14914 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Rules and Regulations 

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. 

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 peglike 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 


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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 suspensionfeed, 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 


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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 wildcollected 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 evenaged 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 


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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 post1990 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. 


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TABLE 1—SPECTACLECASE STATUS IN ALL STREAMS OF HISTORICAL OR CURRENT OCCURRENCE

River basin Stream Current 

status 

Date of last 

live or fresh 

dead observation 

Comments 

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 River ................ Extirpated .... Unknown ..... Relic shell 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 River ..................... Extirpated .... Unknown ..... Relic shell 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 


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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 lengthfrequency 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 


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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, 


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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 westcentral 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 severalyear 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 


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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. Bo ̈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 


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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

River Basin Stream Current 

status 

Date of last 

live or fresh 

dead observation 

Comments 

Upper Mississippi River ................... Mississippi River .............................. Declining ..... 2010. 

Minnesota River ............................... Extirpated .... ∼1944. 

St. Croix River ................................. Extirpated .... 1988. 

Chippewa/Flambeau River .............. Stable .......... 2008. 

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. 


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TABLE 2—SHEEPNOSE STATUS AT HISTORICAL LOCATIONS—Continued 

River Basin Stream Current 

status 

Date of last 

live or fresh 

dead observation 

Comments 

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 Michigan (I and M) 

Canal.

Extirpated .... ? 

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 Gasconade River ......... Unknown ..... 1999 ............ Represented by 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 River ................... Extirpated .... 1973. 

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 River .................... Extirpated .... 1908 ............ Relic shell 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 River ................. Extirpated .... 1913. 

French Broad River ......................... Extirpated .... 1914. 

Little Pigeon River ........................... Extirpated .... Unknown. 

Little Tennessee River ..................... Extirpated .... Unknown ..... Relic shell collected in 1971. 

Clinch River ..................................... Stable .......... 2006. 

North Fork Clinch River ................... Extirpated .... ∼1921. 

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 River ......................... Declining ..... 2000. 

Big Black River ................................ Extirpated .... Unknown. 


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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 


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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 westcentral 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 


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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 


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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+-yearold 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. 


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(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 largescale 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 


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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 


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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 wavyrayed 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 porewater 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 speciesspecific 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 


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14932 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Rules and Regulations 

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, 


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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, nonpointsource 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. 


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14934 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Rules and Regulations 

(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 


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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 


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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 lowhead 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 preimpoundment 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 


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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 


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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). Sitespecific 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 


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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 newlyreleased 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 


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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 EPAestablished 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 


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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 longterm effects of large-scale and wideranging 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. Bo ̈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 


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population, predation may amplify 

declines in small populations of this 

species. In addition, the potential now 

exists for the black carp 

(Mylopharyngodon piceus), a molluskeating 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 Statespecific 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 


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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 twothirds 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 sizethreshold 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, 


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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 


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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 mid19th 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 


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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 nonpointsource 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 sitespecific 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 nonFederal 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 


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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 


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14948 Federal Register / Vol. 77, No. 49 / Tuesday, March 13, 2012 / Rules and Regulations 

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 


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

■ 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. 

■ 2. Amend § 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: 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 

Species 

Historical range 

Vertebrate 

population 

where endangered or 

threatened 

Status When listed Critical 

habitat 

Special 

rules Common name Scientific name 

*******

CLAMS

* * * * * * * 

Sheepnose ................... Plethobasus cyphyus .. U.S.A. (AL, IL, IN, IA, 

KY, MN, MS, MO, 

OH, PA, TN, VA, 

WV, WI).

NA ............. E NA NA 

* * * * * * * 

Spectaclecase .............. Cumberlandia 

monodonta.

U.S.A. (AL, AR, IL, IN, 

IA, KS, KY, MN, MO, 

OH, TN, VA, WV, 

WI).

NA ............. E NA NA 

* * * * * * * 

* * * * * 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 


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