[Federal Register Volume 66, Number 195 (Tuesday, October 9, 2001)]
[Rules and Regulations]
[Pages 51322-51339]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-24804]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AF57
Endangered and Threatened Wildlife and Plants; Determination of
Endangered Status for the Scaleshell Mussel
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
the scaleshell mussel (Leptodea leptodon) to be an endangered species
under the Endangered Species Act of 1973, as amended (Act). The
scaleshell mussel historically occurred in 55 rivers in 13 states in
the eastern United States. Currently, the species is known to exist in
14 rivers (and may occur in 6 others) within the Mississippi River
Basin in Missouri, Oklahoma, and Arkansas. Its abundance and
distribution have decreased markedly due to habitat loss and adverse
effects associated with water quality degradation, sedimentation,
channelization, sand and gravel mining, dredging, and reservoir
construction.
DATES: This final rule is effective on November 8, 2001.
ADDRESSES: The complete file for this rule is available for inspection,
by appointment, during normal business hours at the Columbia Field
Office, U.S. Fish and Wildlife Service, 608 East Cherry Street, Room
200, Columbia, Missouri 65201.
FOR FURTHER INFORMATION CONTACT: Andy Roberts (at the above address or
telephone 573-876-1911, ext. 110; fax 573-876-1914). TTY users may
contact us through the Federal Relay Service at 1-800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Buchanan (1980), Cummings and Mayer (1992), Oesch (1995), and
Watters (1995) provide descriptions of the scaleshell mussel. The shell
grows to approximately three to ten centimeters (one to four inches) in
length. The shells are elongate, very thin, and compressed. The
anterior (front) end is rounded. In males, the posterior (rear) end is
bluntly pointed. In females, the periostracum (the outside layer or
covering of the shell) forms a wavy, fluted extension of the posterior
end of the shell. The dorsal (top) margin is straight and the ventral
(bottom) margin is gently rounded. Beaks (the raised or domed part of
the dorsal margin of the shell) are small and low, and nearly even with
the hinge line. The beak sculpture is inconspicuously compressed and
consists of four or five double-looped ridges. The periostracum is
smooth, yellowish green or brown, with numerous faint green rays. The
pseudocardinal teeth (the triangular, often serrated, teeth located on
the upper part of the shell) are reduced to a small thickened ridge.
The lateral teeth (the elongated teeth along the hinge line of the
shell) are moderately long with two indistinct teeth occurring in the
left valve (shell) and one fine tooth in the right. The beak cavity (a
cavity located inside the shell that extends into the beak) is very
shallow. The nacre (the interior layer of the shell) is pinkish white
or light purple and highly iridescent.
Life History
The biology of the scaleshell mussel is similar to the biology of
other bivalved mollusks belonging to the family Unionidae. Adult
unionids are filter-feeders, spending their entire lives partially or
completely buried in the stream bottom (Murray and Leonard 1962). The
posterior margin of the shell is usually exposed and the siphons
extended to facilitate feeding. During periods of activity, movement is
accomplished by extending and contracting a single muscular foot
between the valves. Extension of the foot also enables the mussel to
wedge itself into the river bottom. Their food includes detritus
(disintegrated organic material), plankton, and other microorganisms
(Fuller 1974). Some freshwater mussel species are long-lived.
Individuals of many species live more than 10 years and some have been
reported to live over 100 years (Cummings and Mayer 1992).
Unionids have an unusual and complex mode of reproduction, which
includes a brief, obligatory parasitic
[[Page 51323]]
stage on fish. Males release sperm into the water column in the spring,
summer, or early fall, and females using the incurrent water flow draw
in the sperm. Fertilization takes place in the shell of the female.
Fertilized eggs develop into microscopic larvae (glochidia) and are
brooded within special gill chambers of the female. Once the glochidia
are mature, they are expelled into the water where they must quickly
attach to the gills or the fins of an appropriate fish host to complete
development. Following proper host infestation, glochidia transform
into juveniles and excyst (drop off). Juveniles must drop off into
suitable habitat to survive. Host fish specificity varies among
unionids. Some mussel species appear to require a single host species,
while others can transform their glochidia into juvenile mussels on
several fish species. For further information on the life history of
freshwater mussels, see Gordon and Layzer (1989) and Watters (1995).
Mussel biologists know relatively little about the specific life
history requirements of the scaleshell mussel. Baker (1928) surmised
that the scaleshell mussel is a long-term brooder (spawns in fall
months and females brood the larvae in their gills until the following
spring or summer). Glochidia found in the gill chambers in September,
October, November, and March support that conclusion (Gordon 1991). The
scaleshell mussel uses the freshwater drum (Aplodinotus grunniens) as
the fish host for its larvae (Chris Barnhart, Southwest Missouri State
University, pers. comm. 1998). Other species in the genus Leptodea and
a closely related genus Potamilus are also known to use freshwater drum
exclusively as a host (Watters 1994).
Little is known about the life expectancy of the scaleshell mussel.
However, recent collections from Missouri indicate that it is
relatively short-lived compared to other species. A sample of 33 dead
specimens and 2 living individuals collected in 2000 from a Gasconade
River site did not contain any individuals exceeding seven years old
(Chris Barnhart, pers. comm. 2000). Likewise, no individuals over six
years old were observed out of 44 living individuals collected in 1997
from the Meramec Basin (Roberts and Bruenderman 2000). Based on these
collections, it appears that the life expectancy of the scaleshell
mussel may be less than 10 years. In addition, the sex ratio of the
above collections are significantly different from a 50/50 ratio (Chi-
Square Test, P 0.05). The Gasconade collection only contained eight
females (including one living) out of 35 individuals, and the Meramec
Basin collection only contained 15 females out of 44 living
individuals. The reason females appear to be less common than males in
the Gasconade River and Meramec Basin is unknown.
Habitat Characteristics
The scaleshell mussel occurs in medium to large rivers with low to
moderate gradients in a variety of stream habitats. Buchanan (1980,
1994) and Gordon (1991) reported the scaleshell mussel from riffle
areas with substrate consisting of gravel, cobble, boulder, and
occasionally mud or sand. Oesch (1995) considered the scaleshell mussel
a typical riffle species, occurring only in clear, unpolluted water
with good current. Conversely, Call (1900), Goodrich and Van der
Schalie (1944), and Cummings and Mayer (1992) reported collections from
muddy bottoms of medium-sized and large rivers. Roberts and Bruenderman
(2000) collected the scaleshell mussel primarily from mussel beds
(areas with a high concentration of mussels that contain more than one
species) with stable, gravel substrates. The characteristic common to
these sites appears to be a stable stream bed and good water quality.
These habitat observations are consistent with the current distribution
of the scaleshell mussel. The scaleshell mussel is restricted to rivers
that have maintained relatively good water quality (Oesch 1995) and to
river stretches with stable channels (Buchanan 1980, Harris 1992). The
scaleshell mussel is also usually collected in mussel beds in
association with a high diversity of other mussel species.
Distribution and Abundance
The scaleshell mussel historically occurred in 13 states in the
eastern United States. While the scaleshell mussel had a broad
distribution, it appears that it was a rare species locally (Gordon
1991, Oesch 1995, Call 1900). Williams et al. (1993) reported the
historical range as Alabama, Arkansas, Illinois, Indiana, Iowa,
Kentucky, Missouri, Ohio, Oklahoma, South Dakota, Tennessee, and
Wisconsin. Historical records also exist for the Minnesota River,
Minnesota (Clarke 1996). Williams et al. (1993) also listed Michigan
and Mississippi as part of the scaleshell mussel's range, but no valid
records exist in these states. Therefore, its presence cannot be
confirmed (Bob Jones, Mississippi Wildlife Fisheries and Parks, Museum
of Natural Science, pers. comm. 2000; Szymanski 1998). Gordon (1991)
included a portion of the St. Lawrence drainage in describing the
distribution of the scaleshell mussel. However, the specimens that were
the source of the St. Lawrence River record were later identified as
wingless examples of Leptodea fragilis (fragile papershell), which are
often seen in New York (David Strayer, Institute of Ecosystem Studies,
New York, in litt. 1995). Given this and that no other authentic
specimens have been found (David Stansbery, Ohio State Museum, in litt.
1995), the historical occurrence of the species in St. Lawrence Basin
is doubtful.
Within the last 50 years the scaleshell mussel has become
increasingly rare and its range greatly restricted. Historically, the
scaleshell mussel occurred in 55 rivers. Today, the species is known
from only 14 rivers including the Meramec, Bourbeuse, Big, Gasconade,
and Osage Rivers in Missouri; Frog Bayou and the St. Francis, Spring,
South Fork Spring, South Fourche LaFave, and White Rivers in Arkansas;
and the Little, Mountain Fork, and Kiamichi Rivers in Oklahoma. An
additional six rivers (Cossatot, Little Missouri, Saline, and
Strawberry Rivers, and Myatt and Gates Creeks) in Arkansas and Oklahoma
may support the scaleshell mussel, but the existence of the species in
these rivers is uncertain. With the exception of the Meramec,
Bourbeuse, and Gasconade Rivers, all rivers listed as supporting the
scaleshell mussel are based on the collection of a few or a single
individual specimen.
Assessment of the Presumed Health of Individual Populations
For the purposes of this rule, the term ``population'' is used in a
geographical sense and, unless otherwise indicated, is defined as all
individuals living in one river or stream. By using this term we do not
imply that a scaleshell mussel population is currently reproducing or
that it is a distinct genetic unit. Using the term in this way allows
the status, trends, and threats to be discussed separately for each
river where the scaleshell mussel occurs, improving the clarity of the
discussion.
Due to the low densities of current scaleshell mussel populations,
ascertaining status (an assessment of the current existence of a
population) and trends (an assessment of change in a population's
numbers and its probable future condition) is difficult. To facilitate
population comparisons, a single classification system was devised to
evaluate the probable current health of individual populations. The
indicators of (or criteria for) the presumed health of scaleshell
mussel populations are as follows. The
[[Page 51324]]
presumed health of a population is considered ``stable'' if (1) there
is no evidence of significant habitat loss or degradation, and (2)
there has been post-1980 collection of live or fresh dead mussels and,
if surveys were thorough, evidence of recruitment was found. The
presumed health of a population is considered ``declining'' if (1)
habitat is limiting due to its small size, or a significant decrease in
habitat quality or quantity has occurred, (2) there is no evidence of
recruitment despite one or more thorough surveys, or (3) a significant
decline in number of individual mussels has occurred. The presumed
health of a population is considered ``extirpated'' if (1) despite one
or more thorough post-1980 surveys, no scaleshell mussels, or only old
dead shells, have been found, or (2) all known suitable habitat has
been destroyed. The presumed health of a population is considered
``unknown'' if the available information is inadequate to place the
population in one of the above categories. In a few cases, additional
biological information not listed above was used to categorize a
population that otherwise would have been called ``unknown'' or which
appeared to fit into multiple categories.
Based on the above criteria, 14 scaleshell mussel populations are
considered extant. Of these populations, the presumed health of 1 is
thought to be stable and 13 are believed to be declining. Six other
populations may also be extant, but their health is unknown due to lack
of recent collections or surveys. The 14 extant populations and 6
potentially extant populations are listed in Table 1 and included in
the discussions below.
