[Federal Register Volume 77, Number 49 (Tuesday, March 13, 2012)]
[Rules and Regulations]
[Pages 14913-14949]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-5603]



[[Page 14913]]

Vol. 77

Tuesday,

No. 49

March 13, 2012

Part III





Department of the Interior





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 Fish and Wildlife Service





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50 CFR Part 17





 Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Sheepnose and Spectaclecase Mussels 
Throughout Their Range; Final Rule

Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Rules 
and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R3-ES-2010-0050; 4500030113]
RIN 1018-AV93


Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Sheepnose and Spectaclecase Mussels 
Throughout Their Range

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 status under the Endangered Species Act of 1973 (Act), as 
amended, for the spectaclecase (Cumberlandia monodonta) and sheepnose 
(Plethobasus cyphyus), two freshwater mussels. This final rule 
implements the Federal protections provided by the Act for these 
species throughout their ranges, including sheepnose in Alabama, 
Illinois, Indiana, Iowa, Kentucky, Minnesota, Mississippi, Missouri, 
Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin, 
and spectaclecase in Alabama, Arkansas, Illinois, Indiana, Iowa, 
Kansas, Kentucky, Minnesota, Missouri, Ohio, Tennessee, Virginia, West 
Virginia, and Wisconsin. We determined that critical habitat for the 
spectaclecase and sheepnose is prudent, but not determinable at this 
time.

DATES: This rule becomes effective on April 12, 2012.

ADDRESSES: This final rule is available on the Internet at http://www.regulations.gov at Docket No. FWS-R3-ES-2010-0050. Comments and 
materials received, as well as supporting documentation used in 
preparing this final rule will be available for public inspection, by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Rock Island, Illinois Ecological Services Field 
Office, 1511 47th Avenue, Moline, IL 61265; telephone 309-757-5800.

FOR FURTHER INFORMATION CONTACT: Richard Nelson, Field Supervisor, at 
the U.S. Fish and Wildlife Service, Rock Island, Illinois Ecological 
Services Field Office, (see ADDRESSES section). If you use a 
telecommunications device for the deaf (TDD), call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

Previous Federal Action

    Federal actions for these species prior to January 19, 2011, are 
outlined in our proposed rule for these actions (76 FR 3392-3420). 
Publication of the proposed rule opened a 60-day comment period, which 
closed on March 21, 2011.

Species Descriptions

    The spectaclecase (Cumberlandia monodonta) is a member of the 
mussel family Margaritiferidae and was originally described as Unio 
monodonta Say, 1829. The type locality is the Falls of the Ohio (on the 
Ohio River in the vicinity of Louisville, Kentucky, and adjacent 
Indiana), and the Wabash River (probably the lower portion in Illinois 
and Indiana) (Parmalee and Bogan 1998, p. 49). Parmalee and Bogan 
(1998, p. 49) summarized the synonymy of the spectaclecase. The species 
has been placed in the genera Unio, Margaritana, Alasmidonta, 
Margarita, Margaron, and Margaritifera at various times in history. 
Ortmann (1912, p. 13) placed it in the monotypic (a taxonomic group 
with only one biological type) genus Cumberlandia in the family 
Margaritiferidae. Currently recognized synonymy includes Unio 
soleniformis (Lea). Smith (2001, p. 43) reassigned the spectaclecase to 
the Holarctic genus Margaritinopsis based on shell and gill characters. 
The Service, however, will defer to the Committee on Scientific and 
Vernacular Names of Mollusks of the Council of Systematic 
Malacologists, American Malacological Union (Turgeon et al. 1998), on 
whether the genus Margaritinopsis is accepted as valid for the 
spectaclecase. Until an official decision is made, the Service will use 
the commonly accepted Cumberlandia for the genus of this species. 
Spectaclecase is the accepted common name for Cumberlandia monodonta 
(Turgeon et al. 1998, p. 32).
    The spectaclecase is a large mussel that reaches at least 9.25 
inches (23.5 centimeters (cm)) in length (Havlik 1994, p. 19). The 
shape of the shell is greatly elongated, sometimes arcuate (curved), 
and moderately inflated, with the valves being solid and moderately 
thick, especially in older individuals (Parmalee and Bogan 1998, p. 
49). Both anterior and posterior ends of the shell are rounded with a 
shallow depression near the center of the shell (Baird 2000, p. 6; 
Parmalee and Bogan 1998, p. 49). The anterior end is higher than the 
posterior end (Baird 2000, p. 6). The posterior ridge is low and 
broadly rounded (Parmalee and Bogan 1998, p. 50). Year-one specimens 
have heavy ridges running parallel with the growth arrests, which are 
shell lines that indicate slower periods of growth, thought to be laid 
down annually (Baird 2000, p. 6). The periostracum (external shell 
surface) is somewhat smooth, rayless, and light yellow, greenish-tan, 
or brown in young specimens, becoming rough and dark brown to black in 
old shells (Parmalee and Bogan 1998, p. 50). The shell commonly will 
crack posteriorly when dried (Oesch 1984, p. 31).
    Internally, the single pseudocardinal tooth (a triangular tooth-
like structure along the hinge line of the internal portion of the 
shell) is simple and peg-like in the right valve, fitting into a 
depression in the left (Parmalee and Bogan 1998, p. 50). The lateral 
teeth are straight and single in the right valve, and double in the 
left valve, but become fused with age into an indistinct raised hinge 
line (Parmalee and Bogan 1998, p. 50). The soft anatomy was described 
by Williams et al. (2008, pp. 497-498). The color of the nacre 
(interior covering of the shell) is white, occasionally granular and 
pitted, mostly iridescent in young specimens, but becoming iridescent 
posteriorly in older shells (Parmalee and Bogan 1998, p. 50). There are 
no differences between the sexes in the shells of this species (Baird 
2000, p. 19). Key characters for distinguishing the spectaclecase from 
other mussels are its large size, elongate shape, arcuate ventral 
margin, dark coloration, roughened periostracum, poorly developed 
teeth, and white nacre (Oesch 1984, pp. 31-32). No other North American 
mussel species has this suite of characters.
    The sheepnose (Plethobasus cyphyus) is a member of the mussel 
family Unionidae and was originally described as Obliquaria cyphya 
Rafinesque, 1820. The type locality is the Falls of the Ohio (Parmalee 
and Bogan 1998, p. 175) on the Ohio River in the vicinity of 
Louisville, Kentucky, and adjacent Indiana. Parmalee and Bogan (1998, 
p. 175) summarized the synonymy of the species. Over the years, the 
name of this species has been variably spelled cyphya, scyphius, 
cyphius, cyphia, cyphyum, and ultimately cyphyus. Over the years the 
species has been placed in the genera Obliquaria, Unio, Pleurobema, 
Margarita, and Margaron. It was ultimately placed in the genus 
Plethobasus by Ortmann (1919, pp. 65-66), where it remains today 
(Turgeon et al. 1998, p. 35). The Service recognizes Unio aesopus and 
U. compertus as synonyms of Plethobasus cyphyus. Sheepnose is the 
accepted common name for Plethobasus cyphyus as established by the 
Committee on Scientific and Vernacular Names of

[[Page 14915]]

Mollusks of the Council of Systematic Malacologists, American 
Malacological Union (Turgeon et al. 1998, p. 35). The Service also 
recognizes ``bullhead'' and ``clear profit'' as older common names for 
the sheepnose.
    Key characters useful for distinguishing the sheepnose from other 
mussels are its color, the occurrence of central tubercles, and its 
general shape. Oesch (1984, p. 120) and Parmalee and Bogan (1998, p. 
176) describe the sheepnose as a medium-sized mussel that reaches 
nearly 5 inches (13 cm) in length. The shell is elongate ovate in 
shape, moderately inflated, and with thick, solid valves. The anterior 
end of the shell is rounded, but the posterior end is somewhat bluntly 
pointed to truncate. The dorsal margin of the shell is nearly straight, 
while the ventral margin is uniformly rounded or slightly convex. The 
posterior ridge is gently rounded, becoming flattened ventrally and 
somewhat biangular. There is a row of large, broad tubercular swellings 
on the center of the shell extending from the beak to the ventral 
margin. A broad, shallow sulcus (depression on the furrow on the 
outside surface of the shell) lies between the posterior ridge and 
central row. Beaks are elevated, high, and placed near the anterior 
margin. Juvenile beak sculpture consists of a few concentric ridges at 
the tip of the beaks. The periostracum is generally smooth, shiny, 
rayless, and light yellow to a dull yellowish brown. Concentric ridges 
resulting from growth arrests are usually darker.
    Oesch (1984, p. 120) describes the internal anatomy of the 
sheepnose as the left valve having two heavy, erect, roughened, 
somewhat triangular, and divergent pseudocardinal teeth. The right 
valve has a large, triangular, roughened pseudocardinal tooth. The 
lateral teeth are heavy, long, slightly curved, and serrated. The beak 
cavity is shallow to moderately deep. The soft anatomy was described by 
Williams et al. (2008, p. 94). The color of the nacre is generally 
white, but may be pinkish to cream-colored and iridescent posteriorly. 
There are no differences between the sexes in the shells of this 
species. The shell of the sheepnose is extremely hard and was given the 
name ``clear profit'' by early commercial shellers, being too hard to 
cut into buttons (Wilson and Clark 1914, p. 57). The species also 
preserves well in archaeological material (Morrison 1942, p. 357).

Life History

    The general biology of the spectaclecase and sheepnose are similar 
to other bivalve mollusks belonging to the families Margaritiferidae 
and Unionidae, order Unioniformes or Unionoida. Adult mussels 
suspension-feed, spending their entire lives partially or completely 
buried within the substrate (Murray and Leonard 1962, p. 27). Adults 
feed on algae, bacteria, detritus, microscopic animals, and dissolved 
organic material (Christian et al. 2004, pp. 108-109; Nichols and 
Garling 2000, p. 873; Silverman et al. 1997, p. 1859; Strayer et al. 
2004, pp. 430-431). Recent evidence suggests that adult mussels may 
also deposit feed on particles in the sediment (Raikow and Hamilton 
2001, p. 520). For their first several months, juvenile mussels employ 
foot (pedal) feeding, consuming bacteria, algae, and detritus (Yeager 
et al. 1994, p. 221).
    As a group, mussel longevity varies tremendously with some species 
living only about 4 years (Haag and Rypel 2010, p. 5) but possibly up 
to 100 to 200 years in other species (Ziuganov et al. 2000, p. 102). 
However, the vast majority of species live a few decades (Haag and 
Rypel 2010, pp. 4-6). Baird (2000, pp. 54, 59, 67) aged 278 specimens 
of the spectaclecase in Missouri by sectioning the hinge ligament, as 
most margaritiferids are aged. The maximum age determined was 56 years, 
but he surmised that some large individuals may have been older. A very 
large specimen (9.25 inches (23.5 cm)) from the St. Croix River, 
Minnesota and Wisconsin, was estimated (based on external growth ring 
counts) to be approximately 70 years old (Havlik 1994, p. 19). 
Sheepnose longevity has been reported as being nearly 30 years (Watters 
et al. 2009, p. 221). Thick shelled mussels from large rivers, like 
sheepnose, are thought to live longer than other species (Stansbery 
1961, p. 16).
    Mussels tend to grow relatively rapidly for the first few years, 
and then slow appreciably at sexual maturity, when energy presumably is 
being diverted from growth to reproductive activities (Baird 2000, pp. 
66-67). In spectaclecase, the biggest change in growth rate appears to 
occur at 10 to 15 years of age, which suggests that significant 
reproductive investment does not occur until they reach 10 years of age 
(Baird 2000, pp. 66-67).
    Margaritiferids and unionids have an unusual mode of reproduction. 
With very few exceptions, their life cycle includes a brief, obligatory 
parasitic stage on a host organism, typically fish. Eggs develop into 
microscopic larvae (glochidia) within special gill chambers of the 
female. The female expels the mature glochidia, which must attach to an 
appropriate host species (generally a fish) to complete development. 
Host specificity varies among margaritiferids and unionids. Some 
species appear to use a single host, while others can transform on 
several host species. Following successful infestation, glochidia 
encyst (enclose in a cyst-like structure), remain attached to the host 
for several weeks, and then drop off as newly transformed juveniles. 
For further information on the life history of freshwater mussels, see 
Williams et al. 2008.
    Mussel biologists know relatively little about the specific life-
history requirements of the spectaclecase and sheepnose. Most mussels, 
including the spectaclecase and sheepnose, have separate sexes. Age at 
sexual maturity of the spectaclecase was estimated to be 4 to 5 years 
for males and 5 to 7 years for females, with sex ratios approximating 
50:50 (Baird 2000, p. 24). The spectaclecase life cycle includes a 
parasitic phase; however, despite extensive investigation, the host 
species is not yet known. The spectaclecase is thought to release 
glochidia from early April to late May in the Meramec and Gasconade 
Rivers, Missouri (Baird 2000, p. 26). Gordon and Smith (1990, p. 409) 
reported the species as producing two broods, one in spring or early 
summer and the other in the fall, also based on Meramec River 
specimens. In the Meramec and Gasconade Rivers, however, Baird (2000, 
pp. 26-27) found no evidence of two spawns in a given year.
    Age at sexual maturity for the sheepnose is unknown, but given its 
estimated longevity, probably occurs after a few years. The sheepnose 
is thought to be a short-term brooder, with egg fertilization taking 
place in early summer (Parmalee and Bogan 1998, p. 177; Williams et al. 
1998, p. 498), and glochidial release presumably occurring later in the 
summer. Hermaphroditism occurs in many mussel species (van der Schalie 
1966, p. 77), but is not known for the sheepnose. If hermaphroditism 
does occur in the sheepnose, it may explain the occurrence of small, 
but persistent populations over long periods of time.
    Spectaclecase and sheepnose glochidia are released in conglutinates 
(gelatinous structures containing numerous glochidia and analogous to 
cold capsules). Spectaclecase glochidia lack hooks (teeth-like 
structures that presumably function to pierce through the host's skin 
tissue) and are the smallest glochidia known of any North American 
freshwater mussel; they measure approximately 0.0024 inch (0.06 mm) in 
both length and height (Baird 2000, p. 22). Tens to hundreds of

[[Page 14916]]

thousands of glochidia may occur in each conglutinate. Based on 8 
Missouri spectaclecase specimens, the number of conglutinates released 
per female varied from 53 to 88, with a mean of 64.5 (Baird 2000, p. 
23). Total fecundity (reproductive potential, including glochidia and 
ova) in Baird's (2000, p. 27) Missouri study varied from 1.93 million 
to 9.57 million per female. In mussels, fecundity is related positively 
to body size and inversely related to glochidia size (Bauer 1994, pp. 
940-941). The reproductive potential of the spectaclecase is, 
therefore, phenomenal. However, the fact that extant populations are 
generally skewed towards larger adults strongly indicates that survival 
rates to the adult stage must be extraordinarily low.
    Researchers in Wisconsin observed female spectaclecase under 
boulders in the St. Croix River simultaneously releasing their 
conglutinates (Heath 2008a, pers. comm.). The spectaclecase 
conglutinates are entrained along a transparent, sticky mucous strand 
up to several feet in length (Lee and Hove 1997, p. 9). Baird (2000, p. 
29) observed the release of loose glochidia and small fragments of 
conglutinates. Based on his observations, he hypothesized that 
conglutinates sometimes contain mostly immature glochidia, and that 
conglutinates containing mostly immature glochidia may be aborted when 
disturbed.
    Sheepnose conglutinates are narrow and lanceolate in outline, solid 
and red or pink in color, and discharged in unbroken form (Oesch 1984, 
pp. 118-119). Discharge of sheepnose conglutinates have been observed 
in late July (Ortmann 1911, p. 306) and August (Williams et al. 2008, 
p. 498). Ortmann (1911, p. 306) described them as being pink and 
``lying behind the posterior end of the shell, which were greedily 
devoured by a number of minnows.'' Sheepnose glochidia are semicircular 
in outline, with the ventral margin obliquely rounded, hinge line long, 
and medium in size. The length (0.009 inch (0.23 mm)) is slightly 
greater than the height (0.008 inch (0.20 mm)) (Oesch 1984, p. 119). 
Several hundred glochidia probably occur in each conglutinate. Judging 
from the size of the glochidia, total fecundity (including glochidia 
and ova) per female sheepnose is probably in the tens of thousands.
    Like many freshwater mussels, the complex life histories of the 
spectaclecase and sheepnose have many vulnerable components that may 
prevent successful reproduction or recruitment of juveniles into 
existing populations. Glochidia must come into contact with a specific 
host species for their survival to be ensured. Without the proper host, 
the glochidia will perish. The host(s) for the spectaclecase is 
unknown, although more than 60 species of fish, amphibians, and 
crayfish have been tested in the lab during host suitability studies 
(Baird 2000, pp. 23-24; Henley and Neves 2006, p. 3; Hove et al. 2009, 
pp. 22-23; Hove et al. 1998, pp. 13-14; Hove et al. 2008, p. 4; Knudsen 
and Hove 1997, p. 2; Lee and Hove 1997, pp. 9-10). Two of 690 wild-
collected fish checked by Baird (2000, p. 24) had spectaclecase 
glochidia attached to their gills; these fish were the bigeye chub 
(Hybopsis amblops) and pealip redhorse (Moxostoma pisolabrum). However, 
these fish are not confirmed as hosts, because the encysted glochidia 
had not grown measurably and glochidial transformation was not observed 
(Baird 2000, p. 24). Spectaclecase populations are oftentimes highly 
aggregated (see Habitat) with many apparently even-aged individuals, 
suggesting that glochidia may excyst simultaneously from a host (Gordon 
and Layzer 1989, p. 19). Additional host work is underway to test the 
wild-collected fish species that were found with encysted spectaclecase 
glochidia (pealip redhorse and bigeye chub), as well as to test 
additional species of fish and other aquatic organisms for suitability. 
Host information is needed so that existing populations can be 
artificially cultured for potential population augmentation and 
reintroduction efforts.
    Little is known regarding host fish of the sheepnose. Until 
recently the only cited host for this species came from a 1914 report 
that found glochidia naturally attached to sauger (Sander canadense) in 
the wild. No confirmation of successful transformation was recorded in 
this early report (Surber 1913, p. 110; Wilson 1914, pp. 338-340). 
However, recent laboratory studies at the Genoa National Fish Hatchery, 
the University of Minnesota, and Ohio State University have 
successfully transformed sheepnose glochidia on fathead minnow 
(Pimephales promelas), creek chub (Semotilus atrromaculatus), central 
stoneroller (Campostoma anomalum), and brook stickleback (Culaea 
inconstans) (Watters et al. 2005, pp. 11-12; Brady 2008, pers. comm.; 
Watters 2008, pers. comm.). Although these are identified as suitable 
hosts in laboratory studies, natural interactions between the 
aforementioned fishes and the sheepnose seem rare and infrequent due to 
habitat preferences. Fish that frequent medium to large rivers near 
mussel beds, like the sauger, may act as hosts in the natural 
environment.

Habitat

    The spectaclecase generally inhabits large rivers, and is found in 
microhabitats sheltered from the main force of current. It occurs in 
substrates from mud and sand to gravel, cobble, and boulders in 
relatively shallow riffles and shoals with a slow to swift current 
(Baird 2000, pp. 5-6; Buchanan 1980, p. 13; Parmalee and Bogan 1998, p. 
50). According to Stansbery (1967, pp. 29-30), this species is usually 
found in firm mud between large rocks in quiet water very near the 
interface with swift currents. Specimens have also been reported in 
tree stumps, in root masses, and in beds of rooted vegetation (Oesch 
1984, p. 33). Similar to other margaritiferids, spectaclecase 
occurrences throughout much of its range tend to be aggregated (Gordon 
and Layzer 1989, p. 19), particularly under slab boulders or bedrock 
shelves (Baird 2000, p. 6; Buchanan 1980, p. 13; Parmalee and Bogan 
1998, p. 50), where they are protected from the current. Up to 200 
specimens have been reported from under a single large slab in the 
Tennessee River at Muscle Shoals, Alabama (Hinkley 1906, p. 54). Unlike 
most species that move about to some degree, the spectaclecase may 
seldom if ever move except to burrow deeper and may die from stranding 
during droughts (Oesch 1984, p. 17). At least one recent study, 
however, indicated that spectaclecase can be quite active; 
specifically, relocated individuals moved to more suitable habitat 
(Dunn et al. 1999, pp.175, 177).
    The sheepnose is a larger-stream species occurring primarily in 
shallow shoal habitats with moderate to swift currents over coarse sand 
and gravel (Oesch 1984, p. 121). Habitats with sheepnose may also have 
mud, cobble, and boulders. Sheepnose in larger rivers may occur at 
depths exceeding 6 m (Williams et al. 2008, p. 498).

Genetics

    A recent genetic study (Monroe et al. 2007, pp. 7-13) indicates 
that much of the remaining genetic variability in the spectaclecase is 
represented in each of the remaining large populations, and that these 
populations do not appear to differ significantly from one another.
    In contrast, genetics studies of the sheepnose (Roe 2011, pers. 
comm.) indicate that extant populations appear to be genetically 
isolated from each other. The conservation implications from this study 
are that each of its populations should be managed as independent 
entities for purposes of captive rearing and propagation until evidence 
indicates a particular

[[Page 14917]]

population may benefit from the introduction of novel genetic 
information (Roe 2011, pers. comm.).

Species Distribution

    We use the term ``population'' here in a geographical and not 
genetic sense, defining it as all individuals of the spectaclecase or 
sheepnose living in one stream. Using the term in this way allows the 
status, trends, and threats to be discussed comparatively across 
streams where the species occur. In using this term we do not imply 
that their populations are currently reproducing and recruiting or that 
they are distinct genetic units. We considered populations of the 
spectaclecase and sheepnose as extant if live or fresh-dead specimens 
have been observed or collected since 1990. A ``population cluster'' 
refers to where two or more adjacent stream populations of a species 
occur without a barrier (for example, a dam and impoundment) between 
them.
    Following are generalized sets of criteria that were used to 
categorize the relative status of populations of spectaclecase and 
sheepnose. The status of a population is considered ``improving'' if: 
(1) There is evidence that habitat degradation appears insignificant, 
(2) live or fresh dead mussel abundance has improved during post-1990 
surveys, or (3) ample evidence of recent recruitment has been 
documented during post-1990 surveys. The status of a population is 
considered ``stable'' if: (1) There is little evidence of significant 
habitat loss or degradation, (2) live or fresh dead mussel abundance 
has been fairly consistent during post-1990 surveys, or (3) evidence of 
relatively recent recruitment has been documented during post-1990 
surveys. The status of a population is considered ``declining'' if: (1) 
There is ample evidence of significant habitat loss or degradation, (2) 
live or fresh dead mussel numbers have declined during recent surveys, 
or (3) no evidence of relatively recent recruitment has been documented 
during recent surveys. The status of a population is considered 
``extirpated'' if: (1) All known suitable habitat has been destroyed, 
or (2) no live or fresh dead mussels of any age have been located 
during recent surveys. The status of a population is considered 
``unknown'' if the available information is inadequate to place the 
population in one of the above four categories. In a few cases, 
additional information not listed above may have been used to 
categorize a population.

Spectaclecase Historical Range and Distribution

    The spectaclecase occurred historically in at least 44 streams in 
the Mississippi, Ohio, and Missouri River basins (Butler 2002b, p. 6, 
Heath 2008, pers. comm.). Its distribution comprised portions of 14 
States (Alabama, Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, 
Minnesota, Missouri, Ohio, Tennessee, Virginia, West Virginia, and 
Wisconsin). Historical occurrences by stream system (with tributaries) 
include the following:
     Upper Mississippi River system (Mississippi River (St. 
Croix), Chippewa, Rock, Salt, Illinois (Des Plaines, Kankakee Rivers), 
Meramec (Bourbeuse, Big Rivers), Kaskaskia Rivers; Joachim Creek);
     Lower Missouri River system (Missouri River (Platte, River 
Aux Vases, Osage (Sac, Marais des Cygnes Rivers), Gasconade (Osage 
Fork, Big Piney River) Rivers));
     Ohio River system (Ohio River (Muskingum, Kanawha, Green, 
Wabash Rivers));
     Cumberland River system (Cumberland River (Big South, 
Caney Fork; Stones, Red Rivers));
     Tennessee River system (Tennessee River (Holston, 
Nolichucky, Little, Little Tennessee, Clinch (Powell River), 
Sequatchie, Elk, Duck Rivers)); and
     Lower Mississippi River system (Mulberry, Ouachita 
Rivers).

Spectaclecase Current Range and Distribution

    Extant populations of the spectaclecase are known from 20 streams 
in 11 States (Butler 2002b, p. 7). These include the following stream 
systems (with tributaries):
     Upper Mississippi River system (Mississippi River (St. 
Croix, Meramec (Bourbeuse, Big Rivers) Rivers));
     Lower Missouri River system (Osage, Sac, Gasconade (Osage 
Fork, Big Piney River) Rivers);
     Lower Ohio River system (lowermost Ohio River (Kanawha, 
Green Rivers));
     Cumberland River system (Cumberland River);
     Tennessee River system (Tennessee River (Nolichucky, 
Clinch, Duck Rivers)); and
     Lower Mississippi River system (Mulberry, Ouachita 
Rivers).
    The 20 extant spectaclecase populations occur in the following 11 
States (with streams):
     Alabama (Tennessee River),
     Arkansas (Mulberry, Ouachita Rivers),
     Illinois (Mississippi, Ohio Rivers),
     Iowa (Mississippi River),
     Kentucky (Ohio, Green, Cumberland Rivers),
     Minnesota (Mississippi, St. Croix Rivers),
     Missouri (Mississippi, Meramec, Bourbeuse, Big, Gasconade, 
Sac, Osage, Big Piney Rivers; Osage Fork),
     Tennessee (Tennessee, Clinch, Nolichucky, Duck Rivers),
     Virginia (Clinch River),
     West Virginia (Kanawha River), and
     Wisconsin (Mississippi, St. Croix Rivers).

Spectaclecase Population Estimates and Status

    Based on historical and current data, the spectaclecase has 
declined significantly rangewide and is now known from only 20 of 44 
streams (Table 1), representing a 55 percent decline. The species is 
presumed extirpated from thousands of river miles and from numerous 
reaches of habitat in which it occurred historically, including long 
reaches of upper Mississippi, Ohio, Cumberland, and Tennessee Rivers 
and many other streams and stream reaches. Of the 20 extant 
populations, 6 are represented by only one or two recent specimens each 
and are likely declining and some may be extirpated. Populations in 
Mississippi and Clinch Rivers have recently experienced significant 
population declines. Most surviving populations face significant 
threats and with few exceptions are highly fragmented and restricted to 
short stream reaches. The spectaclecase is considered extirpated from 
Indiana, Kansas, and Ohio. Reports of the spectaclecase from 1877 in 
the Blue and Elkhorn Rivers, Nebraska are not considered valid (Fritz 
2010, pers. comm.). The only relatively strong populations remaining 
are in the Meramec and Gasconade Rivers in Missouri and in the St. 
Croix River in Minnesota and Wisconsin.

