plans 
also establish a framework for agencies to coordinate their recovery 
efforts and provide estimates of the cost of implementing recovery 
tasks. Recovery teams (comprised of species experts, Federal and State 
agencies, nongovernment organizations, and stakeholders) are often 
established to develop recovery plans. When completed, the draft and 
final recovery plans will be available on our Web site (https://www.fws.gov/endangered) and from our Tennessee Ecological Services 
Field Office (see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include

[[Page 59286]]

habitat restoration (e.g., restoration of native vegetation), research, 
captive propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    When this rule is effective (see DATES), funding for recovery 
actions will be available from a variety of sources, including Federal 
budgets, State programs, and cost share grants for non-Federal 
landowners, the academic community, and nongovernmental organizations. 
In addition, under section 6 of the Act, the States of Alabama, 
Kentucky, Mississippi, Tennessee and Virginia will be eligible for 
Federal funds to implement management actions that promote the 
protection and recovery of these two species. Information on our grant 
programs that are available to aid species recovery can be found at: 
https://www.fws.gov/grants.
    Please let us know if you are interested in participating in 
recovery efforts for the fluted kidneyshell and slabside pearlymussel. 
Additionally, we invite you to submit any new information on these 
species whenever it becomes available and any information you may have 
for recovery planning purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as 
endangered or threatened and with respect to its critical habitat, if 
any is designated. Regulations implementing this interagency 
cooperation provision of the Act are codified at 50 CFR part 402. 
Section 7(a)(4) of the Act requires Federal agencies to confer with the 
Service on any action that is likely to jeopardize the continued 
existence of a species proposed for listing or result in destruction or 
adverse modification of proposed critical habitat. If a species is 
listed subsequently, section 7(a)(2) of the Act requires Federal 
agencies to ensure that activities they authorize, fund, or carry out 
are not likely to jeopardize the continued existence of the species or 
destroy or adversely modify its critical habitat. If a Federal action 
may affect a listed species or its critical habitat, the responsible 
Federal agency must enter into formal consultation with the Service.
    Federal agency actions within the species habitat that may require 
conference or consultation or both as described in the preceding 
paragraph include management of and any other landscape altering 
activities on Federal lands administered by the U.S. Forest Service; 
issuance of section 404 CWA permits by the U.S. Army Corps of 
Engineers; licensing of hydroelectric dams, and construction and 
management of gas pipeline and power line rights-of-way approved by the 
Federal Energy Regulatory Commission; issuance of 26a permits by the 
Tennessee Valley Authority; construction and maintenance of roads or 
highways funded by the Federal Highway Administration; and land 
management practices administered by the U.S. Department of 
Agriculture. It has been the experience of the Service from 
consultations on other species, however, that nearly all section 7 
consultations have been resolved so that the species have been 
protected and the project objectives have been met.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all endangered and 
threatened wildlife. The prohibitions of section 9(a)(2), codified at 
50 CFR 17.21 for endangered wildlife, make it illegal for any person 
subject to the jurisdiction of the United States to take (includes 
harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or 
collect; or to attempt any of these), import, export, ship in 
interstate commerce in the course of commercial activity, or sell or 
offer for sale in interstate or foreign commerce any listed species. 
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also 
illegal to possess, sell, deliver, carry, transport, or ship any such 
wildlife that has been taken illegally. Certain exceptions apply to 
agents of the Service and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered and threatened wildlife species under certain 
circumstances. Regulations governing permits are codified at 50 CFR 
17.22 for endangered species, and at 17.32 for threatened species. With 
regard to endangered wildlife, a permit must be issued for the 
following purposes: for scientific purposes, to enhance the propagation 
or survival of the species, and for incidental take in connection with 
otherwise lawful activities.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify, to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a listing on 
proposed and ongoing activities within the range of listed species. The 
following activities could potentially result in a violation of section 
9 of the Act; this list is not comprehensive:
    (1) Unauthorized collecting, handling, possessing, selling, 
delivering, carrying, or transporting of the species, including import 
or export across State lines and international boundaries, except for 
properly documented antique specimens of these taxa at least 100 years 
old, as defined by section 10(h)(1) of the Act.
    (2) Introduction of nonnative species, such as the Asian clam, that 
compete with or prey upon these mussel species.
    (3) Unauthorized modification of the channel, substrate, 
temperature, or water flow of any stream or water body in which these 
species are known to occur.
    (4) Unauthorized discharge of chemicals or fill material into any 
waters in which the fluted kidneyshell and slabside pearlymussel are 
known to occur.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Tennessee 
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT). 
Requests for copies of the regulations concerning listed animals and 
general inquiries regarding prohibitions and permits may be addressed 
to the U.S. Fish and Wildlife Service, Endangered Species Permits, 1875 
Century Boulevard, Suite 200, Atlanta, GA 30345; telephone: 404-679-
7140; facsimile: 404-679-7081.

Required Determinations

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with listing a species as endangered or 
threatened under the Endangered Species Act. We published a notice 
outlining our reasons for this determination in the Federal Register on 
October 25, 1983 (48 FR 49244).

References Cited

    A complete list of all references cited in this final rule is 
available on the Internet at https://www.regulations.gov, or upon 
request from the Tennessee Ecological Services Field Office (see FOR 
FURTHER INFORMATION CONTACT).

[[Page 59287]]

Authors

    The primary authors of this final rule are the staff members of the 
Tennessee Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as follows:

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; 4201-4245, unless 
otherwise noted.


0
2. Amend Sec.  17.11(h) by adding entries for ``Kidneyshell, fluted'' 
and ``Pearlymussel, slabside'' to the List of Endangered and Threatened 
Wildlife in alphabetical order under ``CLAMS'':


Sec.  17.11  Endangered and threatened wildlife.

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    (h) * * *

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                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
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                                                                      * * * * * * *
              Clams
 
                                                                      * * * * * * *
Kidneyshell, fluted..............  Ptychobranchus        U.S.A. (AL, KY, TN,  Entire.............  E                       825     17.95(f)           NA
                                    subtentum.            VA).
 
                                                                      * * * * * * *
Pearlymussel, slabside...........  Pleuronaia            U.S.A. (AL, KY, MS,  Entire.............  E                       825     17.95(f)           NA
                                    dolabelloides.        TN, VA).
 
                                                                      * * * * * * *
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    Dated: September 17, 2013.
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2013-23356 Filed 9-25-13; 8:45 am]
BILLING CODE 4310-55-P