Table 1.--Presumed Population Health of Extant and Potentially Extant
Scaleshell Mussel Populations. S = stable, D = declining, UK = unknown
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Population Presumed health
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Big (MO)................................... D
Bourbeuse (MO)............................. D
Cossatot (AR).............................. UK
Frog Bayou (AR)............................ D
Gates Creek (OK)........................... UK
Gasconade (MO)............................. D
Kiamichi (OK).............................. D
Little Missouri (AR)....................... UK
Little (OK)................................ D
Meramec (MO)............................... D
Mountain Fork (OK)......................... D
Myatt Creek (AR)........................... UK
Osage River (MO)........................... D
St. Francis (AR)........................... D
Saline (AR)................................ UK
South Fork Spring (AR)..................... S
South Fourche LaFave (AR).................. D
Spring River (AR).......................... D
Strawberry (AR)............................ UK
White River (AR)........................... D
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River Basin Specific Discussion of the Scaleshell Mussel Status
Upper Mississippi River Basin
The scaleshell mussel formerly occurred in eight rivers and
tributaries within the upper Mississippi River Basin, including the
Mississippi River in Illinois, Iowa, and Wisconsin; the Minnesota River
in Minnesota; Burdett's Slough in Iowa; the Iowa and Cedar Rivers in
Iowa; and the Illinois, Sangamon, and Pecatonica Rivers in Illinois.
However, the scaleshell mussel has not been found for more than 50
years in the upper Mississippi River Basin and is believed extirpated
from that basin (Kevin Cummings, Illinois Natural History Survey, in
litt. 1994).
Middle Mississippi River Basin
Historically, the scaleshell mussel occurred in 26 rivers and
tributaries within the middle Mississippi River Basin including the
Kaskaskia River in Illinois; the mainstem Ohio River in Kentucky and
Ohio; the Wabash River in Illinois and Indiana; the White River and
Sugar Creek in Indiana; the Green and Licking Rivers in Kentucky; the
Scioto, St. Mary's, and East Fork Little Miami Rivers in Ohio; the
Cumberland River in Kentucky and Tennessee; Beaver Creek in Kentucky;
Caney Fork in Tennessee; the Tennessee River in Alabama and Tennessee;
the Clinch, Holston, and Duck Rivers in Tennessee; Auxvasse Creek in
Missouri; the Meramec, Bourbeuse, South Grand, Gasconade, Big, Osage,
and Big Piney Rivers in Missouri; and the mainstem Missouri River in
South Dakota and Missouri. The scaleshell mussel has been extirpated
from most of the middle Mississippi River Basin. Currently, the
scaleshell mussel is extant in five rivers within the Meramec River
basin and tributaries of the Missouri River drainages in Missouri.
Ohio River Drainage--The scaleshell mussel has been extirpated from
the entire Ohio River system. The most recent collection date from the
Ohio River Basin is 1964 from the Greene River (Wayne Davis, Kentucky
Department of Fish and Wildlife, in litt. 1994). All other records are
pre-1950 (Kevin Cummings, in litt. 1994; Catherine Gremillion-Smith,
Indiana Department of Natural Resources, in litt. 1994; Ron Cicerello,
Kentucky Department of Fish and Wildlife, in litt., 1994; Paul
Parmelee, University of Tennessee, pers. comm. 1995).
Meramec River Basin (Missouri)--In 1979, Buchanan surveyed for
mussels at 198 sites within the Meramec River Basin (Buchanan 1980). Of
these sites, 14 had evidence of live or dead scaleshell mussels. Seven
of the 14 sites were in the lower 180 kilometers (km) (112 miles (mi))
of the Meramec River, five in the lower 87 km (54 mi) of the Bourbeuse
River, and two in the lower 16 km (10 mi) of the Big River. Buchanan
found that the species comprised less than 0.1 percent of the 20,589
living mussels he examined in the basin. He collected live scaleshell
mussels at only four sites, three in the Meramec and one in the
Bourbeuse. Although the lower 174 km (108 mi) of the Meramec River had
suitable habitat for many rare species, live scaleshell mussels were
found only in the lower 64 km (40 mi) (Buchanan 1980). Both the
Bourbeuse and Big Rivers had lower species diversity and less suitable
habitat than the Meramec River. Suitable habitat occurs only in the
lower 87 km (54 mi) of the Bourbeuse River and lower 16 km (10 mi) of
the Big River (Buchanan 1980).
The Missouri Department of Conservation (MDC) sampled 78 sites in
an intensive resurvey of the Meramec River basin in 1997 (Roberts and
Bruenderman 2000). Similar to Buchanan's findings (1980), scaleshell
mussels represented only 0.4 percent of the living mussels. Live
specimens were collected from the mainstem Meramec River (34 specimens
from 9 sites), the Bourbeuse River (10 specimens from 5 sites), and the
Big River (2 specimens from 1 site). In addition to the nine sites
surveyed by Buchanan (1979), new sites were included in the 1997
survey. Living or dead scaleshell mussels were found at four of the
five sites in the Meramec River and two of the four sites in the
Bourbeuse River. The three sites where the presence of scaleshell
mussels was not reconfirmed no longer support suitable mussel habitat
due to stream bed degradation. Other species that were found in mussel
beds at those sites in the earlier surveys were no longer present in
1997. Although portions of the Meramec River basin continue to provide
suitable habitat, mussel species diversity and abundance have declined
noticeably since 1980 and
[[Page 51325]]
significant losses of mussel habitat have occurred (Roberts and
Bruenderman 2000).
The number of scaleshell mussel specimens the MDC collected in 1997
is greater than that reported by Buchanan's study (Buchanan 1980);
however, the small number of specimens collected, especially from the
Bourbeuse and Big Rivers, indicates that the long-term viability of
these populations is tenuous. Moreover, the long-term persistence of
populations in the Meramec Basin is in question because of the limited
availability of mussel habitat and the loss of mussel beds since 1980
from bank and channel degradation, sedimentation, and eutrophication
(excessive fertilization caused by pollution of plant nutrients)
(Roberts and Bruenderman 2000; Alan Buchanan, MDC, in litt. 1997; Sue
Bruenderman, MDC, pers. comm. 1998).
Missouri River drainage (South Dakota and Missouri)--Within the
Missouri River drainage, Buchanan (1980, 1994) and Oesch (1995)
reported scaleshell mussels from the Missouri, Gasconade, Big Piney,
South Grand, Osage Rivers, and Auxvasse Creek. The last collection of
scaleshell mussels from Auxvasse Creek was in the late 1960s (Alan
Buchanan, in litt. 1997). Similarly, the last known collection date for
the South Grand is the early 1970s. This collection site is now
inundated by Truman Lake and is unsuitable for the scaleshell mussel
(Alan Buchanan, in litt. 1997). A single, fresh dead specimen was
collected from Big Piney River in 1981 (Sue Bruenderman, in litt.
1998). However, the scaleshell mussel has not been found in recent
surveys of this river. Between 1994 and 1996, 70 sites were sampled in
the Big Piney River from the mouth to the headwaters. While 3,331
mussels of 26 species were collected, no evidence of scaleshell mussels
were found (Janet Sternberg, MDC, pers. comm. 2000). Another survey was
conducted in 1998, in which 10 sites were sampled between river miles
53.6 and 96.0. Over 1,000 living mussels were collected representing 15
species, but no living or dead scaleshell mussels were found (Sue
Bruenderman, pers. comm. 2000).
Only two records (both single dead shells) of scaleshell mussels
exist for the mainstem of the Missouri River. In 1981 and 1982, the
Missouri River was surveyed from Santee to Omaha, Nebraska (Hoke 1983).
A single fresh dead shell was found during this study just below
Gavin's Point Dam, South Dakota. This occurrence represents the
westernmost record of the scaleshell mussel in North America. However,
this species has not been found in subsequent surveys on the Missouri
River just below Gavin's Point dam. In 1995, Clarke (1996) found no
evidence of scaleshell mussels in a survey conducted from Gavin's Point
Dam to 48 river km (30 mi) downstream. However, high water conditions
limited Clark's search efforts, and only 10 individual mussels were
found. In 1999, the Omaha District of the U.S. Army Corps of Engineers
(Corps) funded a mussel survey between Gavin's Point Dam and Ponca,
Nebraska, a distance of 96 river km (60 mi). In all, 355 live and 1,709
dead individual mussels were collected representing 16 species, but no
living or dead scaleshell mussels were found (Candace M. Gordon, Corps,
Omaha District, in litt. 2000). The second scaleshell mussel record
from the mainstem of the Missouri River is a single fresh dead
individual that was collected in 1990 from Gasconade County, Missouri.
This specimen was found during an extensive survey conducted from
Gavin's Point Dam to St. Louis (Hoke 2000). However, the site of this
collection was subsequently destroyed.
Since no living scaleshell mussel has been found in the Missouri
River, its habitat cannot be determined. However, both dead shells were
collected from areas shielded from the main flow of the river in
relatively stable, sandy bottoms with moderate current (Hoke 2000).
Hoke (2000) described scaleshell mussel as ``extremely rare'' and its
habitat ``very uncommon * * * and existing in only widely separated
locals'' in the Missouri River. Based on the criteria used to assign
presumed health to scaleshell mussel populations (Table 1), we consider
this potential population to be extirpated at this time. Of the two
known Missouri River records for scaleshell mussel, one locality has
been destroyed and recent surveys have not found any evidence of this
species at or in the vicinity of the other site. Further, no other
scaleshell mussel specimens were found during Hoke's survey from
Gavin's Point Dam to St. Louis. More information is needed on the
existence of the scaleshell mussel and its habitat in the Missouri
River. Furthermore, more information is needed on the location of
sampling sites, distribution and habitat use of mussels, etc. from
Hoke's survey work on the Missouri River, which is unavailable at this
time.
Buchanan (1994) surveyed the lower 137 km (85 mi) of the Gasconade
River, and documented 36 species of freshwater mussels. He collected
scaleshell mussel specimens at eight sites between river miles 6.0 and
57.7. Buchanan found only dead shells at two sites and eight live
specimens from the remaining six sites. Overall, scaleshell mussels
comprised less than 0.1 percent of the mussels collected. In 1998-99,
the Gasconade River was surveyed at 46 sites from mile 92.0 to 256.0.
At sites where scaleshell mussels were collected, living individuals
represented less than 0.5 percent of the total number of mussels found.
A total of 12 living scaleshell mussels were found at 9 sites, and dead
shells were found at an additional 10 sites between river miles 92.0
and 230.3 (Sue Bruenderman, pers. comm. 2000).
A scaleshell mussel has recently been discovered in the lower Osage
River in Osage County, Missouri. On July 16, 2001, one live male
specimen was found at river mile 20 (Heidi Dunn, pers. comm.). This
individual was found during a mussel survey that is currently underway
in the lower 80 miles of the Osage River and its tributaries. To date,
33 sites have been surveyed including 24 in the mainstem. A total of
3,904 living mussels have been found representing 29 living species. No
other evidence of scaleshell mussels were found during the survey, but
more intensive sampling is planned for these same sites in the near
future.
Until this recent discovery, the scaleshell mussel had never been
reported from the Osage system in past surveys. Utterback (1917) found
34 species in the basin. No other information is available because his
notes and collections have since been lost. Oesch (1995) collected
mussels in the 1970s at a number of sites in the basin and reported 39
species. In 1980, a detailed study of mussel distribution was conducted
by Grace and Buchanan (1981) of the Lower 80 miles of the Osage River
and two tributaries below Bagnell Dam. A total of 43 sites were
surveyed and 21,593 living mussels were found representing 36 species.
No evidence of scaleshell mussels was found in any of these surveys.
This new record of the scaleshell mussel does not significantly
increase its range or lessen its risk of extinction. Similar to other
records for the species, the one individual found indicates that a
small population is present. No other evidence of the species was found
during the 2001 survey. If a significant population of scaleshell
mussels existed in the Osage River, dead shells would have been found.