[[Page 14918]]



                Table 1--Spectaclecase Status in All Streams of Historical or Current Occurrence
----------------------------------------------------------------------------------------------------------------
                                                                           Date of last live
          River basin                  Stream          Current  status       or fresh dead          Comments
                                                                              observation
----------------------------------------------------------------------------------------------------------------
Upper Mississippi River........  Mississippi River.  Declining..........  2009
                                 St. Croix River...  Stable.............  2008
                                 Chippewa River....  Extirpated.........  1989
                                 Rock River........  Extirpated.........  ~1970
                                 Salt River........  Extirpated.........  1980
                                 Illinois River....  Extirpated.........  ~1914
                                 Des Plaines River.  Extirpated.........  ~1921
                                 Kankakee River....  Extirpated.........  1906
                                 Meramec River.....  Stable.............  2003
                                 Bourbeuse River...  Stable.............  1997
                                 Big River.........  Stable.............  2002
                                 Kaskaskia River...  Extirpated.........  ~1970
                                 Joachim Creek.....  Extirpated.........  ~1965
Lower Missouri River...........  Missouri River....  Extirpated.........  ~1914
                                 Platte River......  Extirpated.........  ~1917
                                 River Aux Vases...  Extirpated.........  ~1974
                                 Osage River.......  Unknown............  2010
                                 Sac River.........  Declining..........  2001
                                 Marais des Cygnes   Extirpated.........  Unknown............  Relic shell
                                  River.                                                        observed in
                                                                                                1998.
                                 Gasconade River...  Stable.............  2007
                                 Big Piney River...  Unknown............  2004
                                 Osage Fork........  Unknown............  1999
Ohio River.....................  Ohio River........  Declining..........  1994...............  Single individual
                                                                                                observed.
                                 Muskingum River...  Extirpated.........  Unknown............  Relic shell
                                                                                                observed in
                                                                                                1995.
                                 Kanawha River.....  Unknown............  2005...............  Two live
                                                                                                individuals
                                                                                                observed.
                                 Green River.......  Unknown............  2006
                                 Wabash River......  Extirpated.........  1970
Cumberland River...............  Cumberland River..  Unknown............  2008...............  Single individual
                                                                                                observed.
                                 Big South Fork....  Extirpated.........  1911
                                 Caney Fork........  Extirpated.........  1988
                                 Stones River......  Extirpated.........  1968
                                 Red River.........  Extirpated.........  1966
Tennessee River................  Tennessee River...  Unknown............  2001
                                 Holston River.....  Extirpated.........  1981
                                 Nolichucky River..  Unknown............  1991
                                 Little River......  Extirpated.........  ~1911
                                 Little Tennessee    Extirpated.........  Unknown............  Relic shell
                                  River.                                                        observed in
                                                                                                1980, previous
                                                                                                record
                                                                                                archaeological.
                                 Clinch River......  Declining..........  2010
                                 Powell River......  Extirpated.........  ~1978
                                 Sequatchie River..  Extirpated.........  ~1925
                                 Elk River.........  Extirpated.........  Unknown............  Relic shell
                                                                                                observed in
                                                                                                1998.
                                 Duck River........  Unknown............  Early 2000s........  Single individual
                                                                                                observed.
Lower Mississippi River........  Mulberry River....  Unknown............  ~1995..............  Single individual
                                                                                                observed.
                                 Ouachita River....  Declining..........  1990s..............  Two individuals
                                                                                                observed.
----------------------------------------------------------------------------------------------------------------

    Based on collections made more than 100 years ago, the 
spectaclecase was historically widespread and locally common in many 
streams rangewide. The spectaclecase is often absent from 
archaeological shell middens (Morrison 1942, p. 353) and is generally 
difficult to find due to its habit of occurring under rocks or ledges 
and burrowing deep into the substrate (Parmalee 1967, p. 25). 
Therefore, the chance of casually finding the species where population 
numbers are low is remote.
    The spectaclecase was considered a rare species by mussel experts 
as early as 1970 (Stansbery 1970, p. 13), when the first attempt was 
made to compile a list of imperiled mussels. The spectaclecase is 
considered widely distributed but absent from many areas where it 
formerly occurred (Cummings and Mayer 1992, p. 22). The American 
Malacological Union and American Fisheries Society consider the 
spectaclecase to be threatened (Williams et al. 1993, p. 10). Six of 
the 20 streams (or big river reaches) considered to harbor extant 
populations of the spectaclecase are represented by one or two recent 
specimens (for example, Ohio, Kanawha, Cumberland, Duck, Ouatchita, and 
Mulberry Rivers), exemplifying the species' imperiled status rangewide.
    In some streams, the last reported records for the spectaclecase 
occurred decades ago (for example, Rock, Des Plaines, Kaskaskia, 
Platte, Wabash, Stones, Red, and Little Rivers; River Aux Vases; Big 
South Fork). Parmalee (1967, p. 25) considered the spectaclecase to be 
``rare and of local occurrence'' in Illinois in the 1960s, but that it 
had ``[a]pparently already been extirpated from the Illinois and 
Kankakee Rivers.'' The only records known from some streams are relic 
specimens collected around 1975 (for example, Marais des Cygnes, 
Muskingum, and Elk Rivers).
    Although quantitative historical abundance data for the 
spectaclecase is rare, generalized relative abundance (the percent 
abundance of a species, divided by the total abundance of all mussel 
species combined) was sometimes noted in the historical literature and 
can be

[[Page 14919]]

inferred from museum lots. The following is a summary of what is known 
about the relative abundance and trends of presumably extant 
spectaclecase populations by stream system.

Upper Mississippi River System

    The spectaclecase was historically known from 13 streams in the 
upper Mississippi River system. Currently, in addition to the mainstem, 
only four streams in the system are thought to have extant 
spectaclecase populations.
    Mississippi River mainstem: In 1907, Bartsch found spectaclecase at 
approximately 9 of the 140 sampled sites from what are now Mississippi 
River Pools (MRP) 9 to 22 (Havlik 2001b, p. 10). Grier (1922, p. 11) 
did not find spectaclecase in sampled portions of MRP 4 to 6. The team 
of van der Schalie and van der Schalie (1950, p. 456), reporting on 
studies from the upper Mississippi River to the Missouri River mouth, 
stated that no live spectaclecase were found in their study of 254 
sites during 1930-31. Havlik and Stansbery (1977, p. 12) thought the 
spectaclecase had disappeared from MRP 8 by the 1920s. Thiel (1981, p. 
10) found only shell material in MRP 11 in a survey that spanned MRP 3 
to 11 conducted during 1977 to 1980. Whitney et al. (1997, p. 12) 
recorded a single individual during 1994-95 in MRP 15, for a density of 
0.004 per square foot (sq. ft) (0.04 per square meter (sq. m)). Helms 
(2008, p. 8) found eight live individuals and numerous shells during a 
search of MRP 19, representing the most recent and numerous collection 
of the species in the Mississippi River.
    The spectaclecase is thought to be extant in at least four pools of 
the Mississippi River mainstem, albeit in very low numbers. Records 
include MRP 15 (Quad Cities area, Illinois and Iowa; in 1998), MRP 16 
(Muscatine area, Iowa and Illinois in 1997), MRP 19 (Burlington area, 
Illinois and Iowa in 2009), and MRP 22 (Quincy, Illinois and Hannibal, 
Missouri, area in 1996). Populations may still persist in MRP 9 and 10 
where specimens were found in the 1980s (Heath 2010a, pers. comm.). 
Only a relic spectaclecase shell was found in MRP 3 above the St. Croix 
River confluence in 2001, and none were found in subsequent surveys 
(Kelner 2008, pers. comm.). In general, spectaclecase population levels 
in the upper Mississippi River appear to have always been fairly small 
and difficult to locate, and are now of questionable long-term 
persistence.
    St. Croix River: The northernmost and one of the three most 
significant extant populations of the spectaclecase occurs in the St. 
Croix River, Minnesota and Wisconsin. The population is primarily found 
in the middle reaches of the river in Chisago and Washington Counties, 
Minnesota, and Polk and St. Croix Counties, Wisconsin (river miles (RM) 
16 to 118). Seventeen live spectaclecase were collected from river mile 
16 in the St. Croix River in 1994 (Dunn et al. 1999, p. 174). Havlik 
(1994, p. 19) reported spectaclecase in the St. Croix Wild River State 
Park portion of the river (approximately RM 62 to 65) and the 
reproducing population below the St. Croix Falls Dam at St. Croix 
Falls, Wisconsin (dam located at approximately RM 52). Additional 
survey work in the lower river at Afton State Park (approximately RM 7 
to 9) failed to find the spectaclecase (Havlik 1994, p. 19).
    Hornbach (2001, p. 218) reported 68 live specimens from 4 of 16 
river reaches. Relative abundance for the spectaclecase varied from 
0.67 percent from RM 78 to 92 (20 live spectaclecase among 17 species 
collected), 0.008 percent from RM 63 to 78 (41 live, 24 species), 
0.0006 percent from RM 42 to 52 (6 live, 33 species), and 0.003 percent 
from RM 40 to 42 (1 live, 21 species). Reaches where the spectaclecase 
is extant are fragmented by the pool formed from the power dam at St. 
Croix Falls.
    Baird (2000, p. 70) presented a length-frequency histogram for the 
spectaclecase in the St. Croix River using data from an unpublished 
1989 study. The 962 specimens were fairly evenly distributed over the 
length scale, indicating multiple age classes including healthy numbers 
of young spectaclecase recruiting into the population. Baird (2000, p. 
70) used growth curves determined from his Missouri study of the 
species to estimate the ages of spectaclecase of known size in the St. 
Croix River. The percentage of newly recruited individuals (less than 
or equal to 10 years of age) in the St. Croix was 40 percent--
considerably higher than that noted from the Gasconade (10.4 percent) 
and Meramec (2.8 percent) Rivers in Missouri, two other streams with 
abundant spectaclecase populations that he studied. The St. Croix 
spectaclecase population, while among the largest known, may also be 
the healthiest based on this metric. The spectaclecase is currently 
distributed from RM 17 to 118 and appears to be recruiting from RM 17 
to 54 (downstream of the St. Croix Falls Dam) (Heath 2008, pers. 
comm.).
    The long-term health of mussel populations in the St. Croix may be 
in jeopardy, however. Hornbach et al. (2001, pp. 12-13) determined that 
juvenile mussel density had suffered a statistically significant 
decline at three of four lower St. Croix sites sampled in the 1990s and 
in 2000. Zebra mussels also threaten the spectaclecase and other mussel 
populations in the lower St. Croix River. A 2000 survey at 20 sites on 
the lowermost 24 miles of the St. Croix River estimated that nearly one 
percent of the mussels were infested with zebra mussels (Kelner and 
Davis 2002, p. 36).
    Meramec River: The Meramec River flows into the Mississippi River 
downstream of St. Louis in east-central Missouri. Its spectaclecase 
population represents one of the best remaining rangewide. In the late 
1970s, Buchanan (1980, p. 13) reported this species from 31 sites, 19 
with live individuals. Live or fresh dead individuals occurred from RM 
17.5 to 145.7. Buchanan (1980, p. 6) considered it to be common in the 
lower 108 miles (174 km) of the Meramec River, but locally abundant 
from RM 17.5 to 84. In 1997, Roberts and Bruenderman (2000, pp. 39, 
44), using similar sampling methods as Buchanan (1980, pp. 4-5), 
resurveyed the Meramec River system and collected spectaclecase from 23 
sites, 19 of which had live individuals. They found the largest 
populations between RM 56.7 and 118.8. Among 17 sites where 
spectaclecase were found during both surveys, the species was less 
abundant at 9 sites and more abundant at 5 sites in 1997. At three 
sites, only relic shells were found during both surveys.
    In the 1970s, Buchanan (1980, p. 10) reported finding 456 live 
individuals among the 17 shared sites, whereas Roberts and Bruenderman 
(2000, p. 44) recorded only 198. A reduction in spectaclecase numbers 
(260 to 33) at RM 59.5 accounted for most of the overall decrease in 
abundance between the studies. Confounding the decrease in numbers 
among shared survey sites, Roberts and Bruenderman (2000, p. 44) 
surveyed three sites between RM 56.7 and 118.8 that were unsampled by 
Buchanan (1980, pp. 1-69) and found 500, 538, and 856 live 
spectaclecase. The most specimens found at a single site in the earlier 
study was 260 (RM 59.5). Currently, the population in the Meramec River 
stretches over much of the mainstem, a distance of more than 100 miles 
(161 km) from RM 18.5 to 120.4.
    The spectaclecase represented 28 percent of all mussels sampled in 
the Meramec River in 1997 (Roberts and Bruenderman 2000, p. 39). Baird 
(2000, pp. 62, 68,77) extensively studied the demographics of the 
Meramec River spectaclecase population in the late

[[Page 14920]]

1990s. The mean estimated age of the population was 32 years. 
Individuals less than 10 years of age comprised only 2.8 percent of the 
Meramec population sampled (a total of 2,983 individuals). At the four 
sites he intentionally selected for their large spectaclecase 
populations, densities ranged from 0.01 to 0.12 per sq. ft (0.1 to 1.3 
per sq. m) while estimated population numbers at these sites ranged 
from 933 to 22,697. Baird (2000, p. 71) thought that conditions for 
spectaclecase recruitment in the Meramec had declined in the past 20 to 
30 years, but the causes were undetermined. The prevalence of larger 
adults in the Meramec population may be cause for concern, as it 
appears to indicate a low level of recruitment in the population.
    Bourbeuse River: The Bourbeuse River is a northern tributary of the 
Meramec River joining it at RM 68. Its spectaclecase population was 
sampled in 1997 at a single site (RM 10.3), and 7 live individuals were 
found (Roberts and Bruenderman 2000, p. 91). Sampling near the mouth 
(RM 0.4), Buchanan (1980, p. 16) found only relic shells. The Bourbeuse 
population is probably dependent on the much larger Meramec population 
for long-term sustainability.
    Big River: Another Meramec tributary with a population of the 
spectaclecase, the Big River flows northward into the Meramec River at 
RM 38. The spectaclecase is only known from the lower end (RM 1.3), 
where 14 live specimens were found in 1997 (Roberts and Bruenderman 
2000, p. 96). At RM 0.4, Buchanan (1980, p. 13) found only relic 
shells. Similar to the Bourbeuse River population, the population in 
the Big River is probably dependent on the much larger Meramec 
population for sustainability. The Meramec River system, including the 
lower Bourbeuse, lower Big, and Meramec River mainstems, can be 
considered a single spectaclecase population cluster.

Lower Missouri River System

    The spectaclecase was historically known from 10 streams in the 
Missouri River system. Currently, only five of these streams are 
thought to have extant populations.
    Osage River: The spectaclecase was considered extirpated from the 
Osage River in the 2002 status review of the species (Butler 2002b, pp. 
57-58). However, fresh dead shells were collected at three sites during 
a 2001 survey (Ecological Specialists, Inc. 2003, chapter 3, p. 12) and 
8 live individuals were found at a site in the lower Osage River in 
2010 (Roberts 2011, pers. comm.). The status of the species in the 
Osage River is unknown.
    Sac River: The Sac River is a large tributary to the Osage River. 
The spectaclecase was considered extirpated in the 2002 status review 
of the species (Butler 2002b). However, three old, live individuals 
were collected at two sites during a survey of the Sac River in 2004 
(Hutson and Barnhart 2004, p. 17). The same survey revealed 
``numerous'' relic shells from six other sites, indicating that the 
spectaclecase may have been relatively abundant at one time. Prior to 
the 2004 survey, the spectaclecase had not been collected from this 
river since 1978 (Bruenderman 2001, pers. comm.). Given the age of the 
live individuals and the abundance of shell material, Hutson and 
Barnhart (2004, p. 17) predicted the species would ``soon be 
extirpated'' from the river.
    Gasconade River: The Gasconade River is a southern tributary of the 
Missouri River in south-central Missouri and flows into the mainstem 
east of Jefferson City. When Stansbery (1970, p. 13) included this 
species in the first compiled list of imperiled mussels, he noted that 
``the only population of substantial size presently known is found in 
the Gasconade River.'' In 1994, Buchanan found more than 1,000 
individuals between RM 7 and 84 (Buchanan 1994, pp. 5, 8-13). Today, 
one of the three best spectaclecase populations remaining rangewide 
occurs in the Gasconade. The spectaclecase population occurs over 
approximately 200 miles (322 km) of the mainstem from RM 4.9 upstream 
(Bruenderman et al. 2001, p. 54). Baird (2000, pp. 61, 71) studied the 
demographics of the Gasconade River spectaclecase population in the 
late 1990s. Based on his limited number of sampling sites, this species 
comprised about 20 percent of the entire mussel fauna in this system. 
The mean estimated age of the population was 25 years. Individuals less 
than 10 years of age comprised 10.4 percent of the Gasconade population 
sampled (n = 2,111), indicating a significant level of recent 
recruitment.
    Historically, Stansbery (1967, p. 29) noted that ``[t]he size of 
some aggregation[s] * * * is impressive,'' and that ``the number of 
individuals may reach a density of well over a dozen per square foot.'' 
Both statements are probably in reference to the Gasconade River, 
Missouri population, which he had described in the text of his note. 
Densities at the four sites Baird (2000, pp. 61, 71) intentionally 
selected for their large spectaclecase populations ranged from 0.03 to 
0.06 per sq. ft (0.3 to 0.6 per sq. m); estimated population numbers at 
these selected sites ranged from 2,156 to 4,766. Baird (2000, p. 71) 
thought that conditions for spectaclecase recruitment in the Gasconade 
River had declined in the past 20 to 30 years, but the causes were 
undetermined.
    Big Piney River: The Big Piney River, a southern tributary of the 
Gasconade River, harbors a small population of the spectaclecase. 
Although overlooked during a 1999 survey (Bruenderman et al. 2001, pp. 
14, 28), 15 individuals were collected from the lower mainstem (RM 24) 
in 2004 (Barnhart et al. 2004, p. 5). The status of the population is 
unknown, but it is probably dependent on the much larger source 
population in the Gasconade River for sustainability (McMurray 2008, 
pers. comm.).
    Osage Fork: The Osage Fork is a southwestern headwater tributary of 
the Gasconade River. The spectaclecase is known from the lower portion 
of this Gasconade River tributary, specifically from RM 13.9. Sampling 
in the Osage Fork in 1999 yielded 26 live individuals from this site 
(Bruenderman et al. 2001, p. 9). Relative abundance of the 
spectaclecase in the Osage Fork was 3.9 percent, and catch-per-unit 
effort was 1.3 per person-hour. This population is thought to be 
stable, but it may also be dependent on the much larger source 
population in the Gasconade River for long-term sustainability. The 
Gasconade River system, including the lower Big Piney, lower Osage 
Fork, and Gasconade mainstems, can be considered a single population 
cluster.

Ohio River System

    The spectaclecase's continued existence in the Ohio River is 
extremely uncertain. Once known from five rivers, it has been 
extirpated from two, and two of the remaining three are recently 
represented by only one or two individuals each.
    Ohio River: The Ohio River is the largest eastern tributary of the 
Mississippi River, with its confluence marking the divide between the 
upper and lower portions of the Mississippi River system. Historically, 
the spectaclecase was documented from the Ohio River from the vicinity 
of Cincinnati, Ohio, to its mouth. Although no specimens are known from 
the mainstem upstream of Cincinnati, populations are known from two 
upstream tributaries, the Muskingum and Kanawha Rivers. Nearly all 
spectaclecase records from the Ohio River were made around 1900 or 
before (Schuster 1988, p. 186). The only recent record is for a single 
live individual found in an abandoned gill net near the Illinois shore 
in 1994 (Cummings 2008a,

[[Page 14921]]

pers. comm.). If a population of the spectaclecase continues to occur 
in the Ohio River, its future persistence is extremely doubtful and 
continued existence seriously threatened by the exotic zebra mussel.
    Kanawha River: The Kanawha River is a major southern tributary of 
the Ohio River that drains much of West Virginia. The spectaclecase was 
not known from this stream until 2002, when a single, very old, live 
individual was discovered near Glasgow, Kanawha County (Zimmerman 2002, 
pers. comm.). Another live individual was found in the same vicinity in 
2005, as well as two additional weathered shells in 2006 (Clayton 
2008a, pers. comm.). This site is approximately 20 miles (32.2 km) 
downstream of Kanawha Falls, below which is the only significant mussel 
bed known from the Kanawha River. It is doubtful that a recruiting 
spectaclecase population occurs in the Kanawha River due to the small 
number of individuals found and their advanced age.
    Green River: The Green River is a lower Ohio River tributary in 
west-central Kentucky. The spectaclecase has been collected sparingly 
in the Green River. That it was not reported in early collections made 
in the system is indicative of the difficulty in finding specimens 
(Price 1900, pp. 75-79). Stansbery (1965, p. 13) was the first to find 
it in the mid-1960s at Munfordville, Hart County, where he reported 47 
mussel species collected over a several-year period in the early 1960s. 
More recently, from 1987 to 1989, Cicerello and Hannan (1990, p. 20) 
reported single fresh dead specimens at six sites and relic specimens 
from an additional five sites in Mammoth Cave National Park (MCNP). A 
single specimen was recorded from MCNP, Edmonson County, in 1995. 
Sampling conducted from 1996 to 1998 located fresh dead specimens at 
two sites above MCNP, with a relic shell at a third site farther 
upstream (Cicerello 1999, pp. 17-18). At least one fresh dead specimen 
was reported from MCNP in 2001, as well as several live individuals in 
2005 and 2006 (Layzer 2008a, pers. comm.).
    A small spectaclecase population remains in the upper Green River 
from below Lock and Dam 5 upstream through MCNP, Edmonson County, into 
western Hart County. Most recent specimens have been reported from the 
upstream portion of this reach, where it is generally distributed from 
MCNP upstream to western Hart County. Its distribution is much more 
sporadic and localized in the lower portion of this reach due to the 
pooling effect of two locks and dams (5 and 6). In 2001, a concerted 
effort (approximately 15 person-hours) to locate rare mussels below 
Lock and Dam 5 and at other sites downstream failed to find 
spectaclecase (live or shell), although a fresh dead shell had been 
collected in this area in 1993 (Cicerello 2008, pers. comm.). The 
occurrence of variable-sized individuals in the 1990s indicates 
different year classes but not necessarily recent recruitment 
(Cicerello 2008, pers. comm.). The long-term sustainability of the 
Green River population, primarily limited to an approximately 15-mile 
(24-km) reach of the river, is therefore questionable, and its status 
is unknown.

Cumberland River System

    With few exceptions, most records of the spectaclecase in the 
Cumberland River system were made before the 1920s. It was historically 
known from the mainstem and four tributaries but appears currently to 
be restricted to the lowermost Cumberland River a few miles above its 
confluence with the Ohio River.
    Cumberland River mainstem: The Cumberland River is a large southern 
tributary of the lower Ohio River. The spectaclecase was considered 
``not rare'' in the Cumberland River by Hinkley and Marsh (1885, p. 6), 
whereas it was found at six sites by Wilson and Clark (1914, pp. 17, 
19) during their survey primarily for commercial species in the 
Cumberland River system. In a 1947-49 survey of the Kentucky portion of 
the upper Cumberland River, Neel and Allen (1964, p. 453) reported live 
specimens only from one of six mainstem sites that they sampled below 
Cumberland Falls. Neel and Allen (1964, p. 432) considered it to be 
``uncommon'' in the lower Cumberland River (where they did not sample), 
a statement possibly based on its sporadic occurrence as reported by 
Wilson and Clark (1914, pp. 17, 19). One of the last mainstem records 
is that of a single live specimen found in the cold tailwaters of Wolf 
Creek Dam, Kentucky, near the Tennessee border in 1982 (Miller et al. 
1984, p. 108). This was one of only two live mussels found during a 
survey of the dewatered river reach below the dam, the mussel community 
having been eliminated from decades of cold water releases. The most 
recent record is of a single live individual found at RM 10 in Kentucky 
below Barkley Lock and Dam in 2008 (Fortenbery 2008, p. 9). A thorough 
search of the area yielded no additional individuals.