This is because dead shells accumulate over time, which makes them
easier to detect than live specimens. Additionally, there are
significant threats to scaleshell mussel in the Osage River from the
operation of Bagnell Dam and instream gravel mining. Due to these
habitat conditions, we categorized the Osage River
[[Page 51326]]
scaleshell mussel population's presumed health as declining.
Middle Mississippi River Basin summary--Of the 26 rivers and
tributaries in the middle Mississippi River Basin that historically
supported scaleshell mussels, the species is still present in 5
including the Meramec, Bourbeuse, Big, Osage, and Gasconade Rivers. The
presumed health of all of these populations is thought to be declining.
Lower Mississippi River Basin
The scaleshell mussel historically occupied 21 rivers and
tributaries in the lower Mississippi River Basin. These include the St.
Francis, White, James, Spring, Little Missouri, Middle Fork Little Red,
Saline (of the Ouachita River), Ouachita, Cossatot, Saline (of the
Little River), South Fourche LaFave, Mulberry, and Strawberry Rivers in
Arkansas; South Fork Spring, Frog Bayou, and Myatt Creek in Arkansas;
Poteau, Little, and Kiamichi Rivers in Oklahoma; and Gates Creek and
Mountain Fork in Oklahoma. These rivers are organized and discussed
below according to drainage (St. Francis, White, Arkansas, and Red
River drainages).
St. Francis River drainage (Arkansas)--Bates and Dennis (1983),
Clarke (1985), and Ahlstedt and Jenkinson (1987) conducted mussel
surveys on the St. Francis River in Arkansas and Missouri. Of these
surveys, scaleshell mussels were only documented from two sites, both
of which are single-specimen records (Clarke 1985). Records of dead
shells of various species indicate that at one time freshwater mussels
occurred throughout the river (Bates and Dennis 1983). Bates and Dennis
(1983) determined that of the 54 sites sampled, 15 were productive, 10
marginal, and 29 had either no shells or dead specimens only;
scaleshell mussels were not documented at any of the 54 sites. They
identified 77 km (48 mi.) of habitat generally suitable for mussels:
Wappapello Dam to Mingo Ditch, Missouri; Parkin to Madison, Arkansas;
and Marianna to the confluence with the Mississippi River at Helena,
Arkansas. They indicated that the remaining portions of the river were
no longer suitable for mussels. If the scaleshell mussel is extant in
the St. Francis River, it is restricted to the few patches of suitable
habitat.
White River drainage (Arkansas)--Clarke (1996) noted a 1902
collection of a single specimen from the White River near Garfield,
Arkansas. A late 1970s survey of the White River between Beaver
Reservoir and its headwaters failed to relocate live or dead scaleshell
mussel individuals. However, in 1999, a single live specimen was
collected from the White River near Newport by John Harris (John
Harris, Arkansas Department of Transportation, pers. comm. 2000).
Navigation maintenance activities have relegated the mussel fauna to a
few refugial sites (Bates and Dennis 1983). Specimens have not been
collected from the James River, a tributary of the White River, since
before 1950 (Clarke 1996).
An eight-mile section of the Spring River in Arkansas supports a
diverse assemblage of freshwater mussels (Gordon et al. 1984, Arkansas
Highway and Transportation Dept 1984, Miller and Hartfield 1986). The
collections from this river total eight scaleshell mussel specimens
(Kevin Cummings, in litt. 1994; Clarke 1996, Arkansas State Highway and
Transportation Department, 1984). Gordon et al. (1984) surveyed the
river and reported suitable mussel habitat between river miles 3.2 and
11.0, although species richness below river mile 9 had declined
markedly compared to past surveys. Gordon et al. (1984), as well as
Miller and Hartfield (1986), reported that the lower 5.0 km (3.0 mi) of
river were completely depleted of mussels and contained no suitable
habitat. Harris did not find scaleshell mussels in a 1993 survey of the
Spring River (John Harris, in litt. 1997).
Scaleshell mussels were collected from the South Fork of the Spring
River in 1983 and 1990. During the 1983 survey, Harris (in litt. 1997)
collected four specimens near Saddle, Arkansas, and one specimen and
one valve north of Hunt, Arkansas. During a subsequent visit in 1990,
Harris collected young adults (Harris, pers. comm. 1995). Although
juveniles were not found, the presence of young adults suggests that
reproduction recently occurred.
Records of scaleshell mussels from the Strawberry River and the
Myatt Creek are based on single specimen collections, both made in 1996
(John Harris, in litt. 1997). Harris collected a live specimen from the
Strawberry River near the confluence with Clayton Creek in Lawrence
County. He also collected a single relict (a weathered shell that has
been dead a long period of time) specimen from Myatt Creek in Fulton
County (John Harris, in litt. 1997). Comprehensive surveys have not
been conducted in these rivers since 1996.
The historical locality (near Shirley, Van Buren County, Arkansas)
where a single scaleshell mussel specimen was collected from the Middle
Fork of the Little Red River no longer provides mussel habitat. Clarke
(1987) stated that suitable mussel habitat was restricted to a 9.6 km
(6.0 mi) stretch from the confluence of Tick Creek upstream to the
mouth of Meadow Creek.
Arkansas River drainage (Oklahoma and Arkansas)--The scaleshell
mussel has been collected from the following streams from the Arkansas
River drainage: Poteau River in Oklahoma (Gordon 1991), Frog Bayou in
Arkansas (Harris and Gordon 1987), and the South Fourche LaFave and
Mulberry Rivers in Arkansas (Gordon 1991; Harris 1992). A single
scaleshell mussel specimen was collected in the Poteau River (Gordon
1980). However, it has not been documented in subsequent surveys of
this river (Branson 1984; Harris 1994). The existence of scaleshell
mussels in Poteau River is doubtful.
Gordon (1980) collected two scaleshell mussel specimens from Frog
Bayou. Beaver Reservoir now inundates one of the Frog Bayou collection
sites. The most recent collection was a fresh dead individual during a
1979 survey (Gordon 1980). Gordon noted that stream bank bulldozing
upstream recently disturbed this site and other nearby sites. He also
reported in-stream gravel mining activities at several sites. Within
Frog Bayou, potential habitat is restricted to the area between Rudy
and the confluence of the Arkansas River. Above Rudy, two reservoirs
impact the river; one near Maddux Spring and the other at Mountainburg.
Live mussels have not been found at the confluence of the Arkansas
River, likely due to dredging activities (Gordon 1980). Although the
current status of the scaleshell mussel in Frog Bayou is uncertain, any
remaining individuals are in potential jeopardy due to limited habitat
and in-stream mining activities.
The only scaleshell mussel record from the South Fourche LaFave
River is based on a single live specimen found in 1991 (Harris 1992).
An 86-acre reservoir is approved for construction on Bear Creek
approximately six miles upstream from this site. However, the effect of
this impoundment on scaleshell mussels is uncertain. The potential for
discovering additional scaleshell mussel sites in this river is
unlikely due to the limited availability of suitable substrate.
Similarly, other major tributaries of the South Fourche LaFave River
provide little mussel habitat. Like Frog Bayou, the persistence of
scaleshell mussels in this river is in doubt.
Although Gordon (1991) reported scaleshell mussels from the
Mulberry River, documentation is lacking. Recent surveys did not find
the species in the Mulberry River (Craig Hilborne, U.S. Forest Service,
pers. comm. 1995;
[[Page 51327]]
Stoeckel et al. 1995). The existence of scaleshell mussels in the
Mulberry River is unlikely.
Red River drainage (Oklahoma and Arkansas)--The scaleshell mussel
has been documented from the following streams in the Red River
drainage: the Kiamichi River, Gates Creek, Little River, Mountain Fork;
and the Cossatot, Ouachita, Little Missouri, and Saline Rivers. Isley
(1925) first collected scaleshell mussels from the Kiamichi River in
1925. Based on his account, the Kiamichi River historically supported a
diverse and abundant mussel fauna. He collected 36 scaleshell mussel
specimens at one of 22 stations visited. A single specimen was also
collected from Gates Creek, a tributary of the Kiamichi River, by
Valentine and Stansbery (1971). As recently as 1987, Clarke described
the Kiamichi River as ``in remarkably good condition'' and a ``faunal
treasure'' (Clarke 1987). However, despite extensive searches of the
Kiamichi River over the last 11 years, only a single fresh dead shell
of scaleshell mussel (in 1987) has been collected (Caryn Vaughn,
Oklahoma Biological Survey, pers. comm. 1997; Charles Mather,
University of Science and Arts of Oklahoma, in litt. 1984 and 1995).
Vaughn (pers. comm. 1997) failed to find even a dead shell during three
years (1993-1996) of surveys in the Red River Basin. However, the
mussel habitat in the Kiamichi River is in relatively good condition
above the Hugo Reservoir (Clarke 1987) and may still support a remnant
population of scaleshell mussels.
Although there is no evidence of scaleshell mussels persisting in
the Little River, healthy mussel beds exist above the Pine Creek
Reservoir (Caryn Vaughn, in litt. 1997). Below Pine Creek Reservoir,
the mussel fauna is severely depleted but recovers with increasing
distance from the impoundment (Caryn Vaughn, in litt. 1997). Although
scaleshell mussels have not been documented during extensive surveys
throughout the length of the Little River, suitable habitat remains and
the species may persist (Caryn Vaughn, in litt. 1997). However, the
discharge of reservoir water from Pine Creek and periodic discharge of
pollution from Rolling Fork Creek may seriously impact any remaining
viable scaleshell mussel populations and prohibit any future
recolonization (Clarke 1987). Valentine and Stansbery (1971) reported a
single specimen from Mountain Fork. Clarke (1987) hypothesized that,
based on the presence of mussels at the confluence of Mountain Fork and
beyond the Arkansas border, damage to Mountain Fork from the Broken Bow
Reservoir has not occurred. However, Vaughn (in litt. 1997) indicated
that these areas have been severely depleted with most no longer
containing live mussels.
If scaleshell mussels still occur in the Red River drainage in
Oklahoma, extant populations are probably small and are likely
restricted to isolated areas of suitable habitat in the Kiamichi and
Mountain Fork Rivers. Given the extensive survey effort over the last
decade, long-term survival of the scaleshell mussel in Oklahoma is
doubtful.
Harris collected single scaleshell mussel specimens from the
Cossatot and Saline Rivers in Arkansas in 1983 (John Harris, in litt.
1997) and 1987 (John Harris, pers. comm. 1995), respectively. No other
information is available for either river.
The existence of scaleshell mussels in the Ouachita River and its
two tributaries, the Saline River and Little Missouri River, is
questionable as well. Both the Little Missouri and Saline Rivers
records are based on single specimens. The Saline River specimen was
collected in 1964 (Clarke 1996), and the Little Missouri River
collection record is from 1995 (John Harris, in litt. 1997). Four
undated museum specimens of scaleshell mussels from the Ouachita River
in Arkadelphia, Clark County, Arkansas are listed in Clarke (1996), but
details are unavailable. Based on the few collections and the limited
habitat available, the long-term persistence of scaleshell mussel in
Cossatot, Saline, Little Missouri, and Ouachita Rivers appears
precarious.
Lower Mississippi River Basin summary--Of these 21 rivers and
tributaries in the lower Mississippi River Basin that historically
supported scaleshell mussels, nine, and possibly an additional six,
support the species today. Of these populations, the South Fork Spring
River could possibly be stable; the St. Francis River, Kiamichi River,
Little River, Mountain Fork, Spring River, Frog Bayou, South Fourche
LaFave River, and White River are presumed to be declining; and the
status of the Myatt and Gates Creeks and the Strawberry, Cossatot,
Saline, and Little Missouri Rivers populations are unknown.
Previous Federal Action
We had identified the scaleshell mussel as a Category 2 candidate
species in a notice of review published in the Federal Register on May
22, 1984 (49 FR 21664). The scaleshell mussel remained a Category 2
candidate species in subsequent notices including January 6, 1989 (54
FR 554), November 21, 1991 (56 FR 58804), and November 15, 1994 (59 FR
58982). Prior to 1996, a Category 2 candidate species was one that we
were considering for possible addition to the Federal List of
Endangered and Threatened Wildlife, but for which conclusive data on
biological vulnerability and threats were not available to support a
proposed rule. We discontinued designating Category 2 species in the
February 28, 1996, Notice of Review (61 FR 7596). We now define a
candidate species as a species for which we have on file sufficient
information on biological vulnerability and threats to support issuance
of a proposed rule. We designated the scaleshell mussel as a candidate
species on October 16, 1998.
On August 13, 1999 (64 FR 44171), we published a proposal to list
the scaleshell mussel as an endangered species and opened a 60-day
comment period on the proposal. On November 29, 1999 (64 FR 66600), we
reopened the comment period for 39 days in order to hold a public
hearing. The hearing was held in Jefferson City, Missouri, on December
8, 1999.
Summary of Comments and Recommendations
In the August 13, 1999, proposed rule, and through associated
notifications, we requested all interested parties to submit factual
reports or information that might contribute to the development of a
final rule. We contacted appropriate Federal and State agencies, County
governments, scientific organizations, and interested parties and
requested their comments. We published notices inviting public comment
in the following newspapers in 1999: The Chicago Sun Times, The Chicago
Tribune, The Peoria Journal Star, State Journal-Register, The Journal
Gazette Co., The Indianapolis Star, The Columbia Daily Tribune, The
Kansas City Star, The St. Louis Post-Dispatch, The South Bend Tribune,
The Cedar Rapids Gazette, Quad City Times, The Des Moines Register, The
Cincinnati Post, The Cleveland Plain Dealer,
The Columbus Dispatch, Cuba Free Press, Steelville Star-Crawford
Mirror, Jefferson County Journal, Jefferson County Leader, Jefferson
County News Democrat Journal, Meramec Journal, Jefferson County
Watchman, TriCounty Journal, County Star Journal West, Chesterfield
Journal, Clayton-St. Louis County Watchman, North County Journal-West,
Florissant Valley Reporter, North County Journal-East, North Side
Journal, County Star Journal-East, Concord Call, Mid-County Journal,
Oakville Call, Oakville/Mehlville Journal, St. Louis Countian, South
[[Page 51328]]
County Journal, South County Times, Southwest County Journal, Webster-
Kirkwood Times, West County Journal, Citizen Journal, Webster/Kirkwood
Journal, South County News-Times, Press Journal, New Haven Leader, St.
Clair Missourian, Sullivan Independent-News, Franklin County Watchman,
Union Missourian, Washington Missourian, Bland Courier, Advertiser-
Courier, Gasconade County Republican, Unterrified Democrat, Dixon
Pilot, The Richland Mirror, Fort Leonard Wood Essayons, and The Daily
Guide.
The Service hosted a public hearing (December 8, 1999, in Jefferson
City, Missouri) at the request of Two Rivers Levee and Drainage
Association, Law Offices of John C. Franken, Howard/Cooper County
Regional Port Authority, and 180 private citizens. To accommodate this
request, we reopened the comment period from November 29, 1999, to
January 7, 2000, to allow for consideration of, and to provide an
opportunity for, further comments. A notice of the hearing and
reopening of the comment period was published in the Federal Register
on November 29, 1999 (64 FR 66600), and in legal notices in the
newspapers listed above.
We received 26 letters providing comments and information during
the comment periods. Additionally, six individuals provided oral
statements at the public hearing. We have updated this rule to reflect
any changes in information concerning distribution, status, and threats
since the publication of the proposed rule. All pertinent comments have
been considered in the formulation of this final rule. Written comments
received during the comment periods and written comments and oral
statements presented at the public hearings are addressed in the
following summary. Comments of a similar nature or point are grouped
together (referred to as ``Issues'' for the purpose of this summary)
below, along with the Service's response to each.
Issue 1: One respondent was unsure of what this listing would
accomplish beyond the recovery efforts of other mussel species already
federally listed in Missouri.
Response: This action will extend the Act's protection to this
species. Federal listing results in an increased awareness of this
species' status and its need for conservation attention. It also
provides for opportunities for funding research, management activities,
and conservation actions specifically targeted for this species. In
addition to better funding opportunities, Federal endangered status
encourages scientists and natural resource managers to focus research
and conservation actions specifically for the scaleshell mussel.
There are currently four federally listed mussel species in
Missouri (Missouri Natural Heritage Database 1999). These are the pink
mucket (Lampsilis abrupta), Curtis pearlymussel (Epioblasma florentina
curtisi), Higgins' eye (Lampsilis higginsii), and fat pocketbook
(Potamilus capax). We agree that where overlap of listed mussels
occurs, the prohibitions of the Act will provide little additional
protection of habitat. However, the current range of scaleshell mussel
extends to areas where there are no federally listed species. The Act
will provide protection from further habitat loss and degradation in
these areas.
Issue 2: One respondent was concerned that the public will not know
what impacts this listing will have on activities on private property
until after the recovery plan is completed. The respondent was
referring to potential impacts of recovery actions on private land in
particular.
Response: While recovery plans are not developed until after a
species is listed, there is opportunity for public input in the
recovery planning stage. The purpose of the recovery plan is to set
recovery objectives (goals) and identify the tasks needed to meet those
objectives before a species can be downlisted or delisted. As the draft
recovery plan is announced in the Federal Register, we will solicit
comment from species experts, natural resource managers, and other
interested parties. To ensure broad participation in the review of the
recovery plan, we will notify all interested parties that were
identified during the listing process (for example, those that provided
comments or requested to be on our mailing list).
Although actions that could be affected by the listing were
identified in the proposed rule, we acknowledge that impact upon
private actions cannot be fully assessed until a recovery plan is
developed. However, in ascertaining whether a species warrants Federal
protection under the Act, we may consider only biological factors. In
accordance with 16 U.S.C. sec. 1533(b)(1)(A) and 50 CFR 424.11, listing
decisions are made solely on the basis of the best scientific and
commercial data available. The legislative history of the 1982 Act
amendments states: ``The addition of the word ``solely'' is intended to
remove from the process of the listing or delisting of species any
factor not related to the biological status of the species. The
Committee strongly believes that economic considerations have no
relevance to determinations regarding the status of the species. * *
*'' H.R. Rep. No. 567, Part I, 97th Congress, 2nd Session 20 (1982).
Thus, the impact of listing on private activities, although of great
interest and importance to the public, is not a factor we may consider
in our listing determination.
Issue 3: One respondent questioned whether the range of the
scaleshell mussel, particularly in the Missouri River, is based on
records that were identified correctly. Scaleshell mussels can be
easily confused with the fragile papershell (Leptodea fragilis) or the
pink papershell (Potamilus ohioensis), which are more common and
widespread.
Response: We acknowledge that scaleshell mussels may be confused
with other species by the casual observer. Freshwater mussels are often
difficult to identify by shell shape alone. However, to malacologists
(a person who studies mollusks) and other properly trained biologists,
there are no ambiguities in distinguishing scaleshell mussels from
other species. Female scaleshell mussels are unique and unlikely to be
mistaken with any other species. Females are small, very elongated, and
the posterior edge is ruffled. Male scaleshell mussels can possibly be
confused with other species, particularly the fragile papershell.
However, several external characteristics distinguish male scaleshell
mussels from the fragile papershell, the pink papershell, and other
species. These characteristics include the presence of green rays,
light brown periostracum, pointed posterior end, absence of dorsal
wings, elongated shell, straight dorsal margin, and rounded ventral
margin (Parmalee and Bogan 1998, Oesch 1995, Watters 1995).
While it is possible that a small number of scaleshell mussel
specimens have been misidentified, we are confident that the range of
this species is based on valid specimens because many records are
represented by voucher specimens that are housed in museums. The
identification of these specimens has been verified by expert
malacologists. In particular, the records of scaleshell mussel from the
Missouri River were identified by Dr. David H. Stansbery, who is a
leading authority in North America on freshwater mussel identification
at the Ohio State Museum located at Ohio State University in Columbus,
Ohio.
Issue 4: The proposed rule states that gravel mining has recently
become a more serious threat for scaleshell mussel range-wide because
the Corps' authority to regulate instream gravel mining has been
reduced. One respondent stated that this issue will probably not be
[[Page 51329]]
overlooked by the State agencies. In other words, gravel mining will
probably be regulated by State agencies now that the Corps has less
authority to regulate this activity.
Response: Section 404 of the Clean Water Act of 1972 (CWA) provides
regulations for discharge of dredged and fill materials in surface
waters, including a permit program to ensure that such discharges
comply with other State and Federal environmental regulations. The
Corps is the Federal agency responsible for implementing this section
of the CWA. Until 1997, instream mining was more strictly regulated,
because incidental fallback of material during a dredging action was
considered fill in surface waters, and thus triggered section 404
compliance. Due to a 1997 Federal court decision, however, incidental
fallback of material is no longer considered fill. Consequently, only
activities that result in discharge of fill material greater than
incidental fallback are regulated under section 404 (see factors A and
D under the ``Summary of Factors Affecting the Species'' section for
further information on this issue).
As discussed in Issue 1, federally listed species frequently
coexist with scaleshell mussels. Section 7 of the Act requires all
Federal agencies, including the Corps, to consult with the Service
regarding any action that may adversely affect listed species. Through
this consultation process, the Service identifies conservation
measures, which minimize adverse impacts to listed species. With
incidental fallback no longer requiring a Corps section 404 permit, the
section 7 consultation process is no longer applicable for many
instream gravel mining activities.
Some State agencies have authority to regulate gravel mining within
their state. In Arkansas, instream gravel mining is regulated by the
Arkansas Open-Cut Mining and Land Reclamation Code, which contains
guidelines to reduce impacts (Roell 1999). The Missouri Department of
Natural Resources (MDNR) also has the authority to regulate gravel
mining in Missouri under the Land Reclamation Act. However, their
regulatory authority is limited. First, only commercial operators are
required to obtain a permit to remove gravel from streams and rivers.
City, county, and state operators using their own equipment and private
operations are not required to obtain a permit from MDNR. Also, these
operators are not obligated to comply with permit conditions that are
crucial in avoiding adverse impacts to the stream environment. Second,
MDNR's conditions for gravel mining permits are less stringent than
those required previously by the Corps (Mike Larson, Missouri
Department of Natural Resources, pers. comm. 2000). For example, the
MDNR permit does not prohibit the modification of water conveyance,
limit excavation to unconsolidated areas, require bank and water buffer
strips, or minimize the removal of aquatic and terrestrial vegetation.
All of these factors could adversely affect the scaleshell mussel and
its habitat.
Issue 5: Several respondents are concerned that this listing will
impact activities on private property. One respondent was concerned
that impoundments will be more difficult to construct after the
listing.