Tennessee River System

    The spectaclecase was originally known from the Tennessee River and 
nine of its stream systems. Ortmann (1924, p. 60) reported that the 
spectaclecase was ``frequent * * * in the upper Tennessee,'' while 
acknowledging in an earlier paper (Ortmann 1918, p. 527) that it was 
locally abundant in parts of the upper Tennessee River system, but 
noted that it was ``generally regarded as a rare species'' rangewide.
    Hundreds of miles of large river habitat on the Tennessee mainstem 
have been converted under nine reservoirs, with additional dams 
constructed in tributaries historically harboring this species (for 
example, Clinch, Holston, and Elk Rivers). Watters (2000, p. 262) 
summarizes the tremendous loss of mussel species from various reaches 
of the Tennessee. The spectaclecase is now known only from the 
Tennessee mainstem and three of its tributaries. Despite this fact, the 
Tennessee River system continues to represent one of the last 
strongholds of the spectaclecase rangewide.
    Tennessee River mainstem: The Tennessee River is the largest 
tributary of the Ohio River, draining portions of seven states. The 53-
mile (85-km) stretch of river in northwestern Alabama collectively 
referred to as the Muscle Shoals historically harbored 69 species of 
mussels, making it among the most diverse mussel faunas ever known 
(Garner and McGregor 2001, p. 155). The historical spectaclecase 
population in this reach was thought to be phenomenal given the amount 
of historical habitat that was available and literature accounts of the 
period. Hinkley (1906, p. 54), in 1904, considered the spectaclecase 
``plentiful,'' noting 200 individuals under a single slab boulder. 
Twenty years later, Ortmann (1925, p. 327) stated that ``this species 
must be, or have been, abundant'' at Muscle Shoals based on the 
``considerable number of dead shells'' he observed. In these quotes he 
predicted the demise of the spectaclecase. The construction of three 
dams (Wilson in 1925, Wheeler in 1930, Pickwick Landing in 1940) 
inundated most of the historical habitat, leaving only small habitat 
remnants (Garner and McGregor 2001, p. 155). The largest remnant 
habitat remaining is the Wilson Dam tailwaters, a reach adjacent to and 
downstream from Florence, Alabama.
    With the exception of 1976-78 when it was ``collected 
infrequently'' from below Wilson Dam (Gooch et al. 1979, p. 90), no 
collections of the spectaclecase were reported at Muscle Shoals from 
1931 to 1995 despite surveys conducted in 1956-57, 1963-64, and 1991 
(Garner and McGregor 2001, p. 156).
    Elsewhere along the Tennessee mainstem, a specimen was recently

[[Page 14922]]

reported from the Guntersville Dam tailwaters in northern Alabama 
(Butler 2002b, p. 17). From 1997-99, Ohio State University Museum 
(OSUM) records reflect that 10 live, 1 fresh dead, and 4 relic 
spectaclecase were reported from three sites in this river reach. The 
species is found only occasionally in the lower Tennessee River below 
Pickwick Landing Dam in southeastern Tennessee, having been unreported 
in various surveys (for example, Scruggs 1960, p. 12; van der Schalie 
1939, p. 456). Yokley (1972, p. 61) considered it rare, having only 
found fresh dead specimens in his 3-year study. Hubbs and Jones (2000, 
p. 28) reported two live specimens found in 1998 at RM 170, Hardin 
County. The current status of these small populations is unknown 
(Garner 2008, pers. comm.; Hubbs 2008, pers. comm.).
    Nolichucky River: The Nolichucky River is a tributary of the lower 
French Broad River, in the upper Tennessee River system in North 
Carolina and Tennessee. The spectaclecase population in this river was 
once sizable, judging from museum lots (for example, 23 fresh dead, 
OSUM 1971:0372). Sampling at 41 Nolichucky River sites in 1980, 
Ahlstedt (1991, pp. 136-137) reported 8 live spectaclecase from 6 sites 
between RM 11.4 to 31.9. A small population of the spectaclecase also 
persists in a relatively short reach of the lower river (Ahlstedt 2008, 
pers. comm.). The current status of the Nolichucky River population is 
unknown.
    Clinch River: The Clinch River is a major tributary of the upper 
Tennessee River in southwestern Virginia and northeastern Tennessee. 
B[ouml]pple and Coker (1912, p. 9) noted numerous spectaclecase shells 
in muskrat middens in a portion of the Clinch that is now inundated by 
Norris Reservoir. Ortmann (1918, p. 527) reported the spectaclecase as 
being locally abundant in the lower Clinch River, again in an area 
mostly flooded by Norris Reservoir. Oddly, he failed to find this 
species upstream of Claiborne County, yet, in later years, one of the 
spectaclecase's largest known populations was identified in this reach. 
The species was locally common at sites in the upper Clinch River, 
according to OSUM records from the 1960s. Ahlstedt (1991, p. 98) 
considered this species to be relatively rare in the Clinch River based 
on survey work conducted during 1978 to 1983. He recorded 78 live 
specimens from 22 sites between RM 151 and 223, for an average of 3.5 
per site. The spectaclecase population reported by Ahlstedt (1991a, pp. 
89-90) from the lower Clinch River between Melton Hill and Norris Dam 
(11 specimens from 4 sites between RM 45 and 73) was considered to be 
small but stable. Once considered abundant in the Clinch River at 
Speers Ferry, Scott County, Virginia (Bates and Dennis 1978, pp. 18-
19), the species is now extremely rare at this site (Neves 1991, p. 
264).
    Currently, the species is locally common in the Tennessee River 
system only in the upper Clinch River, and populations are primarily 
restricted to the Tennessee portion of that stream. Low numbers (0.02 
per sq. ft (0.2 per sq. m)) were detected in quantitative sampling 
(428; 2.7 sq. ft (0.25 sq. m) quadrats) in 1994 (Ahlstedt and 
Tuberville 1997, pp. 73, 81). Three individuals were collected at RM 
223.6 in Virginia in 2005 and a few more live spectaclecase were found 
in 2010 (Watson 2011, pers. comm.). One old individual was collected in 
2007 at RM 270.8, representing the farthest upstream record for the 
species (Eckert 2008, pers. comm.). The upper Clinch River population 
is considered to be reproducing, with fairly young individuals 
occasionally found, but overall the population appears to be declining 
(Ahlstedt 2008, pers. comm.). The recent occurrence of a disjunct 
population in the lower Clinch River (separated from the upper Clinch 
River population by Norris Reservoir) was recently verified (Fraley 
2008a, pers. comm.). The specimens sampled likely recruited since the 
Norris Dam gates closed in 1936 (Fraley 2008a, pers. comm.), despite 
the cold tailwaters that destroyed the majority of the mussel fauna in 
this once incredibly diverse river reach.
    Duck River: The Duck River is wholly in Tennessee and represents 
the farthest downstream significant tributary of the Tennessee River, 
joining it in the headwaters of Kentucky Reservoir. A single 
spectaclecase, representing a new drainage record, was found live in 
the lower Duck River, Hickman County, in 1999 (Hubbs 1999, p. 1; Powell 
2008, pers. comm.). Since then, at least one live and one fresh dead 
individual from the lower part of the river in Humphreys County have 
been documented (Ahlstedt et al. 2004, pp. 14-15; Schilling and 
Williams 2002, p. 410), and several relic specimens have been reported 
farther upstream (Hubbs 2008, pers. comm.; Powell 2008, pers. comm.). 
These records cover an approximately 20-mile (32-km) reach of river, 
with the live individual reported from the lower end of this reach. The 
spectaclecase is considered extremely rare in the Duck River, and its 
status is unknown.

Lower Mississippi River System

    The spectaclecase was apparently never widely distributed in the 
lower Mississippi River system. Records from only two streams are 
known, both from Arkansas.
    Mulberry River: The Mulberry River is a tributary of the Arkansas 
River in northwestern Arkansas. Other than the Ouachita River records, 
the only other record of the spectaclecase in the lower Mississippi 
River system is a single specimen found in the mid-1990s in the 
Mulberry River. There is some uncertainty regarding the validity of 
this record, as the collectors were not experienced malacologists, and 
no specimen or photograph is available to substantiate the record. This 
record is, however, accepted as valid (Harris et al. 2009, p. 67; 
Harris 2010, pers. comm.). The status of the spectaclecase in the 
Mulberry River is unknown.
    Ouachita River: The Ouachita River flows into lower Red River, a 
major western tributary of the lower Mississippi River, draining 
portions of Arkansas and Louisiana. This species was first reported in 
this portion of its range from the Ouachita River, southwestern 
Arkansas, in the early 1900s (Wheeler 1918, p. 121). Spectaclecase 
records in the Ouachita span a three-county reach of river. Only two 
live specimens were found in the mid-1990s, both in the lower portion 
of Ouachita County. A single relic shell (paired valves) was found in 
Montgomery County, at the upper end of its Ouachita River range in 
2000. The population is considered very small and declining (Harris et 
al. 2009, p. 67; Harris 2010, pers. comm.).

Summary of Extant Spectaclecase Populations

    The spectaclecase appears to be declining rangewide, with the 
exception of a few significant populations. Its occurrence in the St. 
Croix, Meramec, Gasconade, and Clinch Rivers represent the only 
sizable, sustainable, and reproducing populations remaining, although 
the Clinch River population appears to be in decline. The spectaclecase 
has been eliminated from three-fifths of the total number of streams 
from which it was historically known (20 streams currently compared to 
44 streams historically). This species has also been eliminated from 
long reaches of former habitat in thousands of miles of the Illinois, 
Ohio, Cumberland, and other rivers, and from long reaches of the 
Mississippi and Tennessee Rivers. In addition, the species is no longer 
known from the States of Ohio, Indiana, and Kansas. The

[[Page 14923]]

extirpation of this species from numerous streams and stream reaches 
within its historical range signifies that substantial population 
losses have occurred.

Sheepnose Historical Range and Distribution

    Historically, the sheepnose occurred in the Mississippi, Ohio, 
Cumberland, and Tennessee River systems and their tributaries, totaling 
at least 76 streams (including 1 canal) (Butler 2002a, pp. 6-7). Its 
distribution comprised portions of 14 States (Alabama, Illinois, 
Indiana, Iowa, Kentucky, Minnesota, Mississippi, Missouri, Ohio, 
Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin). 
Historical occurrences by stream system (with tributaries) include the 
following:
     Upper Mississippi River system (Mississippi River 
(Minnesota, St. Croix, Chippewa (Flambeau River), Wisconsin, Rock, 
Iowa, Des Moines, Illinois (Des Plaines, Kankakee, Fox, Mackinaw, 
Spoon, Sangamon (Salt Creek) Rivers; Quiver Creek; Illinois and 
Michigan Canal), Meramec (Bourbeuse, Big Rivers), Kaskaskia, Saline, 
Castor, Whitewater Rivers));
     Lower Missouri River system (Little Sioux, Little Blue, 
Gasconade (Osage Fork) Rivers);
     Ohio River system (Ohio River (Allegheny), Monongahela, 
Beaver, Duck Creek, Muskingum (Tuscarawas, Walhonding (Mohican River), 
Otter Fork Licking Rivers), Kanawha, Scioto, Little Miami, Licking, 
Kentucky, Salt, Green (Barren River), Wabash (Mississinewa, Eel, 
Tippecanoe, Vermillion, Embarras, White (East, West Forks White River) 
Rivers) Rivers);
     Cumberland River system (Cumberland River (Obey, Harpeth 
Rivers; Caney Fork));
     Tennessee River system (Tennessee River (Holston (North 
Fork Holston River), French Broad (Little Pigeon River), Little 
Tennessee, Clinch (North Fork Clinch, Powell Rivers), Hiwassee, Duck 
Rivers)); and
     Lower Mississippi River system (Hatchie, Yazoo (Big 
Sunflower River), Big Black Rivers).

Sheepnose Current Range and Distribution

    Extant populations of the sheepnose are known from 25 rivers in all 
14 States of historical occurrence. Current populations occur in the 
following systems (with tributaries):
     Upper Mississippi River system (Mississippi River 
(Chippewa (Flambeau River), Wisconsin, Rock, Kankakee, Meramec 
(Bourbeuse River) Rivers));
     Lower Missouri River system (Osage Fork Gasconade River);
     Ohio River system (Ohio River (Allegheny, Muskingum 
(Walhonding River), Kanawha, Licking, Kentucky, Tippecanoe, Eel, Green 
Rivers));
     Tennessee River system (Tennessee River (Holston, Clinch, 
Duck (Powell River) Rivers)); and
     Lower Mississippi River system (Big Sunflower River).
    The 25 extant sheepnose populations occur in the following 14 
States (with streams):
     Alabama (Tennessee River),
     Illinois (Mississippi, Kankakee, Ohio, Rock Rivers),
     Indiana (Ohio, Tippecanoe, Eel Rivers),
     Iowa (Mississippi River),
     Kentucky (Ohio, Licking, Kentucky, Green Rivers),
     Minnesota (Mississippi River),
     Mississippi (Big Sunflower River),
     Missouri (Mississippi, Meramec, Bourbeuse, Osage Fork 
Gasconade Rivers),
     Ohio (Ohio, Muskingum, Walhonding Rivers),
     Pennsylvania (Allegheny River),
     Tennessee (Tennessee, Holston, Clinch, Powell, Duck 
Rivers),
     Virginia (Clinch, Powell Rivers),
     West Virginia (Ohio, Kanawha Rivers), and
     Wisconsin (Mississippi, Chippewa, Flambeau, Wisconsin 
Rivers).
    The sheepnose was last observed from over two dozen streams decades 
ago (for example, Minnesota, Rock, Iowa, Illinois, Des Plaines, Fox, 
Mackinaw, Spoon, Castor, Little Sioux, Little Blue, Monongahela, 
Beaver, Scioto, Little Miami, Salt, Mississenewa, Vermilion, Embarras, 
White, Obey, Harpeth, North Fork Holston, French Broad, North Fork 
Clinch Rivers; Caney Fork). According to Parmalee and Bogan (1998, p. 
177) and Neves (1991, pp. 280-281), the sheepnose has been extirpated 
throughout much of its former range or reduced to isolated populations. 
The only records known from some streams are archeological specimens 
(for example, Little Pigeon, Big Black, Yazoo, Saline Rivers).

Sheepnose Population Estimates and Status

    The sheepnose has been eliminated from two-thirds of the total 
number of streams from which it was historically known (25 streams 
currently occupied compared to 77 streams historically) (Table 2). This 
species has also been eliminated from long reaches of former habitat 
including thousands of miles of the Mississippi, Wisconsin, Illinois, 
Ohio, Cumberland, and Tennessee Rivers and dozens of other streams and 
stream reaches.
    Based on the population designation criteria (see Species 
Distribution section, above), of the 25 sheepnose populations that are 
considered extant, 9 are thought to be stable and 8 are considered 
declining (Table 2). Six other populations (Walhonding, Rock, 
Gasconade, Muskingum, Osage Fork, and Duck Rivers) are considered 
extant, but the status of these populations is unknown.

                                Table 2--Sheepnose Status at Historical Locations
----------------------------------------------------------------------------------------------------------------
                                                                           Date of last live
          River Basin                  Stream          Current  status       or fresh dead          Comments
                                                                              observation
----------------------------------------------------------------------------------------------------------------
Upper Mississippi River........  Mississippi River.  Declining..........  2010.
                                 Minnesota River...  Extirpated.........  ~1944.               .................
                                 St. Croix River...  Extirpated.........  1988.                .................
                                 Chippewa/Flambeau   Stable.............  2008.                .................
                                  River.
                                 Wisconsin River...  Declining..........  2007.                .................
                                 Rock River........  Unknown............  2007                 Represented by
                                                                                                single specimen
                                                                                                presumably near
                                                                                                extirpation.
                                 Iowa River........  Extirpated.........  1985                 Relic shell
                                                                                                collected in
                                                                                                2011.
                                 Des Moines River..  Extirpated.........  ~1915.               .................
                                 Illinois River....  Extirpated.........  1940                 Relic shell
                                                                                                collected in
                                                                                                1999.
                                 Des Plaines River.  Extirpated.........  ~1970.               .................
                                 Kankakee River....  Stable.............  2007.                .................

[[Page 14924]]

 
                                 Fox River.........  Extirpated.........  ~1913.               .................
                                 Mackinaw River....  Extirpated.........  ~1970.               .................
                                 Spoon River.......  Extirpated.........  1929.                .................
                                 Sangamon River....  Extirpated.........  ~1919                Relic shell
                                                                                                collected in
                                                                                                1989.
                                 Salt Creek........  Extirpated.........  Unknown              Relic shell
                                                                                                collected in
                                                                                                2007.
                                 Quiver Creek......  Extirpated.........  1881.                .................
                                 Illinois and        Extirpated.........  ?                    .................
                                  Michigan (I and
                                  M) Canal.
                                 Meramec River.....  Stable.............  2011.                .................
                                 Bourbeuse River...  Declining..........  2006.                .................
                                 Big River.........  Extirpated.........  1978.                .................
                                 Kaskaskia River...  Extirpated.........  1970.                .................
                                 Saline River......  Extirpated.........  ?                    .................
                                 Castor River......  Extirpated.........  ~1965.               .................
                                 Whitewater River..  Extirpated.........  1970s.               .................
Lower Missouri River...........  Little Sioux River  Extirpated.........  1916.                .................
                                 Little Blue River.  Extirpated.........  ~1915.               .................
                                 Gasconade River...  Unknown............  ~1965.               .................
                                 Osage Fork          Unknown............  1999                 Represented by
                                  Gasconade River.                                              single specimen,
                                                                                                presumably near
                                                                                                extirpation.
Ohio River.....................  Ohio River........  Stable.............  2007.                .................
                                 Allegheny River...  Improving..........  2008.                .................
                                 Monongahela River.  Extirpated.........  ~1897.               .................
                                 Beaver River......  Extirpated.........  ~1910.               .................
                                 Duck Creek........  Extirpated.........  1930.                .................
                                 Muskingum River...  Unknown............  1993.                .................
                                 Tuscarawas River..  Extirpated.........  Unknown              Relic shell
                                                                                                collected in
                                                                                                1998.
                                 Walhonding River..  Unknown............  1993.                .................
                                 Mohican River.....  Extirpated.........  1977.                .................
                                 Otter Fork Licking  Extirpated.........  1973.                .................
                                  River.
                                 Kanawha River.....  Stable.............  2005.                .................
                                 Scioto River......  Extirpated.........  1963.                .................
                                 Little Miami River  Extirpated.........  ~1953.               .................
                                 Licking River.....  Declining..........  2007.                .................
                                 Kentucky River....  Declining..........  1996.                .................
                                 Salt River........  Extirpated.........  ~1900.               .................
                                 Green River.......  Improving..........  2007.                .................
                                 Barren River......  Extirpated.........  Unknown              Relic shell
                                                                                                collected in
                                                                                                1993.
                                 Wabash River......  Extirpated.........  1988.                .................
                                 Mississinewa River  Extirpated.........  1899.                .................
                                 Eel River.........  Declining..........  1997.                .................
                                 Tippecanoe River..  Stable.............  2009.                .................
                                 Vermillion River..  Extirpated.........  Unknown.             .................
                                 Embarras River....  Extirpated.........  1953.                .................
                                 White River.......  Extirpated.........  1913.                .................
                                 East White River..  Extirpated.........  1969.                .................
                                 West Fork White     Extirpated.........  1908                 Relic shell
                                  River.                                                        collected in
                                                                                                2000.
Cumberland River...............  Cumberland River..  Extirpated.........  1987.                .................
                                 Obey River........  Extirpated.........  1939.                .................
                                 Harpeth River.....  Extirpated.........  ?                    .................
                                 Caney Fork River..  Extirpated.........  Unknown              Relic shell
                                                                                                collected in
                                                                                                1990.
Tennessee River................  Tennessee River...  Stable.............  2008.                .................
                                 Holston River.....  Declining..........  2007.                .................
                                 North Fork Holston  Extirpated.........  1913.                .................
                                  River.
                                 French Broad River  Extirpated.........  1914.                .................
                                 Little Pigeon       Extirpated.........  Unknown.             .................
                                  River.
                                 Little Tennessee    Extirpated.........  Unknown              Relic shell
                                  River.                                                        collected in
                                                                                                1971.
                                 Clinch River......  Stable.............  2006.                .................
                                 North Fork Clinch   Extirpated.........  ~1921.               .................
                                  River.
                                 Powell River......  Stable.............  2004.                .................
                                 Hiwassee..........  Extirpated.........  Unknown              Relic shell
                                                                                                collected in
                                                                                                1975.
                                 Duck River........  Unknown............  2003                 Record
                                                                                                represented by
                                                                                                single specimen.
Lower Mississippi River........  Hatchie River.....  Extirpated.........  1983.                .................
                                 Yazoo River.......  Extirpated.........  Unknown.             .................
                                 Big Sunflower       Declining..........  2000.                .................
                                  River.
                                 Big Black River...  Extirpated.........  Unknown.             .................
----------------------------------------------------------------------------------------------------------------


[[Page 14925]]

    Historically, the sheepnose was fairly widespread in many 
Mississippi River system streams, although rarely common. 
Archaeological evidence on relative abundance indicates that it has 
been an uncommon or even rare species in many streams for centuries 
(Morrison 1942, p. 357; Patch 1976, pp. 44-52; Parmalee et al. 1980, p. 
101; Parmalee et al. 1982, p. 82; Parmalee and Bogan 1986, pp. 28, 30; 
Parmalee and Hughes 1994, pp. 25-26), and relatively common in only a 
few (Bogan 1990, p. 135).
    Museum collections of this species are almost always few in number 
(Cummings 2010, pers. comm.), with the exception of the 1960s 
collections from the Clinch and Powell Rivers, Tennessee and Virginia. 
Moderate numbers of individuals were also commonly recorded 
historically from the upper Muskingum River system in Ohio and the 
lower Wabash River in Indiana and Ohio, based on museum lots. Williams 
and Schuster (1989, p. 21) reported the species as being not common in 
the Ohio River, while Cummings and Mayer (1992, p. 50) considered it 
rare throughout its range. The American Malacological Union considers 
the sheepnose to be threatened (Williams et al. 1993, p. 13).
    Some known populations of the sheepnose are represented by the 
collection of a single specimen. Other populations have seen a dramatic 
range decline (for example, reduced from several hundred river miles to 
a single bed of a river system) or we have limited recent information 
on population status. The following summaries focus primarily on those 
populations for which we have sufficient information to make status and 
trend determinations, and less on those populations that are nearly 
extirpated, have no recruitment, or are of unknown status.

Upper Mississippi River System

    Judging from the archeological record, the sheepnose may have been 
common at some sites on the Mississippi River (Bogan 1990, p. 135) but 
over the past century it has become a rare species throughout the 
mainstem (Grier 1922, pp. 13-31; van der Schalie and van der Schalie 
1950, pp. 454-457). Robust populations may have been found in some 
tributary rivers. The sheepnose has been extirpated from seven 
Mississippi River tributaries (Minnesota, Iowa, Des Moines, Kaskaskia, 
Saline, Castor, and Whitewater Rivers) and all but one Illinois River 
tributary (the Kankakee River). Today, the sheepnose is extant (though 
in low numbers) in ten mainstem pools, and six tributary rivers of the 
Upper Mississippi River System.
    Mississippi River mainstem: Sheepnose populations in the mainstem 
of the Upper Mississippi River are declining. Despite the discovery of 
a juvenile in Mississippi River Pool (MRP) 7 in 2001, recruitment is 
limited at best. The mainstem population comprises a few old 
individuals spread across a very large geographic range (MRP 4 through 
MRP 24, a distance of more than 530 river miles (850 river km)) (Thiel 
1981, p. 10; Havlik and Marking 1981, p. 32; Whitney et al. 1996, p. 
17; Helms and Associates, Ecological Specialists, Inc. 2008, p. 16). 
The status of this species in the Mississippi River is highly 
vulnerable (Butler 2002a, p. 7).
    Pools with extant populations include MRP 4 (2008), MRP 5 (2008), 
MRP 7 (2001), MRP 11 (2007), MRP 14 (2006-07), MRP 15 (2005-06), MRP 16 
(2003), MRP 17 (2010), MRP 20 (1992), and MRP 24 (1999). The 2001 MRP 7 
record was for a live juvenile 1.3 inches (3.3 cm) long and estimated 
to be 3 years old (Davis 2008, pers. comm.).
    St. Croix River: The St. Croix River population is isolated and 
composed of old individuals with little to no recruitment (Heath 2010b, 
pers. comm.). Currently, the population is thought to be restricted to 
the lowermost mainstem below RM 1 in Washington County, Minnesota, and 
Pierce County, Wisconsin (Heath 2010b, pers. comm.). Three live 
individuals were collected in 1988, during a mussel relocation project 
for the U.S. Highway 10 bridge immediately upstream of the confluence 
with the Mississippi River (Heath 1989, p. 16). Hornbach (2001, p. 218) 
analyzed mussel collections throughout the St. Croix River and found 
that the sheepnose was absent in 15 of the 16 river reaches he sampled, 
only noting the 1988 occurrence. One historical occurrence is known 
from the vicinity of RM 53 in 1930; however, this is the only known 
record upstream of RM 1 (Heath 2010b, pers. comm.). Because there have 
been no recent collections in the St. Croix River since 1988, this 
population is most likely extirpated.
    Chippewa/Flambeau River: The sheepnose population in the Chippewa 
River is extant in much of the river system including the lower end of 
its tributary, the Flambeau River. This population is stable with 
documented recruitment (Butler 2002a, p. 8). Balding and Balding (1996, 
p. 5) reported 50 live specimens sampled from 1989 through 1994, but 
more recent collections have expanded sites of occurrence to 20 of 67 
sites in the middle and upper portions of the Chippewa River, with a 
relative abundance of 0.8 percent (Balding 2001, pers. comm.). Balding 
(1992, p. 166) found 12 live specimens and 31 dead shells from 5 of 37 
sites in the lower river. Additional survey work extended the number of 
sites where it was found live to 10 of 45 (Balding 2001, pers. comm.). 
The Chippewa River sheepnose population is considered one of the best 
known extant populations. The Flambeau River supports a small sheepnose 
population below its lowest dam and near its confluence with the 
Chippewa River (lower 8 miles (13 km) of river), and is most likely 
dependent on the source population in the Chippewa River.
    Wisconsin River: The sheepnose is declining in the Wisconsin River. 
Historical records for the sheepnose are available throughout the lower 
335 miles (539 km) of the 420-mile (676-km) Wisconsin River (Heath 
2010c, pers. comm.). In July 2002, researchers found 20 live specimens 
in a dense mussel bed near Port Andrew (Seitman 2011, pers. comm.). 
Currently, the sheepnose is primarily confined to RM 133.7 downstream 
(a reduction of over 201 river miles (232 km)). The sheepnose 
population is probably recruiting in the river, primarily in the lower 
section (below RM 82) (Heath 2010c, pers. comm.). It is unknown if the 
middle river population, from RM 93 to 133.7, is recruiting because 
only three living individuals have been found in recent years (Heath 
2010c, pers. comm.).
    Rock River: The Rock River population is represented by a single 
sheepnose specimen and is near extirpation. This individual was located 
in 2007 south of Como, Illinois (Tiemann 2011, pers. comm.; Cummings 
2010a, pers. comm.). Although there have been several relict shells 
found in the Rock River since 1990, the 2007 collection is the only 
known live collection in the past 50 years.
    Kankakee River: The sheepnose once occurred along the lower two-
thirds of the Kankakee River, an Upper Illinois River tributary, in 
Indiana and Illinois (Wilson and Clark 1912, p. 47; Lewis and Brice 
1980, p. 4). The sheepnose has been extirpated from the channelized 
portion of the Kankakee in Indiana but persists in the Illinois portion 
of the river where it appears stable, with evidence of recent 
recruitment (Butler 2002a, p. 9). Records since 1986 identify the 
sheepnose in the Kankakee River from the Iroquois River confluence 
downstream approximately 30 river miles (48 km) (Cummings 2010b, pers. 
comm.; Helms and Associates 2005, p. 3). A mussel relocation effort for 
a pipeline crossing in the Kankakee River in July 2002

[[Page 14926]]

found 11 sheepnose individuals, representing 0.32 percent of the total 
mussels relocated (Helms 2004, p. D-1). Subsequent monitoring of the 
site in 2004 and 2007 located four new individuals. One individual 
collected in 2004 measured 1.6 inches (40 mm) and was estimated to be a 
juvenile of 3 years of age. No sheepnose were found in a 2011 search of 
this area (Roe 2011, pers. comm.).
    Meramec River: The Meramec River flows into the Mississippi River 
downstream of St. Louis and drains east-central Missouri. The Meramec 
sheepnose population is stable and recruiting, and represents one of 
the best rangewide (Butler 2002a, p. 9). Two studies (Buchanan 1980, p. 
4; Roberts and Bruenderman 2000, p. 20) extensively surveyed the mussel 
fauna of the Meramec River. The most notable difference in the results 
of these studies was the reduced range in which sheepnose were found. 
Buchanan (1980, p. 34) found live or fresh dead individuals from RM 4.5 
to 145.7 (141.2 river miles (227.2 km)), whereas Roberts and 
Bruenderman (2000, p. 20) found live or fresh dead individuals from RM 
25.6 to 91.3 (65.7 river miles (105.7 km)). The trend data from the 
late 1970s to 1997 indicate that the sheepnose declined 75.5 river 
miles (121.5 km) in total range within the Meramec River. The extent of 
the population in the lower end appears to be shrinking upriver (Butler 
2002a, p. 10).
    In 2002, a site associated with a railroad crossing in St. Louis 
County at RM 28 yielded 43 live specimens over 3 days of sampling, 
including at least one gravid female (Roberts 2008a, pers. comm.). 
Collectively, these data reinforce the level of importance of the 
Meramec population for the sheepnose rangewide. Although the existing 
population has been described as stable and recruitment has been 
documented in the system (Butler 2002a, pp. 11-12), the population has 
shrunk by half of its former geographic range over the past 30 years.
    Bourbeuse River: The Bourbeuse River sheepnose population is 
distributed in the downstream 90 river miles (145 km) of the river 
(Buchanan 1980, p. 34), but is considered rare. Although recruitment 
has been documented in the Bourbeuse River, the sheepnose population is 
considered declining (Roberts and Bruenderman 2000, p. 130; Roberts 
2008b, pers. comm.). In the late 1970s, Buchanan (1980, p. 10) found 
the sheepnose to represent 0.1 percent of the Bourbeuse River mussel 
fauna, with 10 live specimens sampled from 7 sites. Based on data 
collected by Buchanan (1980, p. 34) and additional survey work in 1980, 
live or fresh-dead individuals were found in the Bourbeuse from RM 6.5 
to 90.0. Data from a resurvey of the Bourbeuse River collected in 1997 
yielded nine live sheepnose from four sites (Roberts and Bruenderman 
2000, p. 39), and fresh dead shells were located at an additional site. 
Sheepnose relative abundance was 0.4 percent. Live or fresh dead 
sheepnose were found between RM 1.4 to 66.3. This comparison indicates 
a decrease in the number of extant sites (7 to 4) and a range 
contraction of 18 river miles (29 km). The sheepnose in the Meramec and 
Bourbeuse Rivers represents a population cluster.