Response: This listing will protect scaleshell mussels from take
under section 9 (Prohibited Acts) of the Act. Take is defined by the
Act as ``harass, harm, pursue, hunt, shoot, wound, capture, collect, or
attempt to engage in any such conduct.'' Take is further defined by
regulation to include ``significant habitat modification or degradation
that actually kills or injures wildlife,'' (50 CFR 17.3 ``Harm''). Non-
Federal property owners, such as private landowners, corporations, or
State or local governments, wishing to conduct activities on their land
that might result in the incidental take of scaleshell mussels can
obtain an incidental take permit from the U.S. Fish and Wildlife
Service. Section 10 of the Act provides for the issuance of permits to
conduct otherwise prohibited activities. Through section 10, there is
an opportunity to provide species protection and habitat conservation
for non-Federal development and land use activities that may result in
incidental take of a listed species. For landowners and local
governments, these incidental take permits, and their associated
habitat conservation plans (HCP), provide long-term assurances that
their activities will be in compliance with the requirements of the
Act. Biologically, they provide the Service with a tool to offset the
incidental take of listed species by reconciling species conservation
with economic development. The HCP process allows private development
to proceed while promoting listed species conservation.
The No Surprises policy provides assurances to non-Federal
landowners participating in HCP efforts through the section 10(a)(1)(B)
process. Essentially, landowners are assured that if ``unforeseen
circumstances'' arise, the Services will not require, without the
consent of the permittee, the commitment of additional land, water or
financial compensation or additional restrictions on the use of land,
water, or other natural resources beyond the level otherwise agreed to
in the HCP. The government will honor these assurances as long as a
permittee is implementing the terms and conditions of the HCP, permit,
and other associated documents in good faith. In effect, this
regulation states that the government will honor its commitment as long
as HCP permittees honor theirs.
An activity on private land could also possibly be affected by this
listing if that project (1) would need to be authorized, permitted, or
funded by the Federal government, (2) would be located in habitat
occupied by the scaleshell mussel or in designated critical habitat for
the species, and (3) would have a direct or indirect effect on the
species or its designated critical habitat. Federal programs and
activities of this nature would usually require consultation with the
Service under section 7 of the Act to evaluate the nature and extent of
the adverse impacts and determine if project modification is necessary
to reduce those impacts. Proposed impoundments within currently
occupied streams and rivers are one type of activity that will require
consultation. See the ``Available Conservation Measures'' section for
additional examples of activities that will and will not require
consultation.
While certain activities may require consultation, projects are
rarely terminated due to the presence of a federally listed species,
and private landowners are usually not affected. The consultation
process is the responsibility of the Federal agencies involved. The
majority of section 7 consultations are resolved informally. For
example, consultation is ended at an early stage if the potential
impacts of a proposed project are expected to be discountable,
insignificant, or beneficial to the species. Even if a significant
adverse effect is expected, the consultation can usually be concluded
by developing minor modifications to project plans or designs that
avoid those impacts. If potential impacts are of such nature that a
federally listed species is likely to be adversely affected and such
effects cannot be removed, formal consultation would be required.
However, section 7(b)(4) of the Act allows incidental take of the
listed species resulting from Federal actions if such take is not
likely to jeopardize the continued existence of the species and if
reasonable and prudent measures are implemented to minimize the adverse
impacts of such take. A General Accounting Office audit (1992), which
found that 99.9 percent of all projects reviewed between 1988 and 1992
went
[[Page 51330]]
forward unchanged or with only minor modifications as a result of the
section 7 consultation, attests to the regulatory flexibility afforded
by the Act.
Issue 6: One commenter stated that the same threats (i.e., water
pollution, sedimentation, channelization, and impoundments) listed as
impacting scaleshell mussel in the past (prior to 1950) are stated for
present and future populations. The commenter stated that these
conditions have improved. In Missouri, most of the channelization was
established before the 1930s. Since 1950 land management practices have
also evolved to more effectively control erosion and runoff, and the
impacts of water pollution and sedimentation have been reduced.
Response: The Service recognizes that some of these factors have
improved, particularly land management practices to reduce erosion and
runoff. In fact, the reason scaleshell mussels continue to persist
could possibly be due to these improvements. However, the same threats
that contributed to scaleshell mussels' decline before 1950, are still
being observed and continue to impact scaleshell mussels.
Channelization and new impoundments are currently proposed within the
range of the scaleshell mussel, and water quality degradation and
siltation has recently been documented as a serious threat in areas
still occupied by scaleshell mussels. These threats are ongoing and
qualify the scaleshell mussel for listing (See factor A in the
``Summary of Factors Affecting the Species'' section). The small number
and low density of the remaining populations exacerbate threats and
adverse effects of chance events on the species.
Issue 7: The data cited in the notice of proposed listing provide
inadequate support for listing the scaleshell mussel as an endangered
species. The decline of the scaleshell mussel is not serious enough to
warrant listing. The six potential additional populations (status
unknown), which would increase the current number of populations by
almost 50 percent, merit further investigation before the listing
decision is made.
Response: Under section 4(b)(1)(A) of the Act, a listing
determination must be based solely on the best scientific and
commercial data available regarding the species' biological status and
threats to its existence. Endangered status is assigned to species
which are in danger of extinction throughout all or significant portion
of their range. A species may be determined to be an endangered or
threatened species due to one or more of the five factors described in
section 4(a)(1) of the Act. These factors include (1) the present or
threatened destruction, modification, or curtailment of its habitat or
range; (2) overutilization for commercial, recreational, scientific, or
educational purposes; (3) disease or predation; (4) the inadequacy of
existing regulatory mechanisms; and (5) other natural or manmade
factors affecting its continued existence.
The scaleshell mussel has undergone one of the most extensive range
reductions of all the federally listed freshwater mussel species. It is
considered extirpated from ten states and from 39 of the 55 rivers
within its historical range. Although 14 populations, and possibly six
others, persist, the long-term viability of these populations is
threatened by a variety of ongoing threats (see ``Summary of Factors
Affecting the Species'' discussion). Given the extent of range
reduction that has occurred and the persistence of threats to the
remaining populations, we believe the scaleshell mussel is in danger of
extinction throughout a significant portion of its range.
Issue 8: Detecting population changes by using available data for a
rare species is speculative. Specifically, the proposed rule states
that the long-term viability of scaleshell mussel populations in the
Meramec basin is tenuous. In a recent survey on the Meramec River, more
scaleshell mussels were found than in a past survey. The respondent did
not understand how those data could support a conclusion that the
species is declining.
Response: The Service acknowledges that rare species are difficult
to census, and thus, deriving population trends based on counts of
individuals is difficult and sometimes impossible. It is a common
problem in rare species conservation that, as numbers of a rare species
continue to decline, it becomes increasingly difficult to find and
count the individuals in order to ``prove'' the decline is continuing.
However, reliable inferences on the status and long-term viability of
individual populations, as well as for a species as a whole, can be
made based on ecological principles, small population biology theory,
and observations of threats and habitat loss from field investigations.
For example, population stability implies that recruitment exceeds
mortality. For freshwater mussels, the presence of juveniles serves as
the best evidence for recruitment. Thus, failure to collect juvenile
specimens suggests that the population is declining. Similarly, small
populations are more susceptible to extinction due to chance events,
such as disease, drought, accidental spills of contaminants, or other
fluctuations in local environmental conditions. Thus, even without
multiple years of survey data, we know that low density mussel
populations are vulnerable. Small populations must also rely on
movement of individuals among populations to remain genetically viable.
Thus, mussel populations that are isolated are threatened. In addition
to these biological factors, the presence of threats, regardless of
population size, can substantially influence the conservation status of
a population. Using these factors, the health of individual populations
and the species can be determined.
To ensure consistency and objectivity, Szymanski (1998) developed
criteria based on the aforementioned factors to assign status and trend
categories to each scaleshell mussel population. These criteria were
utilized in the proposed rule. However, a discussion of status and
trends using the same set of limited data was confusing and redundant
to readers. Therefore, in this final rule, we devised a single
classification system (i.e., combined status and trend categories) to
assess population health (Table 1). The revised classification system
differs only in the presentation of the data and the results of its
application are similar to those derived from the Szymanski (1998)
methodology. As a result of additional information that was obtained
during the public comment period, the status or trends reported in the
proposed rule for a few populations differs from those reported herein.
For example, the status of the White River population changed from
extirpated to presumed declining as new information documented a 1999
live scaleshell mussel collection from this river. A discussion of the
criteria used for this classification system is provided in the
``Distribution and Abundance'' section.
With respect to the recent survey work in the Meramec River, the
greater number of scaleshell mussels found in the 1997 survey was
likely due to two aspects of the survey, and not a result of a
population increase (Roberts and Brunderman 2000). First, a special
effort was made to collect this species (i.e., raking the top layer of
the substrate by hand) because it often lies buried in the substrate.
This method likely increased the probability of finding the species
compared to past surveys. Second, lower water levels from drought
conditions exposed a mussel bed at one site, causing scaleshell mussels
to actively crawl on top of the substrate. The collection of only 19
scaleshell mussels, when viewed in light of the modified survey
techniques and the
[[Page 51331]]
high visibility of individual mussels at one mussel bed, is strong
evidence of the extreme rarity of this species.
When attempting to monitor rare species, for which surveys usually
locate only one or several surviving individuals, it is not uncommon
for variations in survey methodology, weather conditions, and even time
of day to affect the results of the survey. For species of extreme
rarity, the effects of these factors can easily obscure the true
population trend for the species. For this reason, we usually use
criteria, in addition to population or density estimates, to evaluate
the health of individual populations and the species as a whole.
Based on the criteria described earlier, the three scaleshell
mussel populations in the Meramec Basin (the Meramec, Bourbeuse, and
Big Rivers) are believed to be declining at the present time. The long-
term persistence of these populations is considered questionable
because of marked habitat loss and other existing threats. Furthermore,
the small number of individuals and low density of these populations
exacerbate the magnitude and adverse impacts of threats (see ``Summary
of Factors Affecting the Species''). Thus, despite the fact that more
scaleshell mussels were collected from the Meramec River in a recent
survey than in the past, other factors indicate that these populations
are threatened and are declining.
Issue 9: One respondent requested clarification of references to
historical and existing distribution and abundance of scaleshell
mussels. The respondent asked if the terms ``populations'' and
``occurrences'' are equivalent and if populations are equal in size and
other qualities.
Response: A ``historical record'' is any site where the scaleshell
mussel has been documented regardless of when it was collected. The
Service believes that recently discovered sites do not represent areas
that have been colonized recently, but rather, they are sites that have
existed historically (i.e., in historical times) and have not been
previously known or sampled by collectors. A description of the
historical range of the scaleshell mussel includes all known records.
In contrast, a description of the existing distribution of the
scaleshell mussel would include only its extant (that is, currently
existing) range.
An ``occurrence'' refers to a site where a scaleshell mussel
specimen has been collected. An occurrence, which may be represented by
one or more specimens, usually indicates the species is present or once
existed in that area, depending on whether the specimen(s) is living or
dead.
In the context of this rule, the term ``population'' refers to all
the current and historical occurrences of scaleshell mussels within a
single river.
It is impossible to determine if past and present scaleshell mussel
populations are equal in size (in terms of number of individuals or
length of stream inhabited), because many surveys conducted near the
turn of the century were not thorough. However, it is believed that
scaleshell mussels historically have always been rare relative to many
other mussel species. Inferences regarding population trend can be made
from existing data (e.g., age-structure, historical vs. current
collections, habitat availability and condition, and threats). For
example, scaleshell mussels were locally abundant in the Kiamichi River
in the past (with 36 specimens collected from one sampling station).
Today, however, no living scaleshell mussel specimens and only 1 fresh
dead specimen were found during exhaustive survey efforts. It is
apparent that scaleshell mussels, although always rare, occur today at
lower densities than in the past in the Kiamichi River (see Issue 8 for
further discussion regarding assessing conservation status). Within
this final rule, populations that were assigned to the same
conservation status do not necessarily have similar population size
(although all populations persist at very low densities) or habitat
quality.
Issue 10: The proposed rule states that scaleshell mussels have not
been found in the Upper Mississippi River basin in over 50 years. One
respondent asked how often sampling has been conducted in the Upper
Mississippi River basin, and what is the likelihood of detecting a
locally rare species.
Response: The historical range of the scaleshell mussel in the
Upper Mississippi River basin includes the states of Illinois, Iowa,
Minnesota, and Wisconsin. Natural resource agencies in these states are
confident enough to consider the scaleshell mussel extirpated since it
has not been collected in over 50 years despite a considerable number
of surveys. Rivers with documented scaleshell mussel occurrences in the
Upper Mississippi River basin include the Mississippi, Minnesota, Iowa,
Cedar, Illinois, Sangamon, and Pecatonica Rivers, and Burdett's Slough
of the Mississippi River (see ``Distribution and Abundance''). All of
these rivers have been surveyed in the last 10-15 years. Surveys
considered here are formal mussel surveys published in technical
reports and scientific journals. Numerous other surveys, which are not
discussed here, also have been conducted in these streams at selected
sites for various Federal projects (e.g., proposed bridges, pipelines,
channelization, etc.). Surveys have been conducted on the Minnesota
River in 1977 and 1999 (Marian Havlik, Malacological Consultants, in
litt. 2000; Tim Yager, Corps, St. Paul District, in litt. 2000). The
Mississippi River mainstem, in particular, has been surveyed
extensively since 1950. The Illinois, Sanagamon, and Pecatonica Rivers
have also been surveyed extensively in the last 15 years (Kevin
Cummings, pers. comm. 2000).
The likelihood of detecting a locally rare species depends on the
amount of time spent searching and the search methods employed. The
most common method used for surveys is timed searches, which produce a
measurement of the number of mussels collected per unit of time spent
searching. Timed searches produce the most complete list of species
(including rare species) at a given site (Strayer et al. 1997, Vaughn
et al. 1997).
Furthermore, the deficiency of suitable mussel habitat, both in
quality and quantity, remaining in this drainage also suggest that
scaleshell mussel persistence is highly unlikely. This is not to say
individuals may not persist in the Upper Mississippi River drainage,
but that the best available scientific information indicates that
population viability is doubtful.
Issue 11: One respondent believes that water turbulence produced by
jet boat motors may be adversely affecting scaleshell mussels and other
freshwater mussels in the Meramec River in Missouri.
Response: The Service recognizes that jet boats, which can produce
powerful water turbulence, could potentially have adverse affects on
freshwater mussels including scaleshell mussels. Jet wash from motors
may contribute to substrate destabilization and/or could dislodge adult
and juvenile mussels from suitable habitat, particularly from shallow
riffles where mussels typically occur. The magnitude and extent to
which this factor may threaten populations, however, is unknown.
Peer Review
In accordance with our July 1, 1994, Interagency Policy on Peer
Review (59 FR 34270) we requested the expert opinions of independent
specialists regarding pertinent scientific or commercial data and
assumptions relating to the supportive biological and ecological
information in the proposed rule. The purpose of such review is to
[[Page 51332]]
ensure that the listing decision is based on scientifically sound data,
assumptions, and analyses, including input of appropriate experts and
specialists.
We requested a formal scientific peer review from four
malacologists who possess expertise on the scaleshell mussel. We
received a written response and comments from two of these experts
within the open comment periods. These experts strongly supported the
listing proposal and agreed with the Service that this species is in
need of Federal protection as an endangered species. One reviewer
stated that the Service was thorough in reviewing this species and that
the status and threats are accurately described. This reviewer felt
that the threats posed by the zebra mussel to the scaleshell mussel, as
discussed in the proposed rule, should not be underestimated.
Additionally, more information was provided in one response regarding
the extant distribution of the scaleshell mussel and threats to its
existence. That information is incorporated into this final rule.
Summary of Factors Affecting the Species
After a thorough review and consideration of all information
available, we determine that the scaleshell mussel should be classified
as an endangered species. We followed the procedures found at section
4(a)(1) of the Act (16 U.S.C. 1531 et seq.) and regulations (50 CFR
part 424) implementing the listing provisions of the Act. We may
determine a species to be endangered or threatened due to one or more
of the five factors described in section 4(a)(1). These factors and
their application to the scaleshell mussel (Leptodea leptodon) are as
follows:
A. The Present or Threatened Destruction, Modification, or Curtailment
of its Habitat or Range.
Arguably, the scaleshell mussel has suffered a greater range
reduction than any other unionid. The range of this species was once
expansive, spanning the Mississippi River Basin in at least 55 rivers
in 13 states (Szymanski 1998). Today, the range is significantly
reduced with known extant populations persisting in only 14,
potentially 20, rivers in three states. The scaleshell mussel has been
eliminated from the entire upper and most of the middle Mississippi
River drainages. Although much of the decline occurred before 1950,
population declines continue in most portions of the species' range,
and numerous threats are impacting the few remaining extant
populations. Water pollution, sedimentation, channelization, sand and
gravel mining, dredging, and impoundments contribute to the decline of
the scaleshell mussel throughout its range and continue to affect
existing populations. A general description of how these factors affect
mussels is given below, followed by specific examples of how these
threats are affecting scaleshell mussels in its extant range. Refer to
Szymanski (1998) for a more detailed discussion of threats to
freshwater mussels.
Mussel biologists generally agree that contaminants are partially
responsible for the decline of mussels (Havlik and Marking 1987,
Williams et al. 1993, Biggins et al. 1996). Mussels are sedentary
filter feeders and are vulnerable to contaminants that are dissolved in
water, associated with suspended particles, or deposited in bottom
sediments (Naimo et al. 1992).
Contaminants enter streams from point and nonpoint sources. Point
source pollution is the entry of material from a discrete, identifiable
source such as industrial effluents, sewage treatment plants, and solid
waste disposal sites. Freshwater mussel mortality from toxic spills and
polluted water is well documented (Ortmann 1909, Baker 1928, Cairns et
al. 1971, Goudreau et al. 1988). Decline and elimination of populations
may be due to acute and chronic toxic effects that result in direct
mortality, reduced reproductive success, or compromised health of the
animal or host fish.
Nonpoint source pollution is the entry of material into the
environment from a diffuse source such as runoff from cultivated
fields, pastures, private wastewater effluents, agricultural feed-lots
and poultry houses, active and abandoned mines, construction, and
highway and road drainage. Stream discharge from these sources may
accelerate eutrophication (i.e., organic enrichment), decrease oxygen
concentration, increase acidity and conductivity, and cause other
changes in water chemistry that are detrimental to the survival of most
mussel species and may impact host fishes (Goudreau et al. 1988, Dance
1981, Fuller 1974).
Sediment is material that is suspended in the water, and is being
transported, or has been moved, as the result of erosion (USSCS 1988).
Although sedimentation is a natural process, agricultural encroachment,
channelization, impoundments, timber harvesting within riparian zones,
heavy recreational use, urbanization, and other land use activities can
accelerate erosion (Waters 1995, Myers et al. 1985, Chesters and
Schierow 1985). The water quality impacts caused by sedimentation are
numerous. Generally, it affects aquatic biota by altering the
substratum and by altering the chemical and physical composition of the
water (Ellis 1936, Myers et al. 1985, USSCS 1988). Sedimentation
directly affects freshwater mussel survival by interfering with
respiration and feeding. Due to their difficulty in escaping smothering
conditions (Imlay 1972, Aldridge et al. 1987), a sudden or slow
blanketing of stream bottom with sediment can suffocate freshwater
mussels (Ellis 1936). Sediment particles may carry contaminants toxic
to mussels (Naimo et al. 1992). Increased sediment levels may also
reduce feeding efficiency (Ellis 1936), which can lead to decreased
growth and survival (Bayne et al. 1981).
Channelization, sand and gravel mining, and dredging operations
physically remove mussels from the water and may also bury or crush
mussels (Watters 1995). Other effects of these activities extend
upstream and downstream of the excavated area. Headcutting, the
upstream progression of stream bed destabilization and accelerated bank
erosion, can affect an area much larger than the dredging site
(Hartfield 1993). In severe cases, this erosional process can extend
for several miles upstream. As relatively immobile bottom-dwelling
invertebrates, mussels are particularly vulnerable to channel
degradation (Hartfield 1993). Accelerated erosion also releases
sediment and pollutants, and in some instances, diminishes mussel
diversity and habitat as documented in the Yellow and Kankakee Rivers
in Indiana, the Big Vermillion River in Illinois, and the Ohio River
(Fuller 1974).
Gravel mining has recently become a more serious threat for
scaleshell mussels range-wide. In 1997, a court ruling changed the
interpretation of the CWA as it applies to the regulation of gravel
mining (Roell 1999). Previously, gravel mining was more strictly
regulated because ``incidental fallback'' (the incidental soil movement
from excavation, such as the soil that is disturbed when dirt is
shoveled, or back-spill that comes off a bucket and falls into the same
place from which it was removed) was considered fill in surface waters,
thus triggering section 404 of the CWA and the permitting process of
the Corps. Prior to the 1997 ruling, gravel mining operators were
required to obtain a Corps section 404 permit and follow several
conditions outlined on the permit. Except in very small tributaries,
the Corps required all operators to establish a streamside and riparian
buffer and prohibited removing gravel from flowing water (i.e., no in-
stream mining) or from below the water
[[Page 51333]]
table (Danny McKlendon, Corps, St. Louis District, pers. comm. 1998).
These requirements avoided most adverse effects to mussels including
headcutting, channel modification, and the physical crushing or removal
of mussels. Furthermore, the Corps' permit process included
consultation with the Service concerning the presence of federally
listed species at each proposed mining site. However, the 1997 ruling
eliminated the Corps authority to regulate most instream gravel mining
activities, thereby eliminating the section 404 permit and the
conditions that protected mussel beds. Therefore, the scaleshell mussel
has lost much of its protection from gravel mining. Only activities
resulting in discharge of fill material greater than incidental
fallback (such as instream gravel stockpiling, stream crossings, and
select removal methods) are regulated. However, many gravel mining
operations may not fall under this category.
Impoundments negatively affect mussels both upstream and downstream
by inducing scouring, changing water temperature regimes, and altering
habitat, food, and fish host availability (Caryn Vaughn, in litt.
1997). Impoundments permanently flood stream channels and eliminate
flowing water that is essential habitat for most unionids, including
scaleshell mussels (Fuller 1974, Oesch 1995). Scouring is a major cause
of mussel mortality below dams (Layzer et al. 1993). Most detrimental,
however, is the disruption of reproductive processes. Impoundments
interfere with movement of host fishes, alter fish host assemblages,
and isolate mussel beds from each other and from host fishes (Stansbery
1973, Fuller 1974, Vaughn 1993, Williams et al. 1993). The result is
diminished recruitment (Layzer et al. 1993). Dams are effective
barriers to fish host movement and migration that unionids depend on
for dispersal. Mussels living upstream from the dam can become
reproductively isolated from those living downstream causing a decrease
in genetic diversity. Even small, lowhead dams can hinder fish movement
and isolate mussel beds from fish hosts and from each other. For
example, Watters (1996) determined that the upstream distribution of
two mussel species, the fragile papershell (Leptodea fragilis) and pink
heelsplitter (Potamilus alatus) stopped at lowhead dams. These species,
like the scaleshell mussel, are believed to use the freshwater drum as
a sole host.