Lower Missouri River System

    Osage Fork Gasconade River: The Lower Missouri River system 
population is represented by a single sheepnose specimen and is near 
extirpation. This individual was located in 1999 at RM 21.2 in the 
Osage Fork, a tributary to the Gasconade River (Bruenderman et al. 
2001, p. 14). It is the only known record for sheepnose in the 
Gasconade River drainage for more than 25 years.

Ohio River System

    Historically, the sheepnose was documented from the entire length 
of the Ohio River (its type locality), and was first collected there in 
the early 1800s. Ohio River sampling of 664 river miles (1,068 km) 
along the northern border of Kentucky yielded 41 sheepnose (Williams 
1969, p. 58). Most of these (29) were found in the upper portions of 
the river (from RM 317 to 538), but the population extended downstream 
to RM 871. Relative abundance was 0.7 percent for the entire reach 
sampled. Currently, the mainstem Ohio River and 10 tributary streams 
have extant sheepnose populations.
    Ohio River mainstem: The sheepnose is generally distributed, but 
rare, in most mainstem pools of the Ohio River. The population appears 
to be more abundant in the lower section of the river with a smaller 
population in the upper Ohio River pools (Williams and Schuster 1989, 
p. 24; Zeto et al. 1987, p. 184). Long-term monitoring data from 1993 
to 2007 at RM 176 shows the sheepnose is usually collected each survey, 
recruitment is occurring, and the species comprises 1.0 percent of the 
mussels at the site (relative abundance) (Morrison 2008, pers. comm.). 
Live sheepnose have also been collected in recent years at RM 725 and 
RM 300 (Morrison 2008, pers. comm.). The population in the lower Ohio 
River mainstem is viable with documented recruitment, but the 
population overall continues to show signs of decline (Butler 2002a, p. 
12).
    Allegheny River: The Allegheny River drains northwestern 
Pennsylvania and western New York and joins the Monongahela River at 
Pittsburgh to form the Ohio River. Historical populations of sheepnose 
were located in the Allegheny in the sections of the river that are now 
Pools 5-8 (Urban pers. comm. 2011). In their surveys conducted from 
2005-07, Smith and Meyer (2010, p 558), found no sheepnose in Pools 4-
7. All of these populations have been extirpated leaving only the 
population in the middle Allegheny located above Pool 9 and below the 
Kinzua Dam (Urban 2011, pers. comm.). This remaining population has 
shown recent recruitment and is considered improving (Villella 2008, 
pers. comm.). Sampling efforts from 2006-08 at 63 sites over 78 miles 
(125 km) of river produced sheepnose at 18 sites. A total of 244 
individuals of 7 different age classes were collected (Villella 2008, 
pers. comm.) providing ample evidence of recent recruitment.
    Kanawha River: The Kanawha River is a major southern tributary of 
the Ohio River draining much of West Virginia and with headwaters in 
Virginia and North Carolina. The Kanawha River harbors a small, but 
recruiting and stable, population of sheepnose in Fayette County, West 
Virginia (Butler 2002a, p. 14). The Kanawha population appears to be 
limited to 5 river miles (8 km) immediately below Kanawha Falls 
(Clayton 2008b, pers. comm.). Sheepnose collections from this reach in 
1987 resulted in a density of 0.013 per sq. m (0.140 per sq. ft), and 
collections from 2005 found a density of 0.016 per sq. m (0.172 per sq. 
ft) (Clayton 2008b, pers. comm.).
    Licking River: The sheepnose is known from the lower half of the 
Licking River, a southern tributary of the Ohio River in northeastern 
Kentucky. Currently, the species is known from roughly five sites in 
the middle Licking River (McGregor 2008, pers. comm.). There is no 
documented evidence of recent recruitment, and, therefore, the 
sustainability of the population is unknown. It is possible this 
population represents a population cluster with the Ohio River.
    Green River: The Green River is a lower Ohio River tributary in 
west-central Kentucky. Currently, a recruiting and improving population 
remains over an approximately 25 river mile (40 km) reach in the upper 
Green River from the vicinity of Mammoth Cave National Park upstream 
into Hart County (Butler 2002a, p. 15). An investigation of

[[Page 14927]]

muskrat middens from 2002 and 2003 revealed 42 sheepnose shells, with 
39 of the 42 between 1.2 and 2.2 inches (3.0 and 5.6 cm) in length and 
described as juveniles (Layzer 2008b, pers. comm.). Sampling over the 
past several years (2005-07) has documented a number of beds 
experiencing recruitment (McGregor 2008, pers. comm.).
    Tippecanoe River: The Tippecanoe River drains the central portion 
of northern Indiana in the upper Wabash River system. This population 
of sheepnose is considered stable with relatively recent recruitment 
(Butler 2002a, p. 17). Survey work between 1987 and 1995 documented 
sheepnose at 14 sites throughout the river and extended the known range 
of the species upstream into Marshall County (Butler 2002a, p. 17). The 
sheepnose is now known from 45 miles (72 km) of the Tippecanoe River 
(Ecological Specialists, Inc. 1993, pp. 80-81; Cummings and Berlocher 
1990, pp. 84, 98; Cummings 2008b, pers. comm.; Fisher 2008, pers. 
comm.).
    Kentucky, Eel, Muskingum, and Walhonding Rivers: In addition to the 
aforementioned populations, sheepnose in the Ohio River system are 
known from the Kentucky and Eel Rivers, which are each represented by 
two or fewer specimens collected in the past 25 years. A population 
cluster in two additional rivers, the Muskingum River and its 
tributary, the Walhonding River, have unknown populations. Although 
Watters and Dunn (1995, p. 240) documented recruitment in the lower 
Muskingum River in the mid-1980s, the sheepnose population in the river 
is extremely small, and distribution has been reduced to only the lower 
portion of the river where six individuals were collected in 1992 
(Watters and Dunn 1995, pp. 253-254). Populations of the sheepnose in 
these three river systems are considered to be declining and may be 
nearing extirpation (Butler 2002a, pp. 15-16).

Cumberland River System

    Historical sheepnose records in the system are known from 
throughout the mainstem downstream of Cumberland Falls and three of its 
tributaries (Obey and Harpeth Rivers and Caney Fork). Wilson and Clark 
(1914, pp. 15-19, 57) reported the species to be generally uncommon 
from 14 mainstem sites from what is now Cumberland Reservoir, Kentucky, 
downstream to Stewart County, Tennessee, a distance of nearly 500 miles 
(805 km). The sheepnose was last documented in the Tennessee portion of 
the river during the early 1980s (Butler 2002a, p. 67).
    The only recent sheepnose record for the Cumberland River is from 
1987, at the extreme lower end of the river in Kentucky near its 
confluence with the Ohio River, below Barkley Dam (Butler 2002a, p. 
18). This population may be influenced by the lower Ohio River 
sheepnose population (Butler 2002a, p. 18) and represents a population 
cluster. Surveys conducted in 2007-09 in the Tennessee reach of the 
river found no sheepnose (Hubbs, 2010, pers. comm.), and so this 
population may be extirpated.

Tennessee River System

    The sheepnose was originally known from the Tennessee River and 10 
of its tributary streams. Historically, Ortmann (1925, p. 328) 
considered the sheepnose to occur ``sparingly'' in the lower Tennessee 
River, and to be ``rare'' in the upper part of the system (Ortmann 
1918, p. 545). Hundreds of miles of large river habitat on the 
Tennessee River mainstem have been converted under nine reservoirs, 
with additional dams constructed in tributaries historically harboring 
the sheepnose (for example, Clinch, Holston, Little Tennessee, Hiwassee 
Rivers) (Tennessee Valley Authority 1971, p. 5). Sheepnose populations 
currently persist in limited reaches of the Tennessee River mainstem 
and four tributaries.
    Tennessee River mainstem: The 53-mile (85-km) stretch of river in 
northwestern Alabama referred to as the Muscle Shoals historically 
harbored 69 species of mussels, making it the most diverse mussel fauna 
ever known (Garner and McGregor 2001, pp. 155-157). However, with the 
construction of three dams (Wilson in 1925, Wheeler in 1930, and 
Pickwick Landing in 1940) most of the historical habitat was inundated, 
leaving only small, flowing habitat remnants (Garner and McGregor 2001, 
p. 158).
    The species is found only occasionally in the lower Tennessee River 
below Pickwick Landing Dam in southwestern Tennessee. Scruggs (1960, p. 
11) recorded a relative abundance of 0.2 percent, while Yokley (1972, 
p. 64) considered it to be ``very rare'' in this reach (relative 
abundance of 0.1 percent). Yokley reported only two specimens that were 
each estimated to be 20 or more years old.
    The sheepnose persists in the tailwaters of Guntersville, Wilson, 
Pickwick Landing, and Kentucky Dams on the mainstem Tennessee River, 
where it is considered uncommon (Garner and McGregor 2001, p. 165; 
Gooch et al. 1979, p. 9). These populations are considered stable 
overall but with very limited recruitment (Garner and McGregor 2001, p. 
165; McGregor 2008, pers. comm.). The species has been found in low 
numbers over the past 80 years from relic habitat in the Wilson Dam 
tailwaters, a several-mile reach adjacent to and downstream from 
Florence, Alabama (Butler 2002a, pp. 20-21).
    Holston River: In July 2002, sampling in the Holston River produced 
live sheepnose at 16 of 20 sites sampled below the Cherokee Dam. This 
reach extended from Nance Ferry to Monday Island (RM 14.6), Jefferson 
and Knox Counties (Fraley 2008b, pers. comm.). A total of 206 specimens 
was found with an overall relative abundance of 18.2 percent among the 
18 species reported live from this reach. The collection comprised 
extremely old individuals with no recently recruited individuals being 
found. Although the population appeared significant in numbers, the 
lack of recruitment in this population is indicative of a remnant 
population on its way to extirpation (Butler 2002a, p. 19). In 2007, 
Tennessee Valley Authority biologists located sheepnose in the Holston 
River while conducting fish surveys; however, no additional mussel 
survey work has been completed in the area since 2002 (Baxter 2010, 
pers. comm.).
    Clinch River: The Clinch River in southwestern Virginia and 
northeastern Tennessee is one of the largest and most significant 
tributaries of the upper Tennessee River system. Based on archeological 
evidence, the sheepnose was ``extremely rare'' in the lower Clinch 
River (Parmalee and Bogan 1986, p. 28). As of 2002, the largest lots of 
museum material available for the sheepnose had been from the Clinch 
River and its tributary, the Powell River (Watters 2010a, pers. comm.). 
Individual Clinch River museum lots collected during 1963 to 1969 
include 36, 39, 70, and 82 fresh dead specimens. The sheepnose 
population in the Clinch River currently occurs over approximately 60 
river miles (96 km) from northern Scott County, Virginia, downstream 
into Hancock County, Tennessee, and is considered stable with recently 
documented recruitment (Eckert 2008b, pers. comm.). Survey work between 
1979 and 1994 (Ahlstedt and Tuberville 1997, p. 73) reported low 
densities of 0.009 to 0.018 individuals per sq. ft. (0.1 to 0.2 per sq. 
m). Sampling efforts in 2005 and 2006 reported densities from two sites 
(RM 223.6 and 213.2) in Scott County, Virginia, of 0.226 and 0.064 
individuals per sq. ft (0.021 and 0.006 per sq. m), respectively 
(Eckert 2008b, pers. comm.). Relative abundance for

[[Page 14928]]

sheepnose at these locations was 1.5 percent and 1.0 percent, 
respectively.
    Powell River: The largest sheepnose collection (OSUM) known 
rangewide was collected in the Powell River, the Clinch River's largest 
tributary, and included 6 live and 141 fresh dead specimens. Today, the 
sheepnose population in the Powell River is considered stable, and 
recruitment has been documented. In 1979, Ahlstedt (1991b, pp. 129-130) 
reported 45 live specimens from 17 of 78 sites (an average of 2.6 
individuals per site). Ahlstedt and Tuberville (1997, p. 96) conducted 
quantitative sampling in the Powell between 1979 and 1994, and found 
the sheepnose at densities of 0.107 and 0.861 per sq. ft (0.01 to 0.08 
per sq. m). Sampling efforts in 2004 reported densities from two sites 
in Lee County, Virginia (RM 120.3 and 117.3), of 0.129 and 0.183 
individuals per sq. ft (0.012 and 0.017 per sq. m), respectively 
(Eckert 2008b, pers. comm.). Relative abundance for sheepnose was 0.82 
percent and 0.99 percent, respectively.
    Duck River: The Duck River population is recently represented by 
the collection of a single, live, 10+-year-old animal in 2003 (Saylors 
2008, pers. comm.; Ahlstedt et al 2004, p. 24). The sheepnose was 
likely always rare in the Duck River (Ahlstedt et al 2004, p. 24) and, 
previous to 2003, the species was thought to be extirpated as the 
species had not been collected in the River for 100 years. The current 
status of the population is unknown.

Lower Mississippi River System

    The sheepnose was apparently never widely distributed in the lower 
Mississippi River system. The only verified records are for the Hatchie 
River in Tennessee and the Delta region in Mississippi. The only 
records for the Yazoo and Big Black Rivers are from archeological sites 
(Butler 2002a, p. 21). The sheepnose population in the Big Sunflower 
River, Mississippi, is the only one remaining in the lower Mississippi 
River system. Once abundant, judging from museum and archeological 
records, there is now only a small declining population in the Big 
Sunflower River (Jones 2008, pers. comm.). The population is believed 
to be limited to a 12- to 15-mile (19- to 24-km) reach upstream of 
Indianola in Sunflower County, Mississippi. Although no juvenile 
mussels have been found in recent sampling efforts, variably sized 
individuals indicate some, possibly very low, level of recruitment in 
the population (Jones 2008, pers. comm.).

Summary of Extant Sheepnose Populations

    The sheepnose has experienced a significant reduction in range, and 
many of the extant populations are disjunct, isolated, and appear to be 
declining. The extirpation of this species from more than 50 streams 
(more than 65 percent) within its historical range indicates that 
substantial population losses have occurred. In the majority of streams 
with extant populations, the sheepnose appears to be uncommon at best. 
Only in the Allegheny and Green Rivers is the species considered to be 
improving in population status. Several other extant populations are 
thought to exhibit some level of stability and have experienced 
relatively recent recruitment (Chippewa/Flambeau, Meramec, Ohio, 
Tippecanoe, Clinch, and Powell Rivers). Given the compilation of 
current distribution, abundance, and status trend information, the 
sheepnose appears to exhibit a high level of imperilment.

Summary of Comments and Recommendations

    In the proposed rule published on January 19, 2011 (76 FR 3392-
3420), we requested that all interested parties submit written comments 
on the proposal by March 21, 2011. We contacted appropriate State and 
Federal agencies, county governments, elected officials, scientific 
organizations, and other interested parties and invited them to 
comment. We also published notices inviting general public comment in 
12 newspapers throughout the range of the species. We did not receive 
any requests for a public hearing.
    During the comment period for the proposed rule, we received a 
total of 16 comment letters directly addressing the proposed listing of 
the sheepnose and spectaclecase with endangered status. Six State 
agencies, three Federal agencies, six groups, and four individuals 
submitted comments. Of those, 15 were comments in support of the 
listing, 2 were not in support of the listing, and 2 did not express a 
clear position. The State of Virginia provided additional records of 
both species, and Pennsylvania provided information about additional 
threats to the sheepnose. The State of Missouri provided additional 
information about both species and their threats. The States of Iowa, 
Pennsylvania, Missouri, Virginia, and Wisconsin expressed their support 
of the listings. The remainder of the States did not express a position 
on the actions. All substantive information provided during the comment 
period has either been incorporated directly into this final 
determination or addressed below. For readers' convenience, we have 
combined similar comments into single comments and responses.

Peer Review

    In accordance with our peer review policy published in the Federal 
Register on July 1, 1994 (59 FR 34270), we solicited expert opinion 
from eight knowledgeable individuals with scientific expertise on 
freshwater mollusks, applicable river basins, and conservation biology 
principles. The purpose of such review is to ensure that the 
designation is based on scientifically sound data, assumptions, and 
analyses, including input of appropriate experts and specialists.
    We received written responses from three peer reviewers. All peer 
reviewers stated that the proposal included a thorough and accurate 
review of the available scientific and commercial data on these 
mollusks and their habitats. One peer reviewer provided information on 
observed behavior of the spectaclecase. Two reviewers provided 
additional location information for the spectaclecase and the 
sheepnose. One reviewer provided information on additional or emerging 
threats to one or both species. Peer reviewer comments are addressed in 
the following summary and incorporated into the final rule as 
appropriate.

Peer Reviewer Comments

    (1) Comment: Peer reviewers provided updated information on 
spectaclecase and sheepnose populations throughout the ranges of these 
species.
    Our Response: The updates have been incorporated into this final 
rule. These changes made to the known populations have not changed our 
final determinations.
    (2) Comment: Peer reviewers agreed with the Service and commented 
that both species were valid species, the data provided was valid and 
adequate, and the threats presented were real to both species.
    Our Response: These comments support the Service's proposal.
    (3) Comment: One peer reviewer commented that the spectaclecase may 
be more active than stated in the proposal and cited a relocation study 
in the St. Croix River where spectaclecase were observed as the most 
active species among those relocated.
    Our Response: We have incorporated information into the Background 
section of this final rule. Movement of this species may deserve 
further investigation during recovery planning and implementation.

[[Page 14929]]

    (4) Comment: Peer reviewers commented that the Service provided 
sufficient evidence to show that both species are threatened by habitat 
destruction and curtailment. They further stated that both species 
depend on stable substrate within medium to large rivers and that 
rivers within their ranges have been modified by impoundment, 
channelization, and contamination. One reviewer stated that these 
threats may increase in the future with completion of restorations to 
the lock and dam system on the Ohio River and the planned navigation 
improvements on the Mississippi River associated with the authorized 
Navigation and Ecosystem Sustainability Program (NESP). The stability 
of habitat is further threatened by changes in local hydraulics due to 
instream construction and modification, and by the increased frequency 
of large-scale flooding (a result of climate change, destruction of 
riparian corridors, and decreased permeability within watersheds).
    Our Response: These comments support the Service's proposal. 
Further discussion regarding this topic is under Factor A: The Present 
or Threatened Destruction, Modification, or Curtailment of Their 
Habitat or Range and Factor E: Other Natural or Manmade Factors 
Affecting Its Continued Existence of this final rule.
    (5) Comment: Peer reviewers agreed with the Service and commented 
that both species are not overutilized for commercial, recreational, 
scientific, or educational purposes.
    Our Response: These comments support the Service's proposal. 
Further discussion regarding this topic is under Factor B: 
Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes of this final rule.
    (6) Comment: Peer reviewers commented that little is known about 
the effects of disease or predation on these species and that, while 
these factors do not seem to currently be an imminent threat, small and 
disjunct populations are more vulnerable to these factors.
    Our Response: These comments support the Service's proposal. 
Further discussion regarding disease and predation is under Factor C: 
Disease or Predation of this final rule. Disease and predation may be 
further investigated during recovery planning and implementation for 
both species.
    (7) Comment: One peer reviewer commented that chemical 
contamination from both point and nonpoint discharges will continue as 
significant threats to freshwater mussels due to their sedentary life 
form, which limits their ability to avoid exposure.
    Our Response: These comments support the Service's proposal. The 
potential effects of contaminants on freshwater mussels are further 
discussed under Factor A: The Present or Threatened Destruction, 
Modification, or Curtailment of Their Habitat or Range.
    (8) Comment: One peer reviewer commented that the distribution of 
mussels in river systems appears to be greatly dependent on complex 
hydraulic characteristics and that the increased frequency of extreme 
events in the wake of global climate change could be major contributors 
to future habitat availability for these mussel species.
    Our Response: These comments support the Service's proposal. The 
potential effects of climate change on freshwater mussels are further 
discussed under Factor E: Other Natural or Manmade Factors Affecting 
Its Continued Existence of this final rule. The effects of climate 
change may be further investigated during recovery planning and 
implementation for both species.
    (9) Comment: Peer reviewers commented that existing regulatory 
mechanisms do not prevent the destruction or modification of habitat 
for these species and that these species continue to decline despite 
existing regulations. The peer reviewer stated that endangered status 
would provide additional protection for remaining populations.
    Our Response: These comments support the Service's proposal. 
Existing regulations are discussed under Factor D: The Inadequacy of 
Existing Regulatory Mechanisms of this final rule.
    (10) Comment: Peer reviewers commented that the effects of zebra 
mussels are well documented in the rule and the effects of other 
invasive species will add to the stresses these species face; the 
effects of invasive species on both the spectaclecase and sheepnose 
need further study.
    Our Response: These comments support the Service's proposal. The 
potential effects of invasive species on freshwater mussels are further 
discussed under Factor E: Other Natural or Manmade Factors Affecting 
Its Continued Existence of this final rule. The effects of invasive 
species may be further investigated during recovery planning and 
implementation for both species.
    (11) Comment: One peer reviewer commented that, in order to 
effectively protect these mussels, further study is needed to determine 
how temperature affects both species.
    Our Response: These comments support the Service's proposal. The 
potential effects of temperature on freshwater mussels are further 
discussed under Factor E: Other Natural or Manmade Factors Affecting 
Its Continued Existence of this final rule. The effects of temperature 
on both species may be further investigated during recovery planning 
and implementation.
    (12) Comment: One peer reviewer commented that, in order to 
effectively protect these mussels, further study is needed on the 
genetics of both species.
    Our Response: These comments support the Service's proposal. The 
genetics of both species are discussed under Factor E: Other Natural or 
Manmade Factors Affecting Its Continued Existence of this final rule. 
The effects of invasive species may be further investigated during 
recovery planning and implementation for both species.
    (13) Comment: One peer reviewer commented that a recent genetic 
study of the sheepnose indicates that extant populations appear to be 
genetically isolated from each other and that populations should be 
managed as independent entities for purposes of captive rearing and 
propagation unless there is additional evidence to do otherwise. This 
reviewer provided updated information of collections of the sheepnose 
mussel from several locations.
    Our Response: We appreciate the submission of this updated 
information. These comments have been added to the Background section 
of this final rule.
    (14) Comment: One peer reviewer recommended that large rock and 
rock structures be considered for inclusion as possible critical 
habitat for the spectaclecase mussel.
    Our Response: We appreciate the comments. This rule only covers the 
listing of the two mussel species. We determined that, although the 
designation of critical habitat is prudent, it is not determinable at 
this time. Therefore, we did not propose critical habitat in the 
proposed listing rule and no critical habitat is designated with this 
final listing rule. We will use information provided to us in 
developing a future critical habitat proposal. Once a proposal is 
published, we will seek additional public comment on our proposed 
critical habitat designation.