The same threats that caused the extirpation of historical
populations of scaleshell mussel still exist and continue to threaten
extant populations. This species appears to be especially susceptible
to contamination and sedimentation. Historically, the species was
widespread and occurred in diverse habitats. Today, scaleshell mussels
no longer occur at disturbed sites that still support other endangered
unionids (Szymanski 1998). This suggests that scaleshell mussels are
especially sensitive to degraded water quality. Given the pervasiveness
of the sources of pollution and sedimentation, it is apparent that
these threats continue to be problematic for the remaining scaleshell
mussel populations.
Upper Mississippi River Basin
The scaleshell mussel formerly occurred in eight rivers and
tributaries within the Upper Mississippi Basin. However, this species
has not been found in more than 50 years and is believed extirpated
from this region (Kevin Cummings, in litt. 1994). We believe the same
factors that have caused declines and extirpations of other mussel
species including impoundments, pollution, sedimentation, and
channelization and dredging activities, have caused the disappearance
of scaleshell mussels from the Upper Mississippi River Basin.
Middle Mississippi River Basin
Similar to the Upper Mississippi River Basin, impoundments,
pollution, sedimentation, and channelization and dredging activities
are believed to have led to the extirpation of the scaleshell mussel
from the entire Ohio River Basin. These same threats continue to
adversely affect extant populations in the middle Mississippi River
Basin. Scaleshell mussel habitat in the Meramec River Basin has been
reduced in recent years. In 1979, Buchanan found living or dead
scaleshell mussels in the lower 180 km (112 mi) of the Meramec River
(Buchanan 1980). In 1997, living or dead scaleshell mussels were
collected only in the lower 96 km (60 mi) of the river (Roberts and
Bruenderman 2000). While portions of the lower reach continue to
provide suitable habitat, mussel species diversity and abundance above
mile 60 have declined noticeably in the last 20 years and 9 mussel beds
are no longer present between river mile 21.5 and 145.7. Roberts and
Bruenderman (2000) attributed this decline primarily to the loss of
channel stability. Within the Meramec Basin, the Bourbeuse River has
undergone the greatest change with respect to mussel populations. In
particular, mussel populations have declined in the lower river.
Whereas Buchanan (1980) found this section of the Bourbeuse River to
have the greatest mussel diversity, this stretch was nearly devoid of
mussels when resurveyed in 1997. Additionally, five mussel beds are no
longer present between miles 0.4 and 137. Buchanan (in litt. 1997) and
Roberts and Bruenderman (2000) attributed this decline to habitat loss
from sedimentation, eutrophication, and substrate destabilization.
The Big River has the lowest species diversity and abundance in the
Meramec River Basin. Buchanan (1980) attributed this to the effects of
lead and barite mining. While most mining operations have ceased, 45
dams retaining mine waste and numerous waste piles remain in the Big
River Basin. Most of those dams were improperly constructed or
maintained. The Corps found that only one of the 45 dams was safe and
27 received the worst possible rating and could fail during a flood.
The poor condition of the dams has led to large influxes of mine waste
into the Big River from dam collapse (MDC 1997). For example, since
1978, a ruptured tailings dam has discharged 63,000 cubic meters
(81,000 cubic yards) of mine tailings into the Big River covering 40 km
(25 mi) of stream bottom and negatively impacting the lower 129 km (80
mi) of the river (Alan Buchanan, in litt. 1995), making it less
suitable for mussels.
While no major impoundments exist in the Meramec River Basin,
several old mill dams (low-head dams) affect the mainstem of the Big
and Bourbeuse Rivers. Five dams are still in place along the lower 48
km (30 mi) of the Big River, and one dam exists in the lower Bourbeuse
River. These structures are barriers to host fish movement during
normal flows (MDC 1997) and thus, continue to depress reproductive
rates of scaleshell and other mussels.
Gravel mining poses an imminent threat to scaleshell mussel
populations in the Meramec River Basin due to the high, and increasing,
level of interest in gravel mining in the basin (Roberts and Brunderman
2000). For example, between 1994 and 1998, the Corps issued permits for
230 sites. Additional sites were mined without a permit, but the number
of these unauthorized operations is unknown. (Danny McKlendon, Corps,
St. Louis District, in litt. 1998).
In 1994, several areas of the Gasconade River channel were highly
unstable, possibly a result of riparian vegetation removal in
conjunction with the 1993 flood. These areas had high cut mud banks
with trees fallen into the river, unstable substrate, and contained
very few mussels. Buchanan (1994) predicted that habitat degradation on
this river would continue and
[[Page 51334]]
postulated that the mussel fauna would be further impacted with some
species possibly disappearing. He noted that below river mile 6, only
one stable gravel bar contained a diverse mussel fauna. High silt
deposition from the Missouri River prohibits the formation of mussel
habitat below this area.
The majority of the Osage River system has been impounded and is no
longer suitable for freshwater mussels. The majority of remaining
mussel habitat occurs below Bagnell dam in the lower 80 miles of the
Osage River proper. This river reach is affected by the operation of
Bagnell dam, which alters flow and temperature regimes, lowers
dissolved oxygen levels, and causes channel scouring and accelerated
bank erosion. Several instream gravel mining operations currently exist
in the Osage River that physically remove mussels from the water and
cause headcutting and siltation.
Lower Mississippi River Basin
Channelization, levee construction, diversion ditches, control
structures, and floodways have drastically altered much of the St.
Francis River from the mouth above Helena, Arkansas, to Wappapello Dam,
Missouri (Ahlstedt and Jenkinson 1987, Bates and Dennis 1983). Bates
and Dennis (1983) determined that of the 54 sites sampled, 15 were
productive, 10 were marginal, and 29 had either no shells or dead
specimens only. They identified 77 km (48 mi) that may still provide
suitable mussel habitat, but did not collect scaleshell mussels. All
the remaining river miles are unsuitable for mussels.
The White River between Beaver Reservoir and its headwaters, due to
municipal pollution, gravel dredging, and dam construction, is no
longer suitable for mussels (Gordon 1980). Navigational maintenance
activities continue to destroy habitat from Newport to the confluence
of the Mississippi River (Bates and Dennis 1983). This habitat
destruction has relegated mussel species to a few refugial sites.
Species richness in the Spring River below river mile nine has
declined markedly from past surveys, with the lower 5.0 km (3.0 mi) of
river completely depleted of mussels and no longer supporting suitable
habitat (Miller and Hartfield 1986, Gordon et al. 1984). Sand and
gravel dredging; the destruction of stream banks, disturbance of mussel
beds, and the deposition of wastes from livestock movements; siltation;
and surface run-off of pesticide and fertilizer appear to be
contributing factors in the degradation of this river reach (Gordon et
al. 1984).
Within Frog Bayou, potential habitat is restricted to the area
between Rudy and the confluence of the Arkansas River. Within this
area, streambank modifications and in-stream gravel mining are
degrading scaleshell mussel habitat. Two reservoirs, one near Maddux
Spring and the other at Mountainburg, impact the river above Rudy.
Below the confluence of the Arkansas River, Gordon (1980) did not find
live mussels, likely due to dredging activities (Gordon 1980).
The proposed Tuskahoma Reservoir (located above Hugo Reservoir) is
a potential threat to mussels in the Kiamichi River. Although the Corps
has authorized construction, the lack of a local sponsor has rendered
the project ``inactive'' (David Martinez, Service, Tulsa, pers. comm.
1997). If constructed, the adverse effects associated with reservoirs
(including permanent flooding of the channel and disruption of
reproduction) are likely to destroy the mussel fauna both above and
below the proposed dam site.
Sewage pollution, gravel dredging, and reservoirs continue to
impact the Little River. Pine Creek Reservoir impounds the mainstem of
the river. Further downstream, Broken Bow Reservoir impounds a major
tributary to the Little River, the Mountain Fork River. Below Pine
Creek Lake, the mussel fauna is severely depleted but recovers with
increasing distance from the impoundment (Caryn Vaughn, in litt. 1997).
However, the discharge of reservoir water from Pine Creek and periodic
discharge of pollution from Rolling Fork Creek seriously impact any
remaining scaleshell mussels and prohibit any future recolonization
(Clarke 1987).
Hydroelectric dams and artificial lakes have impacted the Ouachita
River. The ``Old River'' (an oxbow system off the mainstem), is now
essentially a series of muddy, stagnant pools, with water quality
problems resulting from surrounding dumps (Clarke 1987).
In summary, many of the same threats that caused the extirpation of
historical populations of scaleshell mussels still exist and continue
to threaten extant populations. Nonpoint and point source pollution is
currently affecting the Spring River in Arkansas (Gordon et al. 1984,
Miller and Hartfield 1986) and the Little River in Oklahoma (Clarke
1987, Vaughn 1994). Loss of stable substrates and sedimentation is
causing deleterious effects in the Meramec and Bourbeuse Rivers,
Missouri (Sue Bruenderman, pers. comm. 1998); Gasconade River, Missouri
(Buchanan 1994); Frog Bayou, Arkansas (Gordon 1980); and Spring River,
Arkansas (Gordon et al. 1984). Unregulated sand and gravel mining are
eliminating important pool habitat (for both scaleshell mussels and
potential fish hosts) in the Meramec, Bourbeuse, Big, and Gasconade
Rivers in Missouri (Bruenderman, MDC, pers. comm. 1998). Impoundments,
channelization, and other dredging activities (e.g., sand and gravel
mining) are destroying mussel beds and impairing water quality in Frog
Bayou, Arkansas (Gordon 1980); St. Francis River, Arkansas (Ahlstedt
and Jenkinson 1987); White River, Arkansas (Bates and Dennis 1983);
Spring River, Arkansas (Gordon et al. 1984); and Ouachita River,
Arkansas (Clarke 1987). The proposed Kiamichi River Reservoir, if
constructed, will have adverse impacts on any remaining populations in
Oklahoma. Nearly all scaleshell mussel populations are now restricted
to small stretches of rivers with little, if any, potential for
expansion or recolonization to other areas. For example, sewage
pollution, gravel dredging, and reservoir construction have degraded
the Little River in Oklahoma to the extent that only a few small
stretches are able to support mussels.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
It is unlikely that commercial mussel collectors ever purposefully
collected scaleshell mussels because of their small size and thin
shell. It is probable, however, that over-harvesting activities that
removed entire mussel beds impacted scaleshell mussel populations. For
example, according to local fishermen, during a period of extended
drought, mussel harvesters severely over-collected mussel beds in the
Spring and Black Rivers and completely destroyed most beds (Gordon et
al. 1984). Thus, scaleshell mussel populations may have been impacted
by habitat destruction (i.e., disturbance of stream bottom), trampling,
and removal of individuals from the stream. Individuals dislodged from
the stream bottom could be washed away into unsuitable habitat. Even
for mussels returned to the stream, mortality can still occur (Williams
et al. 1993). Today, intensive mussel collecting activity will have
severe adverse affects on existing populations, because scaleshell
mussels now occur in very small, isolated areas. The destruction of
only a few individuals could be a contributing factor in the
extirpation of some populations.
As scaleshell mussels become more uncommon, the interest of
scientific and
[[Page 51335]]
shell collectors will increase. Scaleshell mussel occurrences are
generally localized, easily accessible, and exposed during low flow
periods, and, therefore, are also vulnerable to take for fish bait,
curiosity, or vandalism. Up to five freshwater mussels per day,
including scaleshell, may be legally collected in Missouri and used for
fishing bait (Sue Bruenderman, pers. comm. 1998). However, the low
density of scaleshell mussels minimizes the likelihood of a scaleshell
being collected.