State Comments

    (15) Comment: The Pennsylvania Fish and Boat Commission, Wisconsin

[[Page 14930]]

Department of Natural Resources Bureau of Fisheries and Habitat and 
Endangered Resources, Missouri Department of Conservation, Iowa 
Department of Natural Resources, and Virginia Department of Game and 
Inland Fisheries provided comments stating that they support the 
proposal to list both species.
    Our Response: We are grateful for support of the States and 
recognize that State partnerships are essential for the conservation of 
these species.
    (16) Comment: The Pennsylvania Fish and Boat Commission, Wisconsin 
Department of Natural Resources Bureau of Fisheries and Habitat and 
Endangered Resources, Missouri Department of Conservation, and Virginia 
Department of Game and Inland Fisheries provided updated historical and 
current information on populations of one or both species in their 
States.
    Our Response: We appreciate the submission of the updated 
information. The updates have been incorporated into this final rule.
    (17) Comment: The Pennsylvania Fish and Boat Commission stated that 
the record of occurrence for the sheepnose in Hemlock Creek is not 
accurate. The occurrence record is from the Allegheny River in Venango 
County, Pennsylvania, near the mouth of Hemlock Creek. Further, the 
reference to Duck Creek in the Beaver River drainage should be 
clarified. Duck Creek is a tributary to the Mahoning River, which flows 
through eastern Ohio and into Pennsylvania. The Mahoning River joins 
the Shenango River at New Castle, Pennsylvania, to form the Beaver 
River. The Beaver River mainstem, which flows to the Ohio River, is 
contained entirely within the borders of Pennsylvania.
    Our Response: We appreciate the submission of the updated 
information. The updates have been incorporated into this final rule.
    (18) Comment: The Virginia Department of Game and Inland Fisheries 
was not aware of historical records of the spectaclecase in the Powell 
River in Virginia.
    Our Response: We are aware of two spectaclecase records in the 
Powell River in Tennessee from 1978 and 1999 (Ahlstedt 2001, pers. 
comm.) but agree that no records are known from the Virginia portion of 
the river; therefore, we have kept the Powell River as a historical 
location for spectaclecase in this final rule.
    (19) Comment: The Pennsylvania Fish and Boat Commission and the 
Missouri Department of Natural Resources provided updated information 
on State protection of these species in their respective States. The 
spectaclecase is considered to be a Species of Conservation Concern in 
Missouri, and is therefore afforded certain protections under 
Missouri's Wildlife Code (3 CSR 10-9, 110(1) (B)); the spectaclecase is 
not currently listed as endangered in the State of Missouri (3 CSR 10-
4, `111). The sheepnose was State-listed as threatened in Pennsylvania 
on July 11, 2009.
    Our Response: The Service appreciates the clarifications. We have 
corrected information under Factor D; The Inadequacy of Existing 
Regulatory Mechanisms in this final rule.
    (20) Comment: The Pennsylvania Fish and Boat Commission provided 
information on threats to the sheepnose from a flood control project 
that could subject the species to changes in the thermal or flow 
regimes. Current flow management from the Allegheny Reservoir should be 
maintained or improved, where possible, in order to sustain downstream 
mussel populations. Flow management from the Kinzua Dam could be used 
to maintain mussel populations if faced with future impacts from 
climate change.
    Our Response: We appreciate the submission of information on the 
potential threats of flood control and water management as it supports 
our assumption that these activities could threaten multiple 
populations of the sheepnose. The information has been incorporated 
into this final rule under Factor A: The Present or Threatened 
Destruction, Modification, or Curtailment of Their Habitat or Range.
    (21) Comment: The Pennsylvania Fish and Boat Commission commented 
on the importance of restoring host fish passage between navigation 
pools in the Allegheny and Ohio Rivers in order to promote the 
recolonization of the sheepnose via its host fish. They noted that 
current plans to restore fish passage around upper Ohio River locks and 
dams are at risk and a recent study described the implementation of 
fish passage as infeasible.
    Our Response: We appreciate the comments. The issue of the fish 
passage will be investigated further under recovery planning and 
implementation for both species.
    (22) Comment: The Missouri Department of Conservation provided 
information on threats to both species from heavy metal sedimentation 
in the Big River, Missouri.
    Our Response: We appreciate the submission of information on the 
potential threats of heavy metal sedimentation as it supports our 
assumption that this activity could threaten multiple populations of 
the sheepnose and spectaclecase. The information has been incorporated 
into this final rule under Factor A: The Present or Threatened 
Destruction, Modification, or Curtailment of Their Habitat or Range.
    (23) Comment: The Missouri Department of Conservation provided 
information on threats to the spectaclecase from operation of 
hydropower facilities in the Salt River, Missouri.
    Our Response: Although there are historical records of 
spectaclecase in the Salt River, we are unaware of any recent extant 
records of spectaclecase in the Salt River. The potential effects of 
the hydropower dam would be considered in recovery planning and 
implementation if any populations are discovered in the future. The 
information has been incorporated into this final rule under Factor A: 
The Present or Threatened Destruction, Modification, or Curtailment of 
Their Habitat or Range.
    (24) Comment: The Pennsylvania Fish and Boat Commission provided 
information on threats to the sheepnose from natural gas extraction 
from the Marcellus Shale formation. Current increases in natural gas 
extraction related to Marcellus Shale present a number of potential 
threats to the sheepnose, including the removal of large volumes of 
surface and groundwater for hydrofracking, spills of untreated fracking 
flowback water, and development of infrastructure associated with 
natural gas extraction.
    Our Response: We appreciate the submission of information on the 
potential threats of natural gas extraction as it supports our 
assumption that this activity could threaten multiple populations of 
the sheepnose and spectaclecase. The information has been incorporated 
into this final rule under Factor A: The Present or Threatened 
Destruction, Modification, or Curtailment of Their Habitat or Range and 
Factor E: Other Natural or Manmade Factors Affecting Their Continued 
Existence.
    (25) Comment: The Pennsylvania Fish and Boat Commission and the 
Pennsylvania Biological Survey provided information on golden algae 
(Prymnesium parvum) as a threat to sheepnose populations in areas where 
water is withdrawn for shale gas drilling. Shale gas drilling has the 
potential to impact at least one of the best remaining sheepnose 
populations.
    Our Response: We appreciate the submission of information on the 
potential threats of golden algae as it supports our assumption that 
this activity could threaten multiple

[[Page 14931]]

populations of the sheepnose and spectaclecase. The information has 
been incorporated into this final rule under Factor E: Other Natural or 
Manmade Factors Affecting Their Continued Existence.
    (26) Comment: The Pennsylvania Fish and Boat Commission provided a 
comment regarding black carp (Mylopharyngodon piceus), a molluscivore 
(mussel-eater), as a potential threat to these species. Although the 
black carp is currently known from the Mississippi River and Illinois 
River drainages, there has been inadequate sampling in the Ohio River 
drainage and the potential for the species to move to the Allegheny 
River via the Ohio River is a real threat.
    Our Response: We appreciate the submission of information on the 
potential threats of black carp as it supports our assumption that this 
activity could threaten multiple populations of the sheepnose and 
spectaclecase. Information on the black carp as a threat to these 
species has been incorporated into this final rule under Factor E: 
Other Natural or Manmade Factors Affecting Their Continued Existence.
    (27) Comment: The Wisconsin Department of Natural Resources Bureau 
of Fisheries and Habitat and Endangered Resources provided a comment 
indicating the importance of determining the host fish of the 
spectaclecase and that, if the host fish is negatively impacted, the 
species is also negatively impacted.
    Our Response: Discussion on the role of the host fish was included 
in the proposed rule in the Life History section and under Factor A: 
The Present or Threatened Destruction, Modification, or Curtailment of 
Their Habitat or Range and Factor E: Other Natural or Manmade Factors 
Affecting Their Continued Existence. The issue of the host fish 
determination and conservation will be investigated further under 
recovery planning and implementation for the species.
    (28) Comment: The Virginia Department of Mines, Minerals and Energy 
comments did not support the proposed rule to list either species. They 
stated that, for the past 30 years, the Virginia Department of Mines, 
Minerals, and Energy has worked with the mining industry to regulate 
the mining industry in southwestern Virginia. The Surface Mining 
Control and Reclamation Act of 1977 has helped reduce impacts to land 
and water resources throughout the Clinch River and Powell River 
watersheds that harbor many species of freshwater mussels. Sheepnose 
populations are considered stable in the Clinch River; however, the 
statement regarding coal mining and ``coal-related toxins'' in the 
proposed rule attempts to relate declining populations with mining in 
Virginia. The proposal failed to include a 2007 Service study of the 
toxicity of Powell River mining effluent screenings and slurry on 
juvenile mussels. This study showed no effect on survival or growth of 
the tested mussels.
    Our Response: The 2007 study cited by the commenter was part of a 
3-year (2007-10) study that the Service conducted in conjunction with 
the U.S. Geological Survey (for example, Wang et al. 2007c). In 2007, 
Wang et al. (2007d, p. 1) reported that 100 percent of the coal slurry 
tested for a 48-hour exposure time resulted in a statistically 
significant reduced survival of juvenile rainbow mussels (Villosa 
iris). Slurry particles mixed with well-water were not acutely or 
chronically toxic to the juvenile mussels, indicating that the toxicity 
in this instance is related to contaminants in the slurry water (Wang 
et al. 2007d, p. 1). Further investigations by Kunz et al. (2010, p. 1) 
assessed the potential effects of coal-associated contaminants in 
sediment on wavy-rayed lamp-mussels (Lampsilis fasciola), rainbow 
mussels, and commonly tested amphipods and midges.
    Kunz et al. (2010, p. 1) studied sediment samples collected from 13 
sites with historically impacted mussel communities and coal mining or 
gas well activities and 5 reference sites with healthy mussel 
communities and no or limited coal mining activities in the Clinch and 
Powell River basins in Tennessee and Virginia. Mean survival or growth 
of one or more test organisms was reduced in 9 of 13 sediments from 
sites with active coal mining or gas well activities relative to the 
response of test organisms in 5 reference sites. A higher proportion of 
samples were designated as toxic to the mussels (71 percent) compared 
to amphipods (29 percent) or midge (29 percent) in sediment samples 
tested with all three species. Mussel growth or biomass decreased with 
increasing mean metal probable effect concentration (PEC)-quotient or 
with increasing concentrations of total polycyclic aromatic hydrocarbon 
compounds (PAHs), indicating juvenile mussels may be more sensitive to 
metals and PAHs than other test organisms, and the PEC threshold may 
need to be lowered to be protective of mussels (Kunz et al. 2010, p. 
1). Polycyclic aromatic hydrocarbon compounds have been found at 
relatively high levels in the upper portions of the Clinch and Powell 
Rivers in Virginia (Hampson et al. 2000, p. 20). Mussel growth also 
tended to decrease with increasing concentrations of major anions 
(sulfate and chloride), major cations (sodium and potassium), or 
conductivity in pore-water of sediments (Kunz et al. 2010), which was 
consistent with previous findings of reduced mussel survival in 
reconstituted waters with elevated concentrations of major anions and 
major cations (Wang et al. 2010, pp. 14-25).
    Despite considerable information on the effects of contaminants on 
fish and other aquatic species, there are few studies that allow us to 
confidently predict the effects of individual contaminants on the 
survival, reproduction, and behavior of freshwater mussels in general, 
and spectaclecase and sheepnose mussels and their hosts fish in 
particular, under the variety of contaminant concentrations and 
conditions that may be encountered. Information on the effects of 
cadmium, ammonia, potassium, and copper is sufficient to predict 
effects with knowledge of concentrations, but other contaminants, such 
as EDCs, boron, manganese, and others, have largely unstudied effects 
on mussels. In the absence of species-specific data, we assume that the 
spectaclecase and sheepnose may be more sensitive to contaminants than 
standard test organisms for toxicity testing, based in part on studies 
that have demonstrated greater sensitivity (for example, Keller and Zam 
1991; Jacobson et al. 1997; Cherry et al. 2002; Augspurger et al. 2003; 
Wang et al. 2007a, b; Bringolf et al. 2007a, b, c).
    We also demonstrated that established criteria or benchmarks 
currently in place to protect aquatic life may not be adequate to 
protect the spectaclecase and sheepnose mussels. Since the Virginia 
Department of Mines, Minerals, and Energy did not provide definitive 
information as to the relative safety of mined materials and chemicals 
on the spectaclecase and sheepnose, we will rely on the data we have 
compiled in this final rule to support our determination.
    (29) Comment: The Virginia Department of Mines, Minerals, and 
Energy commented that regulations and best management practices that 
are currently in place in Virginia emphasize improving water quality in 
areas impacted by mining and other activities. Areas in the Clinch 
River have improved such that there is emerging interest in 
reintroducing propagated mussels there. River ecosystems have shown 
signs of improved water quality and habitat since the sheepnose and 
spectaclecase mussels were identified as candidate species in 2004. 
They further

[[Page 14932]]

stated that a 5-year timeframe of investigation does not seem adequate 
when attempting to gauge the response of an organism to water quality 
improvements.
    Our Response: The Code of Virginia states that discharges of water 
from areas disturbed by surface mining activities shall be made in 
compliance with all applicable State and Federal water quality laws, 
standards, and regulations and with the effluent limitations for coal 
mining promulgated by the U.S. Environmental Protection Agency set 
forth in 40 CFR 434 (45.1-161.3 and 45.1-230 of the Code of Virginia 
available online at http://leg1.state.va.us/000/reg/TOC04025.HTM). 
However, as we have indicated in the Summary of Factors Affecting the 
Species section of this final rule, Federal and State water quality 
regulations are not adequate to protect the spectaclecase and sheepnose 
mussels. Best management practices for sediment and erosion control may 
be required by local ordinances for mining projects; however, 
compliance, monitoring, and enforcement of these recommendations are 
often poorly implemented. A myriad of pollutants, such as heavy metals, 
heavy sediment loads, and polycyclic aromatic hydrocarbon compounds, in 
mining wastewater discharge can be problematic to waterways when 
present in elevated levels.
    While recent improvements to water quality may have occurred in 
some areas, current population data for the spectaclecase continues to 
show little evidence of recent recruitment (Butler 2012, pers. comm.). 
The upper Clinch River has reproducing populations of spectaclecase; 
however, the overall population of spectaclecase in the Clinch River is 
declining. The Clinch River is one of the few locations where sheepnose 
populations are considered stable with evidence of recent recruitment 
(Butler 2012, pers. comm.), though the population densities are 
relatively low. Although the species' response to water quality 
improvements may not be completely evident over the last 5 years, 
throughout the recovery process for these species, we will monitor 
whether those recent water quality improvements will lead to improving 
sheepnose and spectaclecase populations.

Federal Agencies Comments

    (30) Comment: The Natural Resources Conservation Service of West 
Virginia provided comments stating that it would be unfortunate if both 
species were listed. They stated that several Federal programs, such as 
the Wildlife Habitat Incentives Program and the Environmental Quality 
Incentives Program, emphasize stream habitat restoration. Water quality 
and habitat improvement projects brought to fruition through these 
conservation practices may prevent the need to list these species.
    Our Response: Restoration programs such as those listed above are 
important conservation tools and may aid species recovery. Despite 
these programs, the Service has documented significant declines in the 
range and population size of spectaclecase and sheepnose and 
significant threats to these species (see Background and the Summary of 
Factors Affecting the Species section of this final rule). Based on our 
analysis of the best data available, we have no reason to believe that 
population trends for either species addressed in this final rule will 
improve, nor will the effects of current threats acting on the species 
be ameliorated in the foreseeable future. We recognize that 
partnerships are essential for the conservation of these species.
    (31) Comment: The Natural Resources Conservation Service of West 
Virginia provided comments encouraging agency partnerships with the 
Service to conserve both species.
    Our Response: The Service seeks partnerships with all interested 
parties to conserve these species. We encourage the Natural Resources 
Conservation Service to be an active participant in the recovery 
planning and implementation process for these species in West Virginia 
and in other States as well.
    (32) Comment: Under section 7 of the Act, Federal permitting 
agencies must determine if their projects may affect listed species. 
Will mussel survey standards be established to determine if mussels are 
in an area of a project? Also, are standards proposed in order for 
individuals to be qualified to survey for these species? Is there a 
level of impact that the Service would programmatically concur is not 
likely to adversely affect listed species?
    Our Response: Under section 7 of the Act, Federal action agencies 
will need to consult with us should their activities adversely affect 
the species. If a Federal agency wants to consult on a program that may 
affect these listed mussels, we will conduct a programmatic section 7 
consultation with that agency on that program. A determination of not 
likely to adversely affect needs to be made by the Federal agency and 
be supported by the appropriate documentation before we can provide 
concurrence. We will work with agencies to ensure that the best 
available data is used during consultation. Issues of standardizing 
survey protocols and surveyor qualifications may be further discussed 
during the recovery planning and implementation process for both 
species.

Public Comments

    (33) Comment: The Service received comments from three groups 
supporting the proposal to list both species. Additionally, the 
Pennsylvania Biological Survey and the Western Pennsylvania Conservancy 
supported the listing of the sheepnose but did not comment on the 
spectaclecase, since that species is not historically known from 
Pennsylvania.
    Our Response: These comments support the Service's proposal. We are 
grateful for the support of these nongovernmental organizations and 
recognize that partnerships are essential for the conservation of these 
species.
    (34) Comment: Western Pennsylvania Conservancy and Pennsylvania 
Biological Survey provided clarifications on historical and current 
information on populations of the sheepnose in Pennsylvania.
    Our Response: We appreciate the submission of the updated 
information. The updates have been incorporated into this final rule.
    (35) Comment: The Nature Conservancy in West Virginia, Virginia, 
Kentucky, and Ohio commented that several of the rivers with extant 
populations of both species are within the Conservancy's freshwater 
portfolio as places important for the conservation of freshwater 
diversity, and they stressed the importance of continued conservation 
of those areas.
    Our Response: These comments support the Service's proposal. We are 
grateful for support of these nongovernmental organizations and 
recognize that partnerships are essential for the conservation of these 
species in priority rivers established by The Nature Conservancy in 
these states and elsewhere.
    (36) Comment: The Nature Conservancy in West Virginia, Virginia, 
Kentucky, and Ohio, and the Pennsylvania Biological Survey commented on 
additional threats to both species from recent and legacy energy 
development and activities (for example, coal mining, gas drilling, 
energy transmission, and development infrastructure) and their 
potential impacts to mussel habitat and water quality.
    Our Response: These comments support the Service's proposal. 
Discussion on these threats was included under Factor A: The Present or 
Threatened Destruction, Modification,

[[Page 14933]]

or Curtailment of Their Habitat or Range and Factor E: Other Natural or 
Manmade Factors Affecting Their Continued Existence.
    (37) Comment: The Nature Conservancy in West Virginia, Virginia, 
Kentucky, and Ohio expressed their support of continued propagation and 
restoration efforts and noted some of the complexities that may 
surround those efforts.
    Our Response: These comments support the Service's proposal. We are 
grateful for support of these nongovernmental organizations and 
recognize that partnerships are essential for the conservation of these 
species. Propagation and restoration efforts will be investigated 
further under recovery planning and implementation for both species.
    (38) Comment: The Nature Conservancy in West Virginia, Virginia, 
Kentucky, and Ohio, commented on the importance of restoring host fish 
passage in the Ohio River in order to promote the recolonization of 
both species via their host fish. The Ohio River Basin Fish Habitat 
Partnership was recently formed to protect, restore, and enhance 
priority habitat for fish and mussels in the Ohio River Basin. The 
Partnership aims to improve and reconnect stream habitats. The Nature 
Conservancy is working with the Partnership and others to explore 
improving fish passage on the Ohio River.
    Our Response: These comments support the Service's proposal. We are 
grateful for support of these nongovernmental organizations and 
recognize that partnerships are essential for the conservation of these 
species. Restoration issues will be investigated further under recovery 
planning and implementation for both species.
    (39) Comment: The Nature Conservancy, Pennsylvania Biological 
Survey, and Western Pennsylvania Conservancy provided information on 
threats to the sheepnose from natural gas extraction from the Marcellus 
Shale formation.
    Our Response: We appreciate the submission of information on the 
potential threats of natural gas extraction as it supports our 
assumption that this activity could threaten multiple populations of 
the sheepnose. The information has been incorporated into this final 
rule under Factor A: The Present or Threatened Destruction, 
Modification, or Curtailment of Their Habitat or Range.
    (40) Comment: The Western Pennsylvania Conservancy provided 
information on the potential future threats to the sheepnose from 
natural gas extraction from the Utica Shale formation within the Ohio 
River drainage.
    Our Response: We appreciate the submission of information on the 
potential threats of natural gas extraction as it supports our 
assumption that this activity could threaten multiple populations of 
the sheepnose. The information has been incorporated into this final 
rule under Factor A: The Present or Threatened Destruction, 
Modification, or Curtailment of Their Habitat or Range.
    (41) Comment: The Pennsylvania Biological Survey and the Western 
Pennsylvania Conservancy commented on the large proportion of sheepnose 
habitat that has been eliminated in the Allegheny and Ohio Rivers since 
the construction of dams and the navigational pools, which may be the 
biggest cause of decline for the sheepnose in Pennsylvania.
    Our Response: We appreciate the submission of this information. 
These comments support the Service's proposal. The information has been 
incorporated into this final rule under Factor A: The Present or 
Threatened Destruction, Modification, or Curtailment of Their Habitat 
or Range.
    (42) Comment: American Rivers commented that both species are 
threatened by habitat destruction and curtailment, particularly, 
habitat loss due to isolation by barriers, impoundments, and 
channelization, along with reduced water quality caused by wastewater 
discharges, nonpoint-source pollution, agricultural runoff, and 
invasive species. American Rivers has a record of advocacy and action 
regarding dam removal, river restoration, and water quality 
improvement.
    Our Response: These comments support the Service's proposal. We are 
grateful for support of these nongovernmental organizations and 
recognize that partnerships are essential for the conservation of these 
species. Further discussion regarding these topics are included under 
Factor A: The Present or Threatened Destruction, Modification, or 
Curtailment of Their Habitat or Range and Factor E. Other Natural or 
Manmade Factors Affecting Its Continued Existence of this final rule.
    (43) Comment: The Pennsylvania Biological Survey, the Western 
Pennsylvania Conservancy and American Rivers provided comments 
regarding black carp (Mylopharyngodon piceus), a notorious molluscivore 
(mussel-eater), as a potential threat.
    Our Response: We appreciate the submission of the information. 
These comments support the Service's proposal. Information on the black 
carp as a threat to these species has been incorporated into the rule 
under Factor E: Other Natural or Manmade Factors Affecting Their 
Continued Existence.
    (44) Comment: The Pennsylvania Biological Survey and the Western 
Pennsylvania Conservancy provided comments regarding didymo 
(Didymosphenia geminata), a diatomaceous alga, as a potential threat to 
the sheepnose since it has recently been reported in the Delaware River 
watershed.
    Our Response: We appreciate the submission of the information. 
These comments support the Service's proposal. Information on didymo as 
a threat to these species has been incorporated into this final rule 
under Factor E: Other Natural or Manmade Factors Affecting Their 
Continued Existence.
    (45) Comment: The Pennsylvania Biological Survey provided their 
concerns about sand and gravel mining in the Allegheny River and the 
potential for further degradation of habitat and water quality due to 
those activities.
    Our Response: We appreciate the submission of information on the 
potential threats of instream sand and gravel mining as it supports our 
assumption that this activity could threaten multiple sheepnose 
populations. Additional information has been incorporated into this 
final rule under Factor A: The Present or Threatened Destruction, 
Modification, or Curtailment of Their Habitat or Range.
    (46) Comment: The Western Pennsylvania Conservancy provided 
information on threats to the sheepnose from the flow management from 
the Kinzua Dam on the Allegheny River, which could subject the species 
to changes in the thermal or flow regimes. Current flow along the 
Allegheny River should be maintained or improved, where possible, in 
order to sustain downstream mussel populations. Flow management from 
the Kinzua Dam could be used to maintain mussel populations if faced 
with future climate change.
    Our Response: We appreciate the submission of information on the 
potential threats of water management as it supports our assumption 
that these activities could threaten multiple populations of the 
sheepnose. The information has been incorporated into this final rule 
under Factor A: The Present or Threatened Destruction, Modification, or 
Curtailment of Their Habitat or Range.

[[Page 14934]]

    (47) Comment: The Western Pennsylvania Conservancy commented that 
global climate change could be a major threat limiting future habitat 
availability for the sheepnose.
    Our Response: These comments support the Service's proposal. The 
potential effects of climate change on freshwater mussels are discussed 
under Factor E: Other Natural or Manmade Factors Affecting Its 
Continued Existence of this final rule. The effects of climate change 
may be further investigated during recovery planning and implementation 
for both species.
    (48) Comment: The Western Pennsylvania Conservancy commented that 
the status of the Allegheny River sheepnose population should not be 
``Improving.'' The sheepnose is likely extirpated from approximately 70 
miles of the Allegheny River. There is an apparently stable population 
in the middle of the river; however, this section of the river faces 
several threats that may affect the health of the river.
    Our Response: We appreciate the submission of the information on 
the status of the population of sheepnose in the Allegheny River. 
Additional information has been incorporated into this final rule 
describing historical populations of sheepnose in the Allegheny River 
that are now extirpated and that supports our assertion that the status 
of the Allegheny River population is improving.
    (49) Comment: The Western Pennsylvania Conservancy commented about 
the risk of toxic spills to sheepnose due to the proximity of 
commercial railroads to the Allegheny River and given the documented 
occasional railroad derailment and resulting spill of toxic materials.
    Our Response: We appreciate the submission of the information. 
Information on toxic spills as a threat to these species has been 
incorporated into this final rule under Factor A: The Present or 
Threatened Destruction, Modification, or Curtailment of Their Habitat 
or Range.
    (50) Comment: American Rivers commented that it supports the 
designation of critical habitat for both species.
    Our Response: We determined that, although the designation of 
critical habitat is prudent, it is not determinable at this time. 
Therefore, we did not propose critical habitat in the proposed listing 
rule and no critical habitat is designated with this final listing 
rule. We will use information provided to us in developing a future 
critical habitat proposal. Once a proposal is published, we will seek 
additional public comment on our proposed critical habitat designation.
    (51) Comment: The Western Pennsylvania Conservancy commented that 
the implications of designating critical habitat to the repatriation of 
the sheepnose to presently unoccupied portions of its past range should 
be taken into consideration should it be restored to those presently 
extirpated areas.
    Our Response: We determined that, although the designation of 
critical habitat is prudent, it is not determinable at this time. 
Therefore, we did not propose critical habitat in the proposed listing 
rule and no critical habitat is designated with this final listing 
rule. We will use information provided to us and consider whether 
designating unoccupied habitat is appropriate in developing a future 
critical habitat proposal. Once a proposal is published, we will seek 
additional public comment on our proposed critical habitat designation.
    (52) Comment: American Rivers commented that both species benefit 
from the protections such as the Wild and Scenic and National Scenic 
Riverway in the St. Croix River basin of Wisconsin and Minnesota and 
receive indirect benefits from their work to restore more natural 
riverine conditions throughout Mississippi River tributaries.
    Our Response: We are grateful for support of these nongovernmental 
organizations and recognize that partnerships are essential for the 
conservation of these species.
    (53) Comment: The Columbia Power and Water Systems, Tennessee, did 
not support the proposed rule to list either species believing that the 
data we presented were inadequate to make such a decision. They also 
thought that strict permit conditions for water withdrawals and 
wastewater discharges will damage local economies. Finally, they stated 
that conservation measures to maintain or create critical habitat is an 
abuse of Federal power.
    Our Response: In weighing the data on the current population status 
of these species and threats to their continued existence, we have 
determined that they both warrant endangered status. Under the Act, a 
decision to list a species is made solely on the basis of the best 
scientific and commercial data available, and does not consider 
potential economic impacts. We used the best scientific and commercial 
data available in developing this final listing rule. We determined 
that, although the designation of critical habitat is prudent, it is 
not determinable at this time. Therefore, we did not propose critical 
habitat in the proposed listing rule and no critical habitat is 
designated with this final listing rule. We will use information 
provided to us in developing a future critical habitat proposal. Once a 
proposal is published, we will seek additional public comment on our 
proposed critical habitat designation. When critical habitat is 
designated, the Service must take into consideration the potential 
economic impact, as well as any other benefits or impacts, of 
specifying any particular area as critical habitat. Any area may be 
excluded from critical habitat if it is determined that the benefits of 
excluding it outweigh the benefits of specifying the area as part of 
critical habitat, unless the Service determines that the failure to 
designate the area as critical habitat will result in the extinction of 
the species.
    (54) Comment: The Columbia Power and Water Systems commented that 
the entire Duck River watershed should not be included in critical 
habitat designation.
    Our Response: We determined that, although the designation of 
critical habitat is prudent, it is not determinable at this time. 
Therefore, we did not propose critical habitat in the proposed listing 
rule and no critical habitat is designated with this final listing 
rule. We will use information provided to us in developing a future 
critical habitat proposal. Once a proposal is published, we will seek 
additional public comment on our proposed critical habitat designation.
    (55) Comment: The Columbia Power and Water Systems commented that 
the entire Duck River should not be included in either species' range. 
Only four collections of both species is not justification for 
including the entire watershed.
    Our Response: The commenter did not provide additional information 
to support their position. The spectaclecase and sheepnose are both 
considered to be extant in the Duck River (Tennessee River drainage), 
although both species were likely always rare in the Duck River (Hubbs 
2008, pers. comm.; Ahlstedt et al. 2004, pp. 14-15, 24). A single 
spectaclecase was recently found live in lower Duck River, Hickman 
County (Hubbs 1999, p. 1; Powell 2008, pers. comm.; Ahlstedt et al. 
2004, pp. 14-15), at least two individuals have been documented from 
the lower part of the river in Humphreys County, and several relic 
specimens have been reported farther upstream (Hubbs 2008, pers. comm.; 
Powell 2008, pers. comm.). These records of spectaclecase cover an 
approximately 20-mile (32-km) reach of river. One live individual 
sheepnose was collected in

[[Page 14935]]

the Duck River in 2003 (Saylors 2008, pers. comm.; Ahlstedt et al. 
2004, p. 24). Further discussion regarding this topic is under the 
Background section of this final rule.
    (56) Comment: The Columbia Power and Water Systems suggested the 
economic impacts of critical habitat should be determined prior to any 
decision being made. Local watershed economic development agencies 
should be given the opportunity to provide input regarding economic 
harm caused by this rule.
    Our Response: We determined that, although the designation of 
critical habitat is prudent, it is not determinable at this time. When 
critical habitat is proposed for the species, we will seek additional 
public comment on our proposed designation. When critical habitat is 
designated, the Service must take into consideration the potential 
economic impact, as well as any other benefits or impacts, of 
specifying any particular area as critical habitat. Local watershed 
economic development agencies will be given the opportunity to provide 
input on this economic analysis. Any area may be excluded from critical 
habitat if it is determined that the benefits of excluding it outweigh 
the benefits of specifying the area as part of critical habitat, unless 
the Service determines that the failure to designate the area as 
critical habitat will result in the extinction of the species.
    (57) Comment: The Service received two comments from individuals 
supporting the proposal to list both species. We received two 
additional comments from individuals that provided anecdotal 
information without expressing clear support or disapproval of the 
rule.
    Our Response: We are grateful for support of private citizens and 
recognize that partnerships are essential for the conservation of these 
species. These comments support the Service's proposal.
    (58) Comment: The Service received information from one individual 
who expressed concern over the proposal's lack of specificity on how 
the Service plans to halt and reverse the declining populations of both 
species. The commenter is concerned how the Service plans to address 
threats such as the zebra mussel, and wanted more information on the 
host identification studies. The commenter was interested to know if 
the Service plans to engage in a public policy campaign to encourage 
practices among lay people that would benefit the mussels, and if so, 
details of these actions.
    Our Response: We are grateful for the support of private citizens 
and recognize that partnerships are essential for the conservation of 
these species. This final rule cites several documents that give 
further detail of both species' life history, threats, and host 
identification. Further discussion on the threats of invasive species, 
host identification, and outreach will be discussed during recovery 
planning and implementation for both species.

Summary of Changes From the Proposed Rule

    We have considered all comments and information received during the 
open comment period for the proposed rule to list the spectaclecase and 
sheepnose as endangered. In this final rule, we modified the historical 
range of the spectaclecase to exclude the state of Nebraska, which was 
erroneously included in the proposed rule. In addition, based on the 
recent discovery of live spectaclecase in the Osage River, the number 
of rivers with extant populations of spectaclecase increased from 19 to 
20 rivers. We have also increased the number of extant populations of 
sheepnose from 24 to 25 based on a collection in the Rock River in 
2007, and removed one extant sheepnose record from Pool 3 of the 
Mississippi River from 2001 as it was not a fresh dead shell but a 
relict shell found during the 2001 survey (Minnesota Department of 
Natural Resources 2011). We also removed an historical occurrence of 
sheepnose from Hemlock Creek in Pennsylvania as the record was actually 
from the Allegheny River at the mouth of Hemlock Creek. We have 
included Marcellus shale extraction under Factor A: The Present or 
Threatened Destruction, Modification, or Curtailment of Its Habitat or 
Range and added other invasive species (didymo and golden algae) under 
Factor E: Other Natural or Manmade Factors Affecting Its Continued 
Existence in this final rule.

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533), 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 determine a species to 
be endangered or threatened due to one or more 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; or (E) other natural or manmade factors affecting its 
continued existence. Listing actions may be warranted based on any of 
the above threat factors, singly or in combination. Each of these 
factors is discussed below.

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

    The decline of mussels such as the spectaclecase and sheepnose is 
primarily the result of habitat loss and degradation (Neves 1991, pp. 
252, 265). Chief among the causes of decline are impoundments, 
channelization, chemical contaminants, mining, oil and gas development, 
and sedimentation (Neves 1991, pp. 252, 260-261; Neves 1993, pp. 1-7; 
Neves et al. 1997, pp. 63-72; Strayer et al. 2004, pp. 435-437; Watters 
2000, pp. 261-268; Williams et al. 1993, p. 7). These threats to 
mussels in general (and spectaclecase and sheepnose where specifically 
known) are individually discussed below.
Dams and Impoundments
    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, 
decrease habitat heterogeneity, affect normal flood patterns, and block 
upstream and downstream movement of species (Layzer et al. 1993, pp. 
68-69; Neves et al. 1997, pp. 63-64; Watters 2000, pp. 261-264). Within 
impounded waters, decline of freshwater mollusks has been attributed to 
sedimentation, decreased dissolved oxygen, and alteration in resident 
fish populations (Neves et al. 1997, pp. 63-64; Pringle et al. 2009, 
pp. 810-815; Watters 2000, pp. 261-264). Dams significantly alter 
downstream water quality and habitats (Allen and Flecker 1993, p. 36), 
and negatively affect tailwater mussel populations (Layzer et al. 1993, 
p. 69; Neves et al. 1997, p. 63; Watters 2000, pp. 265-266). Below 
dams, including those operated to generate hydroelectric power, mussel 
declines are associated with changes and fluctuation in flow regime, 
scouring and erosion, reduced dissolved oxygen levels and water 
temperatures, and changes in resident fish assemblages (Layzer et al. 
1993, p. 69; Neves et al. 1997, pp. 63-64; Pringle et al. 2009, pp. 
810-815; Watters 2000, pp. 265-266; Williams et al. 1992, p. 7). The 
decline and imperilment of freshwater mussels in several tributaries 
within the Tennessee, Cumberland, Mississippi, Missouri, and Ohio River 
basins have been directly attributed to construction of numerous 
impoundments in those

[[Page 14936]]

river systems (Hanlon et al. 2009, pp. 11-12; Layzer et al. 1993, pp. 
68-69; Miller et al. 1984, p. 109; Neves et al. 1997, pp. 63-64; Sickel 
et al. 2007, pp. 71-78; Suloway 1981, pp. 237-238; Watters 2000, pp. 
262-263; Watters and Flaute 2010, pp. 3-7; Williams and Schuster 1989, 
pp. 7-10).
    Population losses due to impoundments have likely contributed more 
to the decline and imperilment of the spectaclecase and the sheepnose 
than any other factor. Large river habitat throughout nearly all of the 
range of both species has been impounded, leaving generally short, 
isolated patches of vestigial habitat in the area below dams. 
Navigational locks and dams, (for example, on the upper Mississippi, 
Ohio, Allegheny, Muskingum, Kentucky, Green, and Barren Rivers), some 
high-wall dams (for example, on the Wisconsin, Kaskaskia, Walhonding, 
and Tippecanoe Rivers), and many low-head dams (for example, on the St. 
Croix, Chippewa, Flambeau, Wisconsin, Kankakee, and Bourbeuse Rivers) 
have contributed significantly to the loss of sheepnose and 
spectaclecase habitat (Butler 2002a, pp. 11-20 2002b, pp. 9-25).
    The majority of the Tennessee and Cumberland River main stems and 
many of their largest tributaries are now impounded. There are 36 major 
dams located in the Tennessee River system, and about 90 percent of the 
Cumberland River downstream of Cumberland Falls (RM 550 (RKM 886)) is 
either directly impounded by U.S. Army Corps of Engineers (Corps) 
structures or otherwise impacted by cold tail water released from 
several dams. Major Corps impoundments on Cumberland River tributaries 
(for example, Stones River and Caney Fork) have inundated an additional 
100 miles (161 km) or more of spectaclecase and sheepnose habitat. 
Coldwater releases from Wolf Creek, Dale Hollow (Obey River), and 
Center Hill (Caney Fork) Dams continue to degrade spectaclecase and 
sheepnose habitat in the Cumberland River system. For example, the 
scouring effects caused by 40 years of operation of the Center Hill Dam 
for hydroelectric power generation has dramatically altered the river 
morphology for 7 miles (12 km) downstream of the dam (Layzer et al. 
1993, p. 69). Layzer et al. (1993, p. 68) reported that 37 of the 60 
pre-impoundment mussel species of the Caney Fork River have been 
extirpated. Watters (2000, pp. 262-263) summarizes the tremendous loss 
of mussel species from various portions of the Tennessee and Cumberland 
River systems. Approximately one-third of the historical sheepnose and 
spectaclecase streams are in the Tennessee and Cumberland River 
systems.
    Navigational improvements on the Ohio River began in 1830, and now 
include 21 lock and dam structures stretching from Pittsburgh, 
Pennsylvania, to Olmsted, Illinois, near its confluence with the 
Mississippi River. Historically, habitat now under navigational pools 
once supported up to 50 species of mussels, including the spectaclecase 
and sheepnose. Tributaries to the Ohio River, such as the Green and 
Allegheny Rivers, were also altered by impoundments. The Allegheny 
River once supported sheepnose populations in what are now Pools 5-8; 
however, all of the sheepnose in the navigation pools have been 
extirpated, and the only remaining population exists above Pool 9 and 
below the Kinzua Dam (Urban pers. comm. 201, Smith and Meyer 2010, p. 
558). The fluctuating water levels released from the Kinzua Dam and 
Reservoir on the Allegheny River may have an impact on this last 
remaining sheepnose population, which is located approximately 25 miles 
(40 km) downstream. A series of six locks and dams was constructed on 
the lower half of the Green River decades ago and extend upstream to 
the western boundary of Mammoth Cave National Park (MCNP). The upper 
two locks and dams destroyed spectaclecase habitat, particularly Lock 
and Dam 6, which flooded the central and western portions of MCNP. 
Approximately 30 river miles (48 km) of mainstem habitat were also 
eliminated with the construction of the Green River Dam in 1969. Locks 
and dams were also constructed on the lower reaches of the Allegheny, 
Kanawha, Muskingum, and Kentucky Rivers, which disrupted historical 
riverine habitat for the sheepnose.
    Similarly, dams impound most of the upper Mississippi River and 
many of its tributaries. A series of 29 locks and dams constructed 
since the 1930s in the mainstem resulted in profound changes to the 
nature of the river, primarily replacing a free-flowing alluvial (flood 
plain) system with a stepped gradient (higher pool area to riffle area 
ratio) river. Modifications fragmented the mussel beds where 
spectaclecase and sheepnose were found in the Mississippi River, 
reduced stable riverine habitat, and disrupted fish host migration and 
habitat use.
    Dams and impoundments have fragmented and altered stream habitats 
throughout the Sac River Basin in the lower Missouri River system. 
Stockton Dam impounds 39 miles (63 km) of the upper Sac River, and the 
Truman Dam inundates about 8 miles (13 km) of the lower Sac River and 
its tributaries (Hutson and Barnhart 2004, p. 7). The rarity of live 
spectaclecase in the Sac River, coupled with the large number of dead 
shells observed in a recent study, suggests that this species has 
decreased since the river was impounded, and that spectaclecase may 
soon be extirpated from the Sac River system (Hutson and Barnhart 2004, 
p. 17).
    Dam construction has a secondary effect of fragmenting the ranges 
of aquatic mollusk species, leaving relict habitats and populations 
isolated by the structures as well as by extensive areas of deep 
uninhabitable, impounded waters. These isolated populations are unable 
to naturally recolonize suitable habitat that is impacted by temporary, 
but devastating events, such as severe drought, chemical spills, or 
unauthorized discharges (Cope et al. 1997, pp. 235-237; Layzer et al. 
1993, pp. 68-69; Miller and Payne 2001, pp. 14-15; Neves et al. 1997, 
pp. 63-75; Pringle et al. 2009, pp. 810-815; Watters 2000, pp. 264-265, 
268; Watters and Flaute 2010, pp. 3-7).
Sedimentation
    Nonpoint source pollution from land surface runoff originates from 
virtually all land use activities and includes sediments; fertilizer, 
herbicide, and pesticide residues; animal or human wastes; septic tank 
leakage and gray water discharge; and oils and greases. Nonpoint-source 
pollution can cause excess sedimentation, nutrification, decreased 
dissolved oxygen concentration, increased acidity and conductivity, and 
other changes in water chemistry that can negatively impact freshwater 
mussels. Land use types around the sheepnose and spectaclecase 
populations include pastures, row crops, timber, and urban and rural 
communities.
    Excessive sediments are believed to impact riverine mollusks 
requiring clean, stable streams (Brim Box and Mosa 1999, p. 99; Ellis 
1936, pp. 39-40). Impacts resulting from sediments have been noted for 
many components of aquatic communities. For example, sediments have 
been shown to affect respiration, growth, reproductive success, and 
behavior of freshwater mussels, and to affect fish growth, survival, 
and reproduction (Waters 1995, pp. 173-175). Potential sediment sources 
within a watershed include virtually all activities that disturb the 
land surface, and most localities currently occupied by the 
spectaclecase and sheepnose are affected to varying degrees by 
sedimentation.
    Sedimentation has been implicated in the decline of mussel 
populations

[[Page 14937]]

nationwide, and is a threat to spectaclecase and sheepnose (Brim Box 
and Mosa 1999, p. 99; Dennis 1984, p. 212; Ellis 1936, pp. 39-40; 
Fraley and Ahlstedt 2000, pp. 193-194; Poole and Downing 2004, pp. 119-
122; Vannote and Minshall 1982, pp. 4105-4106). Specific biological 
impacts include reduced feeding and respiratory efficiency from clogged 
gills, disrupted metabolic processes, reduced growth rates, limited 
burrowing activity, physical smothering, and disrupted host fish 
attractant mechanisms (Ellis 1936, pp. 39-40; Hartfield and Hartfield 
1996, p. 373; Marking and Bills 1979, p. 210; Vannote and Minshall 
1982, pp. 4105-4106; Waters 1995, pp. 173-175). In addition, mussels 
may be indirectly affected if high turbidity levels significantly 
reduce the amount of light available for photosynthesis and thus the 
production of certain food items (Kanehl and Lyons 1992, p. 7).
    Studies indicate that the primary impacts of excess sediment on 
mussels are sublethal, with detrimental effects not immediately 
apparent (Brim Box and Mosa 1999, p. 101). The physical effects of 
sediment on mussels are multifold, and include changes in suspended and 
bed material load; changes in bed sediment composition associated with 
increased sediment production and run-off in the watershed; changes in 
the form, position, and stability of channels; changes in depth or the 
width-to-depth ratio, which affects light penetration and flow regime; 
actively aggrading (filling) or degrading (scouring) channels; and 
changes in channel position that may leave mussels stranded (Brim Box 
and Mosa 1999, pp. 109-112; Kanehl and Lyons 1992, pp. 4-5; Vannote and 
Minshall 1982, p. 4106). The Chippewa River in Wisconsin, for example, 
has a tremendous bedload composed primarily of sand that requires 
dredging to maintain barge traffic on the mainstem Mississippi below 
its confluence (Thiel 1981, p. 20). The mussel diversity in the 
Mississippi River below the confluence with the Chippewa River has 
predictably declined from historical times. Lake Pepin, a once natural 
lake formed in the upper Mississippi River upstream from the mouth of 
the Chippewa River, has become increasingly silted in over the past 
century, reducing habitat for the spectaclecase and sheepnose (Thiel 
1981, p. 20).
    Increased sedimentation and siltation may explain in part why 
spectaclecase and sheepnose mussels appear to be experiencing 
recruitment failure in some streams. Interstitial spaces in the 
substrate provide crucial habitat for juvenile mussels. When clogged, 
interstitial flow rates and spaces are reduced (Brim Box and Mosa 1999, 
p. 100), thus reducing juvenile habitat. Furthermore, sediment may act 
as a vector for delivering contaminants such as nutrients and 
pesticides to streams, and juveniles may ingest contaminants adsorbed 
to silt particles during normal feeding activities. Female 
spectaclecase and sheepnose produce conglutinates that attract hosts. 
Such a reproductive strategy depends on clear water during the critical 
time of the year when mussels are releasing their glochidia.
    Agricultural activities produce the most significant amount of 
sediment that enters streams (Waters 1995, pp. 17-18). Neves et al. 
(1997, p. 65) stated that agriculture (including both sediment and 
chemical runoff) affects 72 percent of the impaired river miles in the 
country. Unrestricted livestock access occurs on many streams and 
potentially threatens their mussel populations (Fraley and Ahlstedt 
2000, pp. 193-194). Grazing may reduce infiltration rates and increase 
runoff; trampling and vegetation removal increases the probability of 
erosion (Armour et al. 1991, pp. 8-10; Brim Box and Mosa 1999, p. 103). 
The majority of the remaining spectaclecase and sheepnose populations 
are threatened by some form of agricultural runoff (nutrients, 
pesticides, sediment). Copper Creek, a tributary to the Clinch River, 
for example, has a drainage area that contains approximately 41 percent 
agricultural land (Hanlon et al. 2009, p. 3). Fraley and Ahlstedt 
(2000, p. 193) and Hanlon et al. (2009, pp. 11-12) attributed the 
decline of the Copper Creek mussel fauna to an increase in cattle 
grazing and resultant nutrient enrichment and loss of riparian 
vegetation along the stream, among other factors. This scenario is 
similar in other parts of the extant range of the spectaclecase and 
sheepnose.
    Sedimentation and urban runoff may also be threats to the sheepnose 
in the Kankakee River system as the Chicago Metro area continues to 
expand. Declines in mussel diversity observed in the Ohio River are in 
part due to pollution from urban centers; in many of these areas the 
loss of diversity has not recovered from water quality problems that 
began prior to dam construction (Watters and Flaute 2010, pp. 3-7).
    As the spectaclecase primarily inhabits deep water along the 
outside of bends, it may be particularly vulnerable to siltation. The 
current often slackens in this habitat, more so than in riffles and 
runs where other mussel species are typically found, and suspended 
sediment settles out. Spectaclecase beds covered with a thick layer of 
silt have been observed in Missouri, often downstream from reaches with 
eroding banks (Roberts 2008c, pers. comm.).
Channelization
    Dredging and channelization activities have profoundly altered 
riverine habitats nationwide. Hartfield (1993, pp. 131-139), Neves et 
al. (1997, pp. 71-72), and Watters (2000, pp. 268-269) reviewed the 
specific effects of channelization on freshwater mussels. 
Channelization impacts stream physically (for example accelerated 
erosion, reduced depth, decreased habitat diversity, geomorphic 
instability, and loss of riparian vegetation) and biologically (for 
example decreased fish and mussel diversity, altered species 
composition and abundance, decreased biomass, and reduced growth rates) 
(Hartfield 1993, pp. 131-139). Channel construction for navigation 
increases flood heights (Belt 1975, p. 684), partly as a result of a 
decrease in stream length and an increase in gradient (Hubbard et al. 
1993, p. 137 (in Hartfield 1993, p. 131)). Flood events may thus be 
exacerbated, conveying into streams large quantities of sediment, 
potentially with adsorbed contaminants. Channel maintenance may result 
in profound impacts downstream (Stansbery 1970, p. 10), such as 
increases in turbidity and sedimentation, which may smother bottom-
dwelling organisms.
    Channel maintenance operations for commercial navigation have 
impacted habitat for the sheepnose and spectaclecase in many large 
rivers rangewide. Periodic channel maintenance may continue to 
adversely affect this species in the upper Mississippi, Ohio, 
Muskingum, and Tennessee rivers. Further modifications to the 
Mississippi River channel are anticipated with the authorization of the 
NESP (Water Resources Development Act of 2007 (Pub. L. 110-114)), which 
will consist of construction of larger locks and other navigation 
improvements downstream of MRP 14. Continual maintenance of the 
Mississippi River navigation channel requires dredging, wing and 
closing dam reconstruction and maintenance, and bank armoring. 
Dredging, maintenance, and construction activities destabilize instream 
fine sediments and continue to affect aquatic habitats. Spectaclecase 
tend to inhabit relatively deep water where they are particularly 
vulnerable to siltation. The current is slower in this habitat than in 
riffles and runs, and suspended sediment settles

[[Page 14938]]

out in greater volume. Dredging to maintain barge traffic on the 
Mississippi River below the mouth of the Chippewa River in Wisconsin 
has reduced mussel diversity due to the increase in unstable sand 
substrates (Thiel 1981, p. 20).
    Disposal of dredge materials can also be a major concern for mussel 
populations. A large amount of spoil (dredged earth and rock) was 
dumped directly on a mussel bed in the Muskingum River that included 
the sheepnose in the late 1990s (Watters 2010b, pers. comm.). Thousands 
of mussels were killed as the result of this single event. Watters and 
Dunn (1995 p. 231) also noted that the lower ends of two mussel beds 
coincided with the mouths of Wolf and Bear Creeks. This led them to 
surmise that pollutants, such as sediment loads or agricultural runoff, 
in their watersheds may adversely impact mussels in the mainstem 
Muskingum River below the confluences of Wolf Creek and Bear Creek.
    Mussels require a stable substrate to survive and reproduce and are 
particularly susceptible to channel instability (Neves et al. 1997, p. 
23; Parmalee and Bogan 1998). Channel and bank degradation have led to 
the loss of stable substrates in the Meramec River Basin. Roberts and 
Bruenderman (2000, pp. 7-8, 21-23) pointed to the loss of suitable 
stable habitat as a major cause of decline in mussel abundance at sites 
previously surveyed in 1979.
    The Tennessee River was once a stronghold for the spectaclecase 
(Ortmann 1924, p. 60; 1925, p. 327), and the sheepnose was originally 
known to occur in the Tennessee River and 10 of its tributaries 
(Ortmann 1925, p. 328). Periodic dredging is conducted in the mainstem 
of the Tennessee River to maintain the 9-foot navigational channel 
(Chance 2008, pers. comm.). Severe bank erosion is ongoing along some 
reaches of the river below Pickwick Landing Dam, with some sites losing 
several feet of stream bank per year (Hubbs 2008, pers. comm.).
    The upper Kankakee River in Indiana was channelized several decades 
ago. The sheepnose is now considered extirpated from the upper 
Kankakee, and is restricted to the unchannelized portion of the river 
in Illinois (Cummings 2010a, pers. comm.).
Mining
    Instream gravel mining has been implicated in the destruction of 
mussel populations (Hartfield 1993, pp. 136-138). Negative impacts 
associated with gravel mining include stream channel modifications 
(altered habitat, disrupted flow patterns, and sediment transport), 
water quality modifications (increased turbidity, reduced light 
penetration, and increased temperature), macroinvertebrate population 
changes (elimination, habitat disruption, and increased sedimentation), 
and changes in fish populations (impacts to spawning and nursery 
habitat and food web disruptions) (Kanehl and Lyons 1992, pp. 4-10).
    Heavy metal-rich drainage from coal mining and associated 
sedimentation has adversely impacted portions of the Tennessee River 
system in Virginia. Low pH commonly associated with mine runoff can 
reduce glochidial encystment (attachment) rates (Huebner and Pynnonen 
1992, pp. 2350-2353). Acid mine runoff may thus have local impacts on 
recruitment of the mussel populations close to mines. Similarly, heavy 
metal contaminated sediments associated with lead mining have 
negatively impacted mussel populations along several miles of the Big 
River, Missouri (Roberts et al. 2009 p. 20).
    Coal-related toxins in the Clinch River may explain the decline and 
lack of mussel recruitment at some sites in the Virginia portion of 
that stream (Ahlstedt 2008, pers. comm.). Patterns of mussel 
distribution and abundances have been found to be negatively correlated 
with proximity to coal-mining activities (Ahlstedt and Tuberville 1997, 
pp. 74-75). Known mussel toxicants, such as polycyclic aromatic 
hydrocarbons, heavy metals (for example, copper, manganese, and zinc), 
and other chemicals from coal mining and other activities contaminate 
sediments in the Clinch River (Ahlstedt and Tuberville 1997, p. 75). 
These chemicals are toxic to juvenile mussels (Ahlstedt and Tuberville 
1997, p. 75). Pollutant inputs to the Clinch River from a coal-burning 
power plant in Carbo, Virginia, were shown to increase mortality and 
reduce cellulolytic activity (breaking down cellulose) in transplanted 
mussels (Farris et al. 1988, pp. 705-706). Site-specific copper 
toxicity studies of unionid glochidia in the Clinch River showed that 
freshwater mussels as a group were generally sensitive to copper, the 
toxic constituent of the power plant effluent (Cherry et al. 2002, p. 
596). All of these studies indicate that coal mining related discharges 
may have local impacts on spectaclecase recruitment and survival in 
this river.
    Gravel-mining activities may also be a localized threat in some 
streams with extant sheepnose and spectaclecase populations. Gravel 
mining causes stream instability, increasing erosion, turbidity, and 
subsequent sediment deposition (Meador and Layzer 1998, pp. 8-9). 
Gravel mining is common in the Meramec River system. Between 1997 and 
2008, the Missouri Department of Natural Resources issued permits for 
102 sand- and gravel-mining sites in the Meramec River (Zeaman 2008, 
pers. comm.). Although rigid guidelines prohibited instream mining and 
required streamside buffers, a court ruling deauthorized the Corps from 
regulating these habitat protective measures. The Corps still retains 
oversight for gravel mining, but many mining operations do not fall 
under Corps jurisdiction (Roberts and Bruenderman 2000, p. 23). In the 
lower Tennessee River, mining is permitted in 18 reaches for a total of 
47.9 river miles (77.1 km) between the Duck River confluence and 
Pickwick Landing Dam, a distance of more than 95 miles (153 km) (Hubbs 
2008, pers. comm.). This is the reach where mussel recruitment has been 
noted for many rare species in recent years. These activities have the 
potential to impact the river's small sheepnose population. The 
Gasconade River and its tributaries have been subject to gravel mining 
and other channel modifying practices that accelerate channel 
destabilization. These physical habitat threats combined with poor 
water quality and agricultural nonpoint-source pollution are serious 
threats to all existing mussel fauna in the system. In their surveys of 
Pools 4-8 of the Allegheny River, Smith and Meyer (2010, p. 556) found 
higher species richness and population counts in the areas of the pools 
7 and 8 that were free of sand and gravel mining than areas where there 
were past or current mining permits.
Oil and Gas Development
    Coal, oil, and natural gas resources are present in some of the 
watersheds that are known to support sheepnose, including the Allegheny 
River. Exploration and extraction of these energy resources can result 
in increased siltation, a changed hydrograph, and altered water quality 
even at a distance from the mine or well field. Sheepnose habitat in 
larger streams can be threatened by the cumulative effects of multiple 
mines and well fields (adapted from Service 2008, p. 11).
    Coal, oil, and gas resources are present in a number of the basins 
where sheepnose occur, and extraction of these resources has increased 
dramatically in recent years, particularly in Pennsylvania and West 
Virginia. Although oil and gas extraction generally occurs away from 
the river, extensive road networks are required to construct and 
maintain wells. These road networks frequently cross or occur near 
tributaries, contributing sediment

[[Page 14939]]

to the receiving waterway. In addition, the construction and operation 
of wells may result in the discharge of brine. Point-source discharges 
are typically regulated; however, nonpoint inputs such as silt and 
other contaminants may not be sufficiently regulated, particularly 
those originating some distance from a waterway. In 2006, more than 
3,700 permits were issued for oil and gas wells by the Pennsylvania 
Department of Environmental Protection, which also issued 98 citations 
for permit violations at 54 wells (Hopey 2007; adapted from Service 
2008, p. 12).
    Recent advances in drilling technology and rising natural gas 
prices have attracted new interest in the natural gas held in the 
Marcellus Shale rock formation that underlies approximately two-thirds 
of Pennsylvania and portions of the States of New York and West 
Virginia (PA DEP 2010, p. 1). Similarly, the Utica Shale rock 
formation, which underlies the Marcellus Shale in many locations, may 
also be mined for natural gas in the foreseeable future (Bier 2011, 
pers. comm.; Urban 2011, pers. comm.). The hydraulic fracturing process 
of Marcellus Shale natural gas extraction typically requires about one 
million gallons of water for a vertical well to approximately five 
million gallons of water for a vertical well with a horizontal lateral 
(PA DEP 2010, p. 1). The used water, often referred to as ``frac 
returns'' must be reused in the next well or sent to an approved 
treatment facility before it is discharged into natural waterways. In 
Pennsylvania, there are currently few treatment facilities capable of 
treating Marcellus Shale frac returns fluids, which may have high total 
dissolved salts, particularly chlorides (Urban 2011, pers. comm.). In 
addition, infrastructure development associated with Marcellus Shale 
industry, such as dirt and gravel roads and pipeline construction, may 
increase sedimentation in rivers (Bier 2011, pers. comm.; Urban 2011, 
pers. comm.); erosion and sediment control plan requirements under 
State law (PA Code Chapter 102) require gas companies to use 
preventative measures to restore the site and vegetation within 9 
months of well completion (PA DEP 2010, p. 2).
Chemical Contaminants
    Chemical contaminants are ubiquitous throughout the environment and 
are considered a major threat in the decline of freshwater mussel 
species (Cope et al. 2008, p. 451; Richter et al. 1997, p. 1081; 
Strayer et al. 2004, p. 436; Wang et al. 2007a, p. 2029). Chemicals 
enter the environment through both point and nonpoint discharges 
including spills, 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 populations are adversely 
impacted.
    Chemical spills can be especially devastating to mussels because 
they may result in exposure of a relatively immobile species to 
extremely elevated 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 include:
     Massive mussel kills on the Clinch River at Carbo, 
Virginia, occurred from a power plant alkaline fly ash pond spill in 
1967, and a sulfuric acid spill in 1970 (Crossman et al. 1973, p. 6);
     Approximately 18,000 mussels of several species, including 
750 individuals from three endangered mussel species, were eliminated 
from the upper Clinch River near Cedar Bluff, Virginia in 1998, when an 
overturned tanker truck released 1,600 gallons (6,056 liters) of a 
chemical used in rubber manufacturing (Jones et al. 2001, p. 20; 
Schmerfeld 2006, p. 12); and
     An ongoing release of sodium dimethyl dithiocarbamate, a 
chemical used to reduce and precipitate hexachrome, starting in 1999 
impacted approximately 10 river miles (16 km) of the Ohio River and 
resulted in an estimated loss of one million mussels, including 
individuals from two federally listed species (DeVault 2009, pers. 
comm.; Clayton 2008c, pers. comm.).
    These are not the only instances where chemical spills have 
resulted in the loss of high numbers of mussels (Brown et al. 2005, p. 
1457; Jones et al. 2001, p. 20; Neves 1991, p. 252; Schmerfeld 2006, 
pp. 12-13), but are provided as examples of the serious threat chemical 
spills pose to mussel species. The sheepnose and spectaclecase are 
especially threatened by chemical spills because these spills can occur 
anywhere that highways with tanker trucks, industries, or mines overlap 
with sheepnose and spectaclecase distribution.
    Exposure of mussels to lower concentrations of contaminants more 
likely to be found in aquatic environments can also adversely affect 
mussels and result in the decline of freshwater 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 (for example, national 
water quality criteria) do not have data for freshwater mussel species 
or exclude data that are available for freshwater mussels (March et al. 
2007, pp. 2066-2067, 2073).
    Current research is now starting to focus on the contaminant 
sensitivity of freshwater mussel glochidia and newly-released juvenile 
mussels (Goudreau et al. 1993, pp. 219-222; Jacobson et al. 1997, p. 
2390; March et al. 2007, pp. 2068-2073; Valenti et al. 2006, pp. 2514-
2517; Valenti et al. 2005, pp. 1244-1245; Wang et al. 2007c, pp. 2041-
2046) and juveniles (Augspurger et al. 2003, p. 2569; Bartsch et al. 
2003, p. 2561; March et al. 2007, pp. 2068-2073; Mummert et al. 2003, 
p. 2549; Valenti et al. 2006, pp. 2514-2517; Valenti et al. 2005, pp. 
1244-1245; Wang et al. 2007b, pp. 2053-2055; Wang et al. 2007c, pp. 
2041-2046) to such contaminants as ammonia, metals, chlorine, and 
pesticides. The toxicity information presented in this section focuses 
on recent water-only laboratory acute (sudden and severe exposure) and 
chronic (prolonged or repeated exposure) toxicity tests with early life 
stages of freshwater mussels, using the standard testing methodology 
published by the American Society for Testing and Materials (ASTM) 
(American Society for Testing and Materials. 2008. Standard guide for 
conducting laboratory toxicity tests with freshwater mussels E2455-06. 
In Annual Book of ASTM Standards, Vol. 11.06. Philadelphia, PA, pp. 
1442-1493.) Use of this standard testing method generates consistent, 
reliable toxicity data with acceptable precision and accuracy (Wang et 
al. 2007a, p. 2035) and was used for toxicity tests on ammonia, copper, 
chlorine and select pesticides (Augspurger et al. 2007, p. 2025; 
Bringolf et al. 2007b, p. 2101; Bringolf et al. 2007c, p. 2087; Wang et 
al. 2007a, p. 2029; Wang et al. 2007b, p. 2048; Wang et al. 2007c, p. 
2036). Use of these tests has documented that, while mussels are 
sensitive to some contaminants, they are not universally sensitive to 
all contaminants (Augspurger et al. 2007, pp. 2025-2026).
    One chemical that is particularly toxic to early life stages of 
mussels is ammonia. Sources of ammonia include agricultural wastes 
(animal feedlots and nitrogenous fertilizers), municipal

[[Page 14940]]

wastewater treatment plants, and industrial waste (Augspurger et al. 
2007, p. 2026) as well as precipitation and natural processes 
(decomposition of organic nitrogen) (Augspurger et al. 2003, p. 2569; 
Goudreau et al. 1993, p. 212; Hickey and Martin 1999, p. 44; 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 in mussel microhabitats 
(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), which may be exacerbated by the effects of climate change, and 
may cause ammonia to become more problematic for juvenile mussels. The 
EPA-established ammonia water quality criteria (EPA 1985, pp. 94-99) 
may not be protective of mussels (Augspurger et al. 2003, p. 2572; 
Sharpe 2005, p. 28) under current and future climate conditions.
    Mussels are also affected by 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 (Jacobson et 
al. 1997, p. 2390; Keller and Zam 1991, p. 543; Naimo 1995, pp. 351-
355; Valenti et al. 2005, p. 1244). Metals occur in industrial and 
wastewater effluents and are often a result of atmospheric deposition 
from industrial processes and incinerators. Glochidia and juvenile 
freshwater mussels have recently been studied to determine the acute 
and chronic toxicity of copper to these life stages (Wang et al. 2007b, 
pp. 2048-2056; Wang et al. 2007c, pp. 2036-2047). The chronic values 
determined for copper ranged from 8.5 to 9.8 micrograms per liter (ug/
L) for survival and from 4.6 to 8.5 ug/L for growth of juveniles. These 
chronic values are below the EPA 1996 chronic water quality criterion 
of 15 ug/L (hardness 170 mg/L) for copper (Wang et al. 2007b, pp. 2052-
2055). March (2007, pp. 2066, 2073) identifies 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. One recent study evaluated the 
sensitivity of early life stages of mussels to mercury (Valenti et al. 
2005, p. 1242). This study determined that, for the mussel species used 
(rainbow mussel, Villosa iris), glochidia were more sensitive to 
mercury than were juvenile mussels, with the median lethal 
concentration value of 14 ug/L compared to 114 ug/L for the juvenile 
life stage. The chronic toxicity tests conducted determined that 
juveniles exposed to mercury greater than or equal to 8 ug/L exhibited 
reduced growth. These observed toxicity values exceed EPA's Criteria 
Continuous Concentration and Criteria Maximum Concentration, which are 
0.77 ug/L and 1.4 ug/L, respectively. 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, 3,770 monitored waters do 
not meet EPA standards for mercury in the United States (http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T, 
accessed 6/28/2010). Acute mercury toxicity was determined to be the 
cause of extirpation of a diverse mussel fauna for a 70-mile (112-km) 
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 and that might occur 
with greater frequency and magnitude as a result of climate change. 
Bauer (1988, p. 244) found that excessive nitrogen concentrations can 
be detrimental to the adult freshwater pearl mussel (Margaritifera 
margaritifera), as was evident by the positive linear relationship 
between mortality and nitrate concentration. Also, a study of mussel 
lifespan 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 that 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 pesticide runoff, overspray application to row crops, and lack 
of adequate riparian buffers. Agricultural pesticide applications often 
coincide with the reproductive and early life stages of mussel, 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 freshwater mussels even though some pesticides, such 
as glyphosate (Roundup), 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), a native freshwater mussel (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 L. siliquoidea glochidia were the most 
sensitive organism tested to date (Bringolf et al. 2007a, p. 2094). 
Roundup, 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). This study determined that chlorpyrifos was toxic to 
both L. siliquoidea 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 sheepnose and spectaclecase.
    A potential, but undocumented, threat to freshwater mussel species, 
including sheepnose and spectaclecase, are

[[Page 14941]]

contaminants referred to as ``emerging contaminants'' that are being 
detected in aquatic ecosystems at an increasing rate. Pharmaceuticals, 
hormones, and other organic contaminants have been detected downstream 
from urban areas and livestock production (Kolpin et al. 2002, p. 
1202). A large potential source of these emerging contaminants is 
wastewater being discharged through both permitted (National Pollutant 
Discharge Elimination System, or NPDES) and nonpermitted sites 
throughout the country. Permitted discharge sites are ubiquitous in 
watersheds with sheepnose and spectaclecase populations, providing 
ample opportunities for contaminants to impact the species (for 
example, there are more than 250 NPDES sites in the Meramec River, 
Missouri system, which harbors large, but declining, populations of 
sheepnose and spectaclecase; Roberts and Bruenderman 2000, p. 78).
    The information presented in this section represents some of the 
threats from chemical contaminants that have been documented both in 
the laboratory and field and demonstrates that chemical contaminants 
pose a substantial threat to sheepnose and spectaclecase. This 
information indicates the potential for contaminants from spills that 
are immediately lethal to species, to chronic contaminant exposure, 
which results in death, reduced growth, or reduced reproduction of 
sheepnose and spectaclecase to contribute to declining sheepnose and 
spectaclecase populations.
Summary of Factor A
    The decline of the freshwater mussels in the eastern United States 
is primarily the result of the long-lasting effects of habitat 
alterations such as impoundments, channelization, chemical 
contaminants, mining, oil and gas development, and sedimentation. 
Although efforts have been made to restore habitat in some areas, the 
long-term effects of large-scale and wide-ranging habitat modification, 
destruction, and curtailment will continue into the foreseeable future.
    In summary, dams and impoundments are considered an imminent threat 
of high magnitude to the sheepnose or spectaclecase because they alter 
water quality and flow, impair habitats, and increase fragmentation and 
isolation of mussel populations. Although most impoundment and 
channelization of rivers and streams occurred in the past, the ongoing 
effects caused by such activities pose an imminent threat of high 
magnitude to both species because of altered habitats, sedimentation, 
and the subsequent transformations in biological communities that 
occurred due to these changes. Likewise, continued maintenance of 
channelized waterways adds to these threats by further increasing 
sedimentation and siltation. Excess sedimentation is considered an 
imminent threat of high magnitude to the spectaclecase and sheepnose 
because it can reduce feeding and respiratory efficiency of these 
species. Furthermore, sediments can be a vector for chemical 
contaminants.
    Small populations of sheepnose and spectaclecase are vulnerable to 
the threat of detrimental chemical spills. Furthermore, exposure of 
mussels to low but ubiquitous concentrations of contaminants may not be 
immediately lethal but can reduce filtration efficiency, decrease 
growth and reproduction and induce behavioral changes in all life 
stages over time. Therefore, we conclude that chemical contamination 
currently represents an imminent threat of high magnitude to the 
sheepnose and spectaclecase.
    Instream sand and gravel mining represents an imminent threat of 
moderate to high magnitude to both species due to the effects of water 
quality and habitat impairments. Coal, oil and gas mining are an 
imminent threat, particularly to sheepnose, because these activities 
can cause increases in siltation, change the hydrology, and alter water 
quality.

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

    The spectaclecase and sheepnose are not commercially valuable 
species but may be increasingly sought by collectors as they become 
rarer. Although scientific collecting is not thought to represent a 
significant threat, unregulated collecting could adversely affect 
localized spectaclecase and sheepnose populations.
    Mussel harvest is illegal in some States (for example, Indiana and 
Ohio), but regulated in others (for example, Alabama, Kentucky, 
Tennessee, and Wisconsin). These species may be inadvertently harvested 
by inexperienced commercial harvesters unfamiliar with species 
identification. Although illegal harvest of protected mussel beds 
occurs (Watters and Dunn 1995, p. 225, 247-250), commercial harvest is 
not known to have a significant impact on the spectaclecase and 
sheepnose.
    On the basis of this analysis, we find that overutilization for 
commercial, recreational, scientific, or educational purposes is not 
now a threat to the spectaclecase or sheepnose in any portion of its 
range or likely to become a significant threat in the foreseeable 
future.

C. Disease or Predation

    Little is known about diseases in freshwater mussels (Grizzle and 
Brunner 2007, p. 6). However, mussel die-offs have been documented in 
spectaclecase and sheepnose streams (Neves 1986, p. 9), and some 
researchers believe that disease may be a factor contributing to the 
die-offs (Buchanan 1986, p. 53; Neves 1986, p. 11). Mussel parasites 
include water mites, trematodes, oligochaetes, leeches, copepods, 
bacteria, and protozoa (Grizzle and Brunner 2007, p. 4). Generally, 
parasites are not suspected of being a major limiting factor (Oesch 
1984, p. 6), but a recent study showed that reproductive output and 
physiological condition were negatively correlated with mite and 
trematode abundance, respectively (Gangloff et al. 2008, pp. 28-30). 
Stressors that reduce fitness may make mussels more susceptible to 
parasites (Butler 2007, p. 90). Furthermore, nonnative mussels may 
carry diseases and parasites that are potentially devastating to the 
native mussel fauna, including spectaclecase and sheepnose (Strayer 
1999, p. 88).
    The muskrat (Ondatra zibethicus) is cited as the most prevalent 
mussel predator (Convey et al. 1989, pp. 654-655; Hanson et al. 1989, 
pp. 15-16; Kunz 1898, p. 328). Muskrat predation may limit the recovery 
potential of endangered mussels or contribute to local extirpations of 
previously stressed populations, according to Neves and Odom (1989, p. 
940), but they consider it primarily a seasonal or localized threat. 
B[ouml]pple and Coker (1912, p. 9) noted the occurrence of ``large 
piles of shells made by the muskrats'' on an island in the Clinch 
River, Tennessee, composed of ``about one-third'' spectaclecase shells. 
Predation by muskrats may be a seasonal and localized threat to 
spectaclecase and sheepnose populations but is probably not a 
significant threat rangewide.
    Some species of fish feed on mussels (for example, common carp 
(Cyprinus carpio), freshwater drum (Aplodinotus grunniens), redear 
sunfish (Lepomis microlophus)) and potentially on this species when 
young. Various invertebrates, such as flatworms, hydra, nonbiting midge 
larvae, dragonfly larvae, and crayfish, may feed on juvenile mussels 
(Neves 2008, pers. comm.). Although predation by naturally occurring 
predators is a normal aspect of the population dynamics of a healthy 
mussel

[[Page 14942]]

population, predation may amplify declines in small populations of this 
species. In addition, the potential now exists for the black carp 
(Mylopharyngodon piceus), a mollusk-eating Asian fish recently 
introduced into the waters of the United States (Strayer 1999, p. 89), 
to eventually disperse throughout the range of the spectaclecase and 
sheepnose.
    The life cycle of freshwater mussels is intimately related to that 
of the freshwater fish they use as hosts for their parasitic glochidia. 
For this reason, diseases that impact populations of freshwater fishes 
also pose a significant threat to mussels. Viral hemorrhagic septicemia 
(VHS) disease has been confirmed from much of the Great Lakes and St. 
Lawrence River system. In June 2008, muskellunge (Esox masquinongy) 
from Clearfork Reservoir, near Mansfield, Ohio, tested positive for 
carrying VHS virus. This is the first known occurrence of VHS virus in 
the Mississippi River basin.
    The VHS virus has been implicated as a mortality factor in fish 
kills throughout the Great Lakes region. It has been confirmed in 28 
fish species, but no identified hosts for sheepnose are on the U.S. 
Department of Agriculture's Animal and Plant Health Inspection Service 
(APHIS) list of fish species susceptible to VHS (APHIS 2008, pp. 1-2). 
Since the host for spectaclecase is unknown, we do not know how VHS 
could affect reproduction for spectaclecase. If the VHS virus 
successfully migrates out of the Clearfork Reservoir and into the Ohio 
River, it could spread rapidly and cause fish kills throughout the 
Mississippi River basin. Few spectaclecase and sheepnose populations 
are currently recruiting at sustainable levels, and fish kills could 
further reduce encounters with hosts and potentially reduce 
recruitment.
    In summary, disease in freshwater mollusks is poorly known and not 
currently considered a threat to the sheepnose or spectaclecase. 
Although there is no direct evidence at this time that predation is 
detrimentally affecting the spectaclecase or sheepnose, their small 
populations and limited ranges leave them vulnerable to threats of 
predation from natural or introduced predators. Therefore, we conclude 
that predation currently represents a nonimminent threat of low 
magnitude, but it could potentially become a significant future threat 
to the spectaclecase and sheepnose due to their small population sizes.

D. The Inadequacy of Existing Regulatory Mechanisms

    States with extant spectaclecase and sheepnose populations prohibit 
the taking of mussels for scientific purposes without a State 
collecting permit. However, enforcement of this permit requirement can 
be difficult, for example, due to limited enforcement staff and the 
intricacies of species identification.
    The level of protection that spectaclecase and sheepnose receive 
from State listing varies from State to State. The sheepnose is State-
listed in every State that keeps such a list. Until January 1, 2011, 
collection of sheepnose in Pennsylvania for use as fish bait was 
allowed with a limit of 50 individuals per day; however, this 
regulation was recently changed such that collection of mussels for 
bait is no longer permitted (http://www.pabulletin.com/secure/data/vol40/40-51/2402.html). The spectaclecase is State-listed in 9 of the 
10 States that harbor extant populations. Only in Tennessee is the 
spectaclecase not assigned conservation status, and West Virginia does 
not have any State-specific legislation similar to the Act.
    Nonpoint-source pollution is considered a primary threat to 
sheepnose and spectaclecase habitat; however, current laws do not 
adequately protect spectaclecase and sheepnose habitat from nonpoint-
source pollution, as the laws to prevent sediment entering waterways 
are poorly enforced. Best management practices for sediment and erosion 
control are often recommended or required by local ordinances for 
construction projects; however, compliance, monitoring, and enforcement 
of these recommendations are often poorly implemented. Furthermore, 
there are currently no requirements within the scope of Federal 
environmental laws to specifically consider the spectaclecase and 
sheepnose during Federal activities.
    It is unknown if water extraction regulations sufficiently protect 
mussel habitat in mining areas. For instance, the Pennsylvania 
Department of Environmental Protection policy imposes a 20 percent 
average daily flow (a.d.f.) passby restriction on Marcellus Shale water 
withdrawals for warmwater streams and a 25 percent a.d.f. passby 
requirement for coldwater streams (Urban 2011, pers. comm.). The 
Susquehanna and Delaware River Basin Commissions have regulatory 
frameworks in place to monitor cumulative impacts to water withdrawals; 
however, there is no such mechanism in place in the Ohio River Basin 
(Urban 2011, pers. comm.). The effect of extracting large volumes of 
water to the maintenance of mussel habitat is unknown. Point source 
discharges within the range of the spectaclecase and sheepnose have 
been reduced since the inception of the Clean Water Act (33 U.S.C. 1251 
et seq.), but this may not provide adequate protection for filter 
feeding organisms that can be impacted by extremely low levels of 
contaminants (see ``Chemical Contaminants '' discussion under Factor A: 
The Present or Threatened Destruction, Modification, or Curtailment of 
Its Habitat or Range). There is no specific information on the 
sensitivity of the spectaclecase and sheepnose to common industrial and 
municipal pollutants, and very little information on other freshwater 
mussels. Therefore, it appears that a lack of adequate research and 
data prevents existing regulations, such as the Clean Water Act 
(administered by the EPA and the Corps), from being fully used or 
effective.
    The U.S. Army Corps of Engineers retains oversight authority and 
requires a permit for gravel-mining activities that deposit fill into 
streams under section 404 of the Clean Water Act. Additionally, a Corps 
permit is required under section 10 of the Rivers and Harbors Act (33 
U.S.C. 401 et seq.) for navigable waterways including the lower 50 
miles (80 km) of the Meramec River. However, many gravel-mining 
operations do not fall under these two categories.
    Despite these existing regulatory mechanisms, the spectaclecase and 
sheepnose continue to decline due to the effects of habitat 
destruction, poor water quality, contaminants, and other factors. These 
regulatory measures have been insufficient to significantly reduce or 
remove the threats to the spectaclecase and sheepnose mussels. 
Therefore the inadequacy of existing regulatory mechanisms is an 
imminent threat of moderate to high magnitude to these species 
throughout all of their ranges.
    Based on our analysis of the best available data, we have no reason 
to believe that the aforementioned regulations will offer adequate 
protection to the spectaclecase and sheepnose in the foreseeable 
future.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Temperature
    Natural temperature regimes can be altered by impoundments, water 
releases from dams, industrial and municipal effluents, and changes in 
riparian habitat. Critical thermal limits

[[Page 14943]]

for survival and normal functioning of many freshwater 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 (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 righting speed, increase oxygen consumption, and 
slow burrowing and movement responses (Bartsch et al. 2000, p. 237; 
Fuller 1974, pp. 240-241; Schwalb and Pusch 2007, pp. 264-265; Watters 
et al. 2001, p. 546). Several studies have documented the influence of 
temperature on the timing of aspects of mussel reproduction (for 
example, Allen et al. 2007, p. 85; Gray et al. 2002, p. 156; 
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 to mussels whose reproductive cycles may be linked to fish 
reproductive cycles (for example, Young and Williams 1984). Therefore, 
altered water temperatures is an imminent threat to sheepnose and 
spectaclecase with moderate to high magnitude, depending the timing of 
temperature changes and the thermal limits and stage in each species' 
development.
Climate Change
    It is a widely accepted fact that changes in climate are occurring 
worldwide (IPCC 2007, p. 30). Understanding the effects of climate 
change on freshwater mussels is of crucial importance, because the 
extreme fragmentation of freshwater drainage systems, coupled with the 
limited ability of mussels to migrate, will make it particularly 
difficult for mussels to adjust their range in response to changes in 
climate (Strayer 2008, p. 30). For example, changes in temperature and 
precipitation can increase the likelihood of flooding or increase 
drought duration and intensity, resulting in direct impacts to 
freshwater mussels (Golladay et al. 2004, p. 503; Hastie et al. 2003, 
pp. 40-43). Riverine mussel distribution appears to be highly dependent 
on complex hydraulic characteristics (for example, Morales et al. 2006, 
pp. 669-673; Zigler et al. 2008, p. 358). Indirect effects of climate 
change may include declines in host fish stocks, sea level rise, 
habitat reduction, and changes in human activity in response to climate 
change (Hastie et al. 2003, pp. 43-44). Therefore, we conclude that 
climate change currently represents a nonimminent threat that may 
become a future threat of high magnitude to the spectaclecase and 
sheepnose due to the limited ability of their fragmented populations to 
migrate.
Population Fragmentation and Isolation
    Most of the remaining spectaclecase and sheepnose populations are 
small and isolated. The patchy distributional pattern of populations in 
short river reaches makes them much more susceptible to extirpation 
from single catastrophic events, such as toxic chemical spills (Watters 
and Dunn 1993-94, p. 257). Furthermore, this level of isolation makes 
natural repopulation of any extirpated population unlikely without 
human intervention. 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 (Avise and 
Hambrick 1996, p. 461). Despite any evolutionary adaptations for 
rarity, habitat loss and degradation increase a species' vulnerability 
to extinction (Noss and Cooperrider 1994, pp. 58-62). Numerous authors 
(including Noss and Cooperrider 1994, pp. 58-62; Thomas 1994, p. 373) 
have indicated that the probability of extinction increases with 
decreasing habitat availability. Although changes in the environment 
may cause populations to fluctuate naturally, small and low-density 
populations are more likely to fluctuate below a minimum viable 
population (the minimum or threshold number of individuals needed in a 
population to persist in a viable state for a given interval) (Gilpin 
and Soule 1986, pp. 25-33; Shaffer 1981, p. 131; Shaffer and Samson 
1985, pp. 148-150).
    These species were widespread throughout much of the upper two-
thirds of the Mississippi River system, for example, when few natural 
barriers existed to prevent migration (via host species) among suitable 
habitats. Construction of dams, however, destroyed many spectaclecase 
and sheepnose populations and isolated others. Recruitment reduction or 
failure is a potential problem for many small sheepnose populations 
rangewide, a potential condition exacerbated by its reduced range and 
increasingly isolated populations. If these trends continue, further 
significant declines in total sheepnose population size and consequent 
reduction in long-term survivability may soon become apparent.
    Spectaclecase are long-lived (up to 70 years; Havlik 1994, p. 19), 
while sheepnose are relatively long-lived (approximately 30 years; 
Watters et al. 2009, p. 221) Therefore, it may take decades for 
nonreproducing populations of both species to become extinct following 
their isolation by, for example, the construction of a dam. The 
occasional discovery of relatively young spectaclecase in river reaches 
between impoundments indicates that some post-impoundment recruitment 
has occurred. The level of recruitment in these cases, however, appears 
to be insufficient to ensure the long-term sustainability of the 
spectaclecase. Small isolated populations of spectaclecase and 
sheepnose that may now be composed predominantly of adult specimens 
could be dying out slowly in the absence of recruitment, even without 
the other threats just described. Isolated populations usually face 
other threats that result in continually decreasing patches of suitable 
habitat.
    Genetic considerations for managing imperiled mussels and for 
captive propagation were reviewed by Neves (1997, p. 4) and Jones et 
al. (2006, pp. 527-535), respectively. The likelihood is high that some 
populations of the spectaclecase and sheepnose are below the effective 
population size (EPS) (Soule 1980, pp. 162-164) necessary to adapt to 
environmental change and persist in the long term. Isolated populations 
eventually die out when population size drops below the EPS or 
threshold level of sustainability. Evidence of recruitment in many 
populations of these two species is scant, making recruitment reduction 
or outright failure suspect. These populations may be experiencing the 
bottleneck effect of not attaining the effective population size. 
Small, isolated populations below the effective size-threshold of 
short-lived species (most host fishes) theoretically die out within a 
decade or so, while below-threshold populations of long-lived species, 
such as the spectaclecase and sheepnose, might take decades to die out 
even given years of total recruitment failure. Without historical 
barriers to genetic interchange, small, isolated populations could be 
slowly expiring, a phenomenon termed the extinction debt (Tilman et al. 
1994, pp. 65-66). Even given the totally improbable absence of 
anthropogenic threats, we may lose disjunct populations to below-
threshold effective-population size. However,

[[Page 14944]]

evidence indicates that general degradation continues to decrease 
habitat patch size and to act insidiously in the decline of 
spectaclecase and sheepnose populations.
    Spectaclecase and sheepnose mussels' scarcity and decreased 
population size makes maintaining adequate heterogeneity problematic 
for resource managers. Neves (1997, p. 6) warned that ``[i]f we let 
conservation genetics become the goal rather than the guidelines for 
restoring and recovering mussel populations, then we will be doomed to 
failure with rare species.'' Habitat alteration, not lack of genetic 
variability, is the driving force of population extirpation (Caro and 
Laurenson 1994, pp. 485-486; Neves et al. 1997, p. 60). Nevertheless, 
genetics issues should be considered in maintaining high levels of 
heterozygosity during spectaclecase recovery efforts. Treating disjunct 
occurrences of this wide-ranging species as a metapopulation would 
facilitate conservation management while increasing recovery options 
(for example, translocating adults or introducing infested hosts and 
propagated juveniles) to establish and maintain viable populations 
(Neves 1997, p. 6). Due to small population size and probable reduction 
of genetic diversity within populations, efforts should be made to 
maximize genetic heterogeneity to avoid both inbreeding (Templeton and 
Read 1984, p. 189) and outbreeding depression (Avise and Hamrick 1996, 
pp. 463-466) whenever feasible in propagation and translocation efforts 
(Jones et al. 2006, p. 529).
    Fragmentation and isolation of small remaining populations of the 
spectaclecase and sheepnose are imminent threats of high magnitude to 
both species throughout all of their ranges that will continue into the 
foreseeable future. Further, stochastic events may play a magnified 
role in population extirpation when small, isolated populations are 
involved.
Exotic Species
    Various exotic or nonnative species of aquatic organisms are firmly 
established in the range of the spectaclecase and sheepnose. The exotic 
species that poses the most significant threat to the spectaclecase and 
sheepnose is the zebra mussel (Dreissena polymorpha). Its invasion of 
freshwater habitats in the United States poses an imminent threat of 
high magnitude to mussel faunas in many regions, and species' 
extinctions are expected as a result of its continued spread in the 
eastern United States (Ricciardi et al. 1998, p. 615). Strayer (1999, 
pp. 75-80) reviewed in detail the mechanisms in which zebra mussels 
impact native mussels. The primary means of impact is direct fouling of 
the shells of live native mussels. Zebra mussels attach in large 
numbers to the shells of live native mussels and are implicated in the 
loss of entire native mussel beds. Fouling impacts include impeding 
locomotion (both laterally and vertically), interfering with normal 
valve movements, deforming valve margins, and locally depleting food 
resources and increasing waste products. Heavy infestations of zebra 
mussels on native mussels may overly stress the animals by reducing 
their energy stores. They may also reduce food concentrations to levels 
too low to support reproduction, or even survival in extreme cases.
    Other ways zebra mussels may impact spectaclecase and sheepnose is 
through filtering their sperm and possibly glochidia from the water 
column, thus reducing reproductive potential. Habitat for native 
mussels may also be degraded by large deposits of zebra mussel 
pseudofeces (undigested waste material passed out of the incurrent 
siphon) (Vaughan 1997, p. 11). Because spectaclecase are found in pools 
and zebra mussel veligers (larvae) attach to hard substrates at the 
point at which they settle out from the water column, spectaclecase are 
particularly vulnerable to zebra mussel invasion. The spectaclecase's 
colonial tendency could allow for very large numbers to be affected by 
a single favorable year for zebra mussels.
    Zebra mussels are established throughout the upper Mississippi, 
lower St. Croix, Ohio, and Tennessee Rivers, overlapping much of the 
current range of the spectaclecase and sheepnose. The greatest 
potential for present zebra mussel impacts to the spectaclecase and 
sheepnose appears to be in the upper Mississippi River. Kelner and 
Davis (2002, p. ii) stated that zebra mussels in the Mississippi River 
from Mississippi River Pool 4 downstream are ``extremely abundant and 
are decimating the native mussel communities.'' Huge numbers of dead 
and live zebra mussels cover the bottom of the river in some localities 
up to 1 to 2 inches (2.5 to 5.1 centimeters (cm)) deep (Havlik 2001a, 
p. 16), where they have reduced significantly the quality of the 
habitat with their pseudofeces (Fraley 2008b, pers. comm.). Zebra 
mussels likely have reduced spectaclecase and sheepnose populations in 
these heavily infested waters.
    As zebra mussels may maintain high densities in big rivers, large 
tributaries, and below infested reservoirs, spectaclecase and sheepnose 
populations in affected areas may be significantly impacted. For 
example, zebra mussel densities in the Tennessee River remained low 
until 2002, but are now abundant enough below Wilson Dam to be measured 
quantitatively (Garner 2008, pers. comm.). In addition, there is long-
term potential for zebra mussel invasions into other systems that 
currently harbor spectaclecase and sheepnose populations. Zebra mussels 
occur in the lower St. Croix River, one of the strongholds for 
spectaclecase, although it is unclear whether they are likely to spread 
much further upstream due to the transition from lake-like conditions 
to almost exclusively riverine conditions above RM 25.
    The Asian clam (Corbicula fluminea) has spread throughout the range 
of the spectaclecase and sheepnose since its introduction in the mid-
1900s. Asian clams compete with native mussels, especially juveniles, 
for food, nutrients, and space (Leff et al. 1990, p. 415; Neves and 
Widlak 1987, p. 6) and may ingest unionid sperm, glochidia, and newly 
metamorphosed juveniles of native mussels (Strayer 1999, p. 82; Yeager 
et al. 2000, p. 255). Dense Asian clam populations actively disturb 
sediments that may reduce habitat for juveniles of native mussels 
(Strayer 1999, p. 82).
    Asian clam densities vary widely in the absence of native mussels 
or in patches with sparse mussel concentrations, but Asian clam density 
is never 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 
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). Asian clams, 
therefore, are considered an imminent threat of low to moderate 
magnitude to the spectaclecase and sheepnose.
    A molluscivore (mollusk eater), the black carp (Mylopharyngodon 
piceus) is a potential threat to native mussels (Strayer 1999, p. 89); 
it has been introduced into North America since the 1970s. The species 
has been proposed for widespread use by aquaculturists to control 
snails, the intermediate host of a trematode (flatworm) parasite that

[[Page 14945]]

affects catfish in commercial culture ponds in the Southeast and lower 
Midwest. Black carp are known to eat clams (Corbicula spp.) and unionid 
mussels in China, in addition to snails. They are the largest of the 
Asian carp species, reaching more than 4 ft in length and achieving a 
weight in excess of 150 pounds (Nico and Williams 1996, p. 6). Foraging 
rates for a 4-year-old fish average 3 or 4 pounds (1.4-1.8 kg) a day, 
indicating that a single individual could consume 10 tons (9,072 kg) of 
native mollusks over its lifetime (Mississippi Interstate Cooperative 
Resource Association (MICRA) 2005, p. 1). In 1994, 30 black carp 
escaped from an aquaculture facility in Missouri during a flood. Other 
escapes into the wild by nonsterile black carp are likely to occur. 
Since black carp have not yet invaded all waters with spectaclecase and 
sheepnose populations, the threat of black carp is not universally 
imminent; however, black carp have the potential to become a threat of 
high magnitude once introduced into a system.
    The round goby (Neogobius melanostomus) is another exotic fish 
species released into the Great Lakes that is well established and 
likely to spread through the Mississippi River system (Strayer 1999, 
pp. 87-88). This species is an aggressive competitor of similar sized 
benthic fishes (sculpins, darters), as well as a voracious carnivore, 
despite its size (less than 10 in. (25.4 cm) in length), preying on a 
variety of foods, including small mussels and fishes that could serve 
as glochidial hosts (Janssen and Jude 2001, p. 325; Strayer 1999, p. 
88). Round gobies may, therefore, have important indirect effects on 
the spectaclecase and sheepnose through negative effects to their 
hosts. Similar to the black carp, the round goby are an imminent threat 
where they have been introduced, and have the potential to become a 
threat of moderate magnitude in those areas where they occur.
    The invasive golden algae (Prymnesium parvum), when under stress, 
are known to give off toxins that are lethal to gill-breathing 
organisms (Barkoh and Fries 2010, p. 1). Golden algae contributed to 
the 2009 aquatic life kill that destroyed the entire Dunkard Creek 
mussel population in the Monongahela River basin (US EPA 2009, p. 5). 
In streams with elevated total dissolved solids (TDS), golden algae 
outcompete native algae, and once golden algae is established, it is 
difficult to eradicate (US EPA 2009, p. 15). Golden algae dispersal may 
be linked to shale gas equipment moved from contaminated streams in the 
southwestern United States (Urban 2011, pers. comm.). Where found, 
golden algae is an imminent threat of high magnitude.
    Didymo (Didymosphenia geminata) is an invasive alga that covers the 
stream bottom in thick mats, smothering streambeds and adversely 
affecting aquatic organisms (Spaulding and Elwell 2007, pp. 5, 12, 16). 
Didymo has been discovered in watersheds near those occupied by 
sheepnose (for example, Delaware River watershed in Pennsylvania, 
http://www.fish.state.pa.us/water/habitat/ans/didymo/faq_didymo.htm).
    Additional exotic species will invariably become established in the 
foreseeable future (Strayer 1999, pp. 88-89). Added to potential direct 
threats, exotic species could carry diseases and parasites that may be 
devastating to the native biota. Because of our ignorance of mollusk 
diseases and parasites, ``it is imprudent to conclude that alien 
diseases and parasites are unimportant'' (Strayer 1999, p. 88). Didymo 
is a nonimminent threat that has a potential to become a threat of high 
magnitude once it is introduced into a system.
    Exotic species, such as those described above, are an imminent 
threat of moderate to high magnitude to the spectaclecase and 
sheepnose--a threat that is likely to increase in magnitude as these 
exotic species expand their occupancy within the ranges of the 
spectaclecase and sheepnose.

Summary of Threats

    The decline of the spectaclecase and sheepnose in the eastern 
United States (described by Butler 2002a, entire; Butler 2002b, entire) 
is primarily the result of habitat loss and degradation (Neves 1991, p. 
252). These losses have been well documented since the mid-19th century 
(Higgins 1858, p. 550). Chief among the causes of decline are 
impoundments, channelization, chemical contaminants, mining, and 
sedimentation (Neves 1991, p. 252; Neves 1993, pp. 4-6; Neves et al. 
1997, pp. 60, 63-75; Watters 2000, pp. 262-267; Williams et al. 1993, 
pp. 7-9). These stressors have had profound impacts on sheepnose and 
spectaclecase populations and their habitat.
    The majority of the remaining populations of the spectaclecase and 
sheepnose are generally small and geographically isolated (Butler 
2002a, p. 27; 2002b, p. 27). The patchy distributional pattern of 
populations in short river reaches makes them much more susceptible to 
extirpation from single catastrophic events, such as toxic chemical 
spills (Watters and Dunn 1995, p. 257). Furthermore, this level of 
isolation makes natural repopulation of any extirpated population 
virtually impossible without human intervention. In addition, the fish 
host of spectaclecase is unknown; thus, propagation to reestablish the 
species in restored habitats and to maintain nonreproducing populations 
and focused conservation of its fish host are currently not possible. 
Although there are ongoing attempts to alleviate some of these threats 
at some locations, there appear to be no populations without 
significant threats, and many threats are without obvious or readily 
available solutions.
    Recruitment reduction or failure is a threat for many small 
spectaclecase and sheepnose populations rangewide, a condition 
exacerbated by reduced range and increasingly isolated populations 
(Butler 2002a; b, p. 28). If these trends continue, further significant 
declines in total spectaclecase and sheepnose population size and 
consequent reduction in long-term viability may soon become apparent.
    Various exotic species of aquatic organisms are firmly established 
in the range of the spectaclecase and sheepnose. The exotic species 
that poses the most significant threat to the spectaclecase and 
sheepnose is the zebra mussel. The invasion of the zebra mussel poses a 
serious threat to mussel faunas in many regions, and species 
extinctions are expected as a result of its continued spread in the 
eastern United States (Ricciardi et al. 1998, p. 618).
Determination
    We carefully assessed the best scientific and commercial data 
available regarding the past, present, and future threats to the 
spectaclecase and sheepnose. Section 3(6) of the Act defines an 
endangered species as ``any species which is in danger of extinction 
throughout all or a significant portion of its range.'' We find that 
the threats presented above under Factor A: The Present or Threatened 
Destruction, Modification, or Curtailment of Its Habitat or Range are 
considered imminent threats of moderate to high magnitude to the 
sheepnose and spectaclecase. Similarly, threats such as climate change, 
temperature alterations, exotic species, and population fragmentation 
and isolation as discussed under Factor E: Other Natural or Manmade 
Factors Affecting Its Continued Existence are considered imminent 
threats of moderate to high magnitude to both species. These isolated 
species have a limited ability to recolonize historically occupied 
stream and river reaches and are vulnerable to natural or human-caused 
changes in their stream and river habitats. Their

[[Page 14946]]

range curtailment, small population size, and isolation make the 
spectaclecase and sheepnose more vulnerable to threats such as 
sedimentation, disturbance of riparian corridors, changes in channel 
morphology, point- and nonpoint-source pollutants, urbanization, and 
introduced species and to stochastic events (for example, chemical 
spills). Threats of predation discussed in Factor C: Disease and 
Predation of this final rule currently represent a nonimminent threat 
of low magnitude, but it could potentially become a significant future 
threat to the spectaclecase and sheepnose due to their small population 
sizes. The magnitude of threats as described under Factor D: The 
Inadequacy of Existing Regulatory Mechanisms may vary from State to 
state, depending on the strength and enforcement of current 
regulations.
    Based on our analysis, we have no information that population 
trends for either of the two species addressed in this final rule will 
improve, nor will the effects of current threats acting on the species 
be ameliorated in the foreseeable future. Therefore, on the basis of 
the best available scientific and commercial data, we are listing the 
spectaclecase and the sheepnose as endangered under the Act. Without 
the protection of the Act, these species are in danger of extinction 
throughout all of their ranges. This could occur within a few years, 
given recurring drought conditions, accidents, or other existing 
threats. Furthermore, because of their curtailed ranges, and immediate 
and ongoing significant threats to each species throughout their entire 
respective ranges, as described above in the five-factor analysis, we 
find that it is unnecessary to analyze whether there are any 
significant portions of ranges for each species that may warrant a 
different determination of status.

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 encourages and 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 required of Federal agencies and the 
prohibitions against take and harm 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, unless such a plan will not promote the 
conservation of the 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 (comprising species experts, Federal and State 
agencies, nongovernmental organizations, and stakeholders) are often 
established to develop recovery plans. When completed, the recovery 
outline, draft recovery plan, and the final recovery plan will be 
available on our Web site (http://www.fws.gov/endangered), or from our 
Rock Island, Illinois, 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, Tribal, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (for example, 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.
    Listing will also require the Service to review any actions on 
Federal lands and activities under Federal jurisdiction that may 
adversely affect the two species; allow State plans to be developed 
under section 6 of the Act; encourage scientific investigations of 
efforts to enhance the propagation or survival of the animals under 
section 10(a)(1)(A) of the Act; and promote habitat conservation plans 
on non-Federal lands and activities under section 10(a)(1)(B) of the 
Act.
    Section 7(a) of the Act, as amended, 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. Federal agencies are required to confer with us informally on 
any action that is likely to jeopardize the continued existence of a 
proposed species. Section 7(a)(4) 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) 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 adversely affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with the 
Service.
    Federal activities that may affect the sheepnose and spectaclecase 
include, but are not limited to, the funding of, carrying out of, or 
the issuance of permits for reservoir construction, natural gas 
extraction, stream alterations, discharges, wastewater facility 
development, water withdrawal projects, pesticide registration, mining, 
and road and bridge construction.

Jeopardy Standard

    Prior to and following listing and designation of critical habitat, 
if prudent and determinable, the Service applies an analytical 
framework for jeopardy analyses that relies heavily on the importance 
of core area populations to the survival and recovery of the species. 
The section 7(a)(2) analysis is focused not only on these populations 
but also

[[Page 14947]]

on the habitat conditions necessary to support them.
    The jeopardy analysis usually expresses the survival and recovery 
needs of the species in a qualitative fashion without making 
distinctions between what is necessary for survival and what is 
necessary for recovery. Generally, if a proposed Federal action is 
incompatible with the viability of the affected core area 
populations(s), inclusive of associated habitat conditions, a jeopardy 
finding is considered to be warranted, because of the relationship of 
each core area population to the survival and recovery of the species 
as a whole.

Section 9 Take

    Section 9(a)(2) of the Act, and its implementing regulations found 
at 50 CFR 17.21, set forth a series of general prohibitions and 
exceptions that apply to all endangered wildlife. These prohibitions, 
in part, 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, or collect, or to attempt any of these), import or 
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. It also is illegal to knowingly possess, sell, 
deliver, carry, transport, or ship any 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 wildlife species under certain circumstances. 
Regulations governing permits are at 50 CFR 17.22 for endangered 
species. Such permits are available for scientific purposes, to enhance 
the propagation or survival of the species, or for incidental take in 
connection with otherwise lawful activities.
    Our policy, as published in the Federal Register on July 1, 1994 
(59 FR 34272), is to identify, to the maximum extent practicable, those 
activities that would or would not likely constitute a violation of 
section 9 of the Act. The intent of this policy is to increase public 
awareness as to the potential effects of this final listing on future 
and ongoing activities within a species' range. We believe that the 
following activities are unlikely to result in a violation of section 
9:
    (1) Existing discharges into waters supporting these species, 
provided these activities are carried out in accordance with existing 
regulations and permit requirements (for example, activities subject to 
sections 402, 404, and 405 of the Clean Water Act and discharges 
regulated under the National Pollutant Discharge Elimination System).
    (2) Actions that may affect the spectaclecase or sheepnose and are 
authorized, funded, or carried out by a Federal agency when the action 
is conducted in accordance with any reasonable and prudent measures we 
have specified in accordance with section 7 of the Act.
    (3) Development and construction activities designed and 
implemented under Federal, State, and local water quality regulations 
and implemented using approved best management practices.
    (4) Existing recreational activities, such as swimming, wading, 
canoeing, and fishing, that are in accordance with State and local 
regulations, provided that if a spectaclecase or sheepnose is 
collected, it is immediately released, unharmed.
    Activities that we believe could potentially result in take of 
spectaclecase or sheepnose include but are not limited to:
    (1) Illegal collection or capture of the species;
    (2) Unlawful destruction or alteration of the species' occupied 
habitat (for example, unpermitted instream dredging, channelization, or 
discharge of fill material);
    (3) Violation of any discharge or water withdrawal permit within 
the species' occupied range; and
    (4) Illegal discharge or dumping of toxic chemicals or other 
pollutants into waters supporting spectaclecase or sheepnose.
    We will review other activities not identified above on a case-by-
case basis to determine whether they are likely to result in a 
violation of section 9 of the Act. We do not consider these lists to be 
exhaustive and provide them as information to the public.
    You should direct questions regarding whether specific activities 
may constitute a future violation of section 9 to the Field Supervisor 
of the Service's Rock Island, Illinois Ecological Services Field Office 
(see FOR FURTHER INFORMATION CONTACT section). You may request copies 
of the regulations regarding listed wildlife from and address questions 
about prohibitions and permits to the U.S. Fish and Wildlife Service, 
Ecological Services Division, 5600 American Boulevard West, Suite 990, 
Bloomington, MN 55437 (Phone (612) 713-5350; Fax (612) 713-5292).

Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (i) The specific areas within the geographical area occupied by a 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (I) essential to the conservation of the species, and
    (II) that may require special management considerations or 
protection; and
    (ii) specific areas outside the geographical area occupied by a 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.

Conservation is defined in section 3 of the Act as the use of all 
methods and procedures needed to bring the species to the point at 
which listing under the Act is no longer necessary.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against Federal agencies carrying out, funding, 
or authorizing the destruction or adverse modification of critical 
habitat. Section 7(a)(2) requires consultation on Federal actions that 
may affect critical habitat. The designation of critical habitat does 
not affect land ownership or establish a refuge, wilderness, reserve, 
preserve, or other conservation area. Such designation does not allow 
the government or public to access private lands. Such designation does 
not require implementation of restoration, recovery, or enhancement 
measures by non-Federal landowners. Where a landowner seeks or requests 
Federal agency funding or authorization for an action that may affect a 
listed species or critical habitat, the consultation requirements of 
section 7(a)(2) of the Act would apply, but even in the event of a 
destruction or adverse modification finding, the obligation of the 
Federal action agency and the applicant is not to restore or recover 
the species, but to implement reasonable and prudent alternatives to 
avoid destruction or adverse modification of critical habitat.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, we designate critical habitat at the time the 
species is determined to be endangered or threatened. Our regulations 
(50 CFR 424.12(a)(1)) state that the designation of critical habitat is 
not prudent when

[[Page 14948]]

one or both of the following situations exist: (1) The species is 
threatened by taking or other human activity, and identification of 
critical habitat can be expected to increase the degree of threat to 
the species, or (2) such designation of critical habitat would not be 
beneficial to the species.
    There is currently no imminent threat of take attributed to 
collection or vandalism under Factor B (overutilization for commercial, 
recreational, scientific, or educational purposes) for sheepnose and 
spectaclecase, and identification of critical habitat is not expected 
to initiate such a threat. In the absence of finding that the 
designation of critical habitat would increase threats to a species, if 
there are any benefits to a critical habitat designation, then a 
prudent finding is warranted. The potential benefits include: (1) 
Triggering consultation under section 7(a)(2) of the Act, in new areas 
for actions in which there may be a Federal nexus where it would not 
otherwise occur because the species may not be present; (2) focusing 
conservation activities on the most essential habitat features and 
areas; (3) increasing awareness of important habitat areas among State 
or county governments or private entities; and (4) preventing 
inadvertent harm to the species.
    Critical habitat designation includes the identification of the 
physical and biological features of the habitat essential to the 
conservation of each species that may require special management and 
protection. As such, these designations will provide useful information 
to individuals, local and State governments, and other entities engaged 
in activities or long-range planning that may affect areas essential to 
the conservation of the species. Conservation of the spectaclecase and 
sheepnose and essential features of their habitats will require habitat 
management, protection, and restoration, which will be facilitated by 
disseminating information on the locations and the key physical and 
biological features of those habitats. In the case of spectaclecase and 
sheepnose, these aspects of critical habitat designation would 
potentially benefit the conservation of the species. Therefore, since 
we have determined that the designation of critical habitat will not 
likely increase the degree of threat to these species and may provide 
some measure of benefit, we find that designation of critical habitat 
is prudent for the spectaclecase and sheepnose.

Primary Constituent Elements

    In accordance with sections 3(5)(A)(i) and 4(b)(1)(A) of the Act 
and regulations at 50 CFR 424.12, in determining which areas to propose 
as critical habitat, we must consider those physical and biological 
features--primary constituent elements in the necessary and appropriate 
quantity and spatial arrangement--essential to the conservation of the 
species. We must also consider those areas essential to the 
conservation of the species that are outside the geographical area 
occupied by the species. Primary constituent elements include, but are 
not limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, and rearing (or development) 
of offspring; and
    (5) Habitats that are protected from disturbance or are 
representative of the historical, geographical, and ecological 
distribution of a species.
    We are currently unable to identify the primary constituent 
elements for spectaclecase and sheepnose because information on the 
physical and biological features that are considered essential to the 
conservation of these species is not known at this time. The apparent 
poor viability of the species' occurrences observed in recent years 
indicates that current conditions are not sufficient to meet the basic 
biological requirements of these species in many rivers. Since 
spectaclecase and sheepnose have not been observed for decades in many 
of their historical locations, and much of the habitat in which they 
still persist has been drastically altered, the optimal conditions that 
would provide the biological or ecological requisites of these species 
are not known. Although we can surmise that habitat degradation from a 
variety of factors has contributed to the decline of these species, we 
do not know specifically what essential physical or biological features 
of that habitat are currently lacking for spectaclecase and sheepnose.
    Key features of the basic life history, ecology, reproductive 
biology, and habitat requirements of most mussels, including 
spectaclecase and sheepnose, are unknown. Species-specific ecological 
requirements have not been determined (for example, minimum water flow 
and effects of particular pollutants). Population dynamics, such as 
species' interactions and community structure, population trends, and 
population size and age class structure necessary to maintain a long-
term viability, have not been determined for these species. Basics of 
reproductive biology for these species are unknown, such as age and 
size at earliest maturity, reproductive longevity, and the level of 
recruitment needed for species survival and long-term viability. Of 
particular concern to the spectaclecase is the lack of known host(s) 
species essential for glochidia survival and reproductive success. 
Similarly, although recent laboratory studies have produced successful 
transformation of sheepnose glochidia on a few fish species, many 
questions remain concerning the natural interactions between the 
sheepnose and its known hosts. Because the host(s) for spectaclecase is 
unknown and little is known about the sheepnose hosts, there is a 
degree of uncertainty at this time as to which specific areas might be 
essential to the conservation of these species (for example, the 
host(s)'s biological needs and population sizes necessary to support 
mussel reproduction and population viability) and thus meet a key 
aspect of the definition of critical habitat. As we are unable to 
identify many physical and biological features essential to the 
conservation of spectaclecase and sheepnose, we are unable to identify 
areas that contain these features. Therefore, although we have 
determined that the designation of critical habitat is prudent for 
spectaclecase and sheepnose, because the biological and physical 
requirements of these species are not sufficiently known, we find that 
critical habitat for spectaclecase and sheepnose is not determinable at 
this time.

Required Determinations

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain any new collections of information that 
require approval by the Office of Management and Budget (OMB) under the 
Paperwork Reduction Act. The rule will not impose new recordkeeping or 
reporting requirements on State or local governments, individuals, 
businesses, or organizations. An agency may not conduct or sponsor, and 
a person is not required to respond to, a collection of information 
unless it displays a currently valid OMB control number.

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the

[[Page 14949]]

National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), 
need not be prepared in connection with regulations pursuant to section 
4(a) of the 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 rule is available 
on the Internet at http://www.regulations.gov or upon request from the 
Field Supervisor, Rock Island, Illinois, Ecological Services Field 
Office (see FOR FURTHER INFORMATION CONTACT).

Authors

    The primary authors of this rule are the staff members of the 
Service's Rock Island and Twin Cities Field Offices (see FOR FURTHER 
INFORMATION CONTACT).

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--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.


0
2. Amend Sec.  17.11(h) by adding entries for ``Sheepnose'' and 
``Spectaclecase'' in alphabetical order under Clams to the List of 
Endangered and Threatened Wildlife, as follows:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                           Historical range      endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
              Clams
 
                                                                      * * * * * * *
Sheepnose........................  Plethobasus cyphyus.  U.S.A. (AL, IL, IN,  NA.................  E               ...........           NA           NA
                                                          IA, KY, MN, MS,
                                                          MO, OH, PA, TN,
                                                          VA, WV, WI).
 
                                                                      * * * * * * *
Spectaclecase....................  Cumberlandia          U.S.A. (AL, AR, IL,  NA.................  E               ...........           NA           NA
                                    monodonta.            IN, IA, KS, KY,
                                                          MN, MO, OH, TN,
                                                          VA, WV, WI).
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *

    Dated: February 28, 2012.
Daniel M. Ashe,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2012-5603 Filed 3-12-12; 8:45 am]
BILLING CODE 4310-55-P