C. Disease or Predation
Although natural predation is usually not a factor for stable,
healthy mussel populations, small mammal predation could pose a problem
for scaleshell mussel populations (Gordon 1991). While the large size
or thick shells of some species afford protection from small mammal
predators, the small size and fragile shell of the scaleshell mussel
makes it an easy and desirable prey species. Small mammals, such as
muskrats and racoons, may be common predators of scaleshell mussels
throughout their range, particularly during periods of low water. For
example, fresh scaleshell mussel shells were found among other species
at several active raccoon middens (feeding areas) during a freshwater
mussel survey of the Meramec and Bourbeuse Rivers (Roberts and
Bruenderman 2000). These mammals are so effective at finding and eating
freshwater mussels that malacologists consider collecting dead shells
from middens a good way to determine the presence of rare species.
Extant scaleshell mussel populations in Arkansas and Oklahoma are
small, isolated, and have very limited recolonization potential. Thus,
the removal of even a small number of individuals could significantly
affect these populations. Small populations are less resilient to these
natural predators, and therefore, are much more threatened by them.
Consequently, predation could exacerbate ongoing population declines of
scaleshell mussels.
Bacteria and protozoans persist at unnaturally high concentrations
in streams with high sediment load or in water bodies affected by point
source pollution, such as sewage treatment plants (Goudreau et al.
1988). At such concentrations, mussel ova and glochidia are more
subject to infection (Ellis 1929). Disease and parasites may have
caused major die-offs of freshwater mussels in the late 1970s
throughout the eastern United States (Neves 1986). For example,
significant die-offs of freshwater mussels occurred in 1977 and 1978 in
the Meramec and Bourbeuse Rivers. Large numbers of mussels of all
species, including scaleshell, were lost. Buchanan (1986) presumed an
epizootic or other disease caused the die-off since no environmental
impact was reported or could be found.
D. The Inadequacy of Existing Regulatory Mechanisms
The passage of the CWA resulted in many positive consequences for
freshwater ecosystems (including a decrease in lead and fecal coliform
bacteria), and set the stage for the regulations and the water
standards that exist today. Goals of the CWA include the protection and
enhancement of fish, shellfish, and wildlife; providing conditions
suitable for recreation in surface waters; and eliminating the
discharge of pollutants into U.S. waters. However, despite the
implementation of the CWA, degraded water quality still presents
problems for sensitive aquatic organisms such as freshwater mussels.
Specifically, nationwide stream and lake sampling has indicated
continuing increases in nitrate, chloride, arsenic, and cadmium
concentrations (Neves 1993). Nonpoint pollution sources appear to be
the cause of increases in nitrogen. Many of the impacts discussed above
occurred in the past as unintended consequences of human development.
Improved understanding of these consequences has led to regulatory
(e.g., CWA) and voluntary measures (e.g., best management practices for
agriculture and silviculture) and improved land use practices that are
generally compatible with the continued existence of the scaleshell
mussel. Nonetheless, the scaleshell mussel is highly restricted in
numbers and distribution and shows little evidence of recovering from
historical habitat degradation and losses.
As discussed previously (see Factor A under ``Summary of Factors
Affecting the Species'' and Issue 4), a 1997 court ruling reduced the
Corps' authority to regulate instream gravel mining. The MDNR is
currently responsible for regulating gravel mining in Missouri, but has
limited regulatory authority, and several conditions that were
previously required by the Corps are no longer in place. These
guidelines avoided many adverse effects to mussels including
headcutting, channel modification, and the physical removal of mussels.
Further, city, county, and State operators using their own equipment
and private operations are not required to obtain a MDNR permit for
instream gravel mining. In Arkansas, instream gravel mining will still
be controlled by the Arkansas Open-Cut Mining and Land Reclamation
Code, which contains required conditions to reduce impacts (Roell
1999).
Additionally, since MDNR is not a Federal agency, section 7 of the
Act, which required the Corps to consult with the Service regarding the
presence of federally listed species at proposed gravel mining sites,
is no longer applicable. Without the section 7 consultation process,
mussel beds containing federally listed species could be adversely
affected by gravel mining operations.
The Corps will still retain oversight authority and require a
permit for gravel mining activities that deposit fill into streams
under section 404 of the CWA. Additionally, a Corps permit would be
required under section 10 of the Rivers and Harbors Act for navigable
waterways including the lower 80 km (50 mi) of the Meramec River.
However, many gravel mining operations do not fall under these two
categories.
Although recognized by species experts as threatened in Arkansas,
the scaleshell mussel is not afforded state protection. Missouri and
Oklahoma list the scaleshell mussel as a species of conservation
concern (Sue Bruenderman, in litt. 1998; Caryn Vaughn, pers. comm.
1995). However, these designations are primarily used for planning and
communication purposes and do not afford any significant State
protection from direct take and habitat destruction (David Martinez,
pers. comm. 1997; Paul McKenzie, Service, Columbia, MO, pers. comm.
1997). Therefore, scaleshell mussels may be collected, harmed, or
killed in Missouri and Oklahoma without a permit. Without additional
regulations providing habitat protection, as well as protection from
direct and indirect take, populations of scaleshell mussels will
continue to decline and disappear.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
As a consequence of the above factors, the inherent biological
traits of freshwater mussels increase their vulnerability to extinction
(Neves 1993). For example, the larval stage (glochidium) of most
mussels is dependent on a few or one specific host fish (Neves 1993).
The scaleshell mussel is believed to use the freshwater drum as its
sole host fish species. This trait greatly reduces the likelihood of
contact between glochidia and suitable hosts. Watters (1995) postulated
that the glochidia must acquire suitable hosts within 24 hours to
survive. Therefore, a reduction or loss of host fish
[[Page 51336]]
populations will lead to reduced glochidial survival and a decline in
reproductive success, which will inevitably adversely impact scaleshell
mussel populations.
Once a larva successfully transforms on a host, it is further
challenged with dropping off onto suitable habitat. Watters (1995)
reported that estimated chances of successful glochidial transformation
and excystment (detachment) range between 0.0001 percent (Jansen and
Hanson 1991) and 0.000001 percent (Young and Williams 1984). As a
result of fish host-specificity and the difficulty of locating suitable
habitat, even under optimal conditions, freshwater mussel population
growth occurs very slowly. Furthermore, the sedentary nature of mussels
limits their dispersal capability. This trait, coupled with low
recruitment success, translates into the need for decades of
immigration and recruitment for re-establishment of self-sustaining
populations.
The small number and low density of the remaining scaleshell mussel
populations exacerbate the threats to its survival posed by the above
factors. Although the scaleshell mussel was always locally rare though
broadly distributed, the widespread loss of populations and the limited
number of collections in recent years indicates that the current
population densities are much lower (due to the previously identified
threats) than historical levels. Despite any evolutionary adaptations
for rarity, habitat loss and degradation increase a species'
vulnerability to extinction (Noss and Cooperrider 1994). Numerous
studies have shown that with decreasing habitat availability, the
probability of extinction increases. Similarly, as the number of
occupied sites decreases, and the distances between them increases, the
likelihood of extinction increases (Vaughn 1993). This increased
vulnerability is the result of chance events. Environmental variation,
random or predictable, naturally causes fluctuations in populations.
However, small and low density populations are more likely to fluctuate
below the minimum viable population (i.e., the minimum number of
individuals needed in a population to persist). If population levels
stay below this minimum size, an inevitable, and often irreversible,
slide toward extinction will occur. Further, the shorter life span of
the scaleshell mussel may render it less able to tolerate periods of
poor recruitment or increased mortality than are longer-lived mussel
species (Chris Barnhart, in litt. 1999).
Small populations are also more susceptible to inbreeding
depression and genetic drift. Populations subjected to either of these
problems usually have low genetic diversity, which reduces fertility,
survivorship, and the ability to adapt to environmental changes. Also,
chance variation in age and sex ratios can affect birth and deaths
rates. Skewing of these ratios may lead to death rates exceeding the
birth rates, and when this occurs in small populations there is a
higher risk of extinction.
Similarly, the fertilization success of mussels may be related to
population density, with a threshold density required for any
reproductive success to occur (Downing et al. 1993). Small mussel
populations may have individuals too scattered to reproduce
effectively. Many of the remaining scaleshell mussel populations may be
at or below this threshold density. These populations will be, if the
aforementioned threats go unabated, forced below or forced to remain
below the minimum threshold. As a result, reproduction is diminished or
ceases, and the current decline to extinction will be accelerated.
Furthermore, species that occur in low numbers must rely on
dispersal and immigration for long-term persistence. In order to retain
genetic viability and guard against chance extinction, movement between
populations must occur. Although the scaleshell mussel naturally occurs
in patches within a river and necessarily possesses mechanisms to adapt
to such a discontinuous distribution, anthropogenic (man-made)
influences have fragmented and further lengthened the distance between
patches. Empirical studies have shown that with increasing isolation,
immigration and colonization rates decrease. Also, as previously
explained, natural recolonization of mussels occurs at a very low rate
(Vaughn 1993). Therefore, preservation of a population (including all
partially isolated patches in a river) structure is imperative for
long-term freshwater mussel survival. Unfortunately, many of the extant
scaleshell mussel populations now occur as single, isolated sites.
These highly isolated populations are very susceptible to chance events
and local extirpation with no chance of recolonization.
Lastly, the recent invasion of the exotic zebra mussel (Dreissena
polymorpha) poses a substantial threat to native unionids (Herbert et
al. 1989). The introduction of Dreissena into North America probably
resulted from an ocean-crossing vessel that discharged freshwater
ballast from Europe containing free-swimming larvae of the zebra mussel
(Griffiths et al. 1991). Since its introduction in 1985, this prolific
species has spread throughout the Mississippi River and many of its
tributaries including the Illinois and Ohio basins and the Arkansas and
Tennessee rivers. Zebra mussels starve and suffocate native mussels by
attaching to their shells in large numbers. The spread of this prolific
species has caused severe declines of native freshwater mussel species
in many areas (Tucker et al. 1993; Kent Kroonemeyer, Service in litt.
1994; Illinois Natural History Survey, in litt. 1995; Corps, in litt.
2000).
Given that recreational and commercial vessels greatly facilitate
the spread of zebra mussels, and because of the proliferation and
spread that has already occurred, invasion of the zebra mussel into
portions of the middle and lower Mississippi Basin is likely (Alan
Buchanan, pers. comm. 1995). If zebra mussels successfully colonize
rivers occupied by scaleshell mussels, its continued survival will be
further jeopardized. The zebra mussel has been found recently within
the scaleshell mussels' extant range in the middle Mississippi Basin.
In the summer of 1999, a live zebra mussel was collected in the Lower
Meramec River at river mile 6.9 (Chris Barnhart, in litt. 1999). The
Meramec Basin appears to support the largest remaining populations of
scaleshell mussels. Zebra mussels are likely to successfully colonize
the Meramec River, because it appears to be similar in most ways to
other tributaries of the Mississippi River that already have
established populations of zebra mussels. Another live zebra mussel was
collected in 1999 from the Missouri River near Sioux City, Iowa (John
LaRandeau, in litt. 1999). If zebra mussels have successfully colonized
the Missouri River, it is likely that they will spread into the
Gasconade River, which has perhaps the largest population of scaleshell
mussels next to those in the Meramec Basin.
Conclusion
Significant habitat loss, range restriction, and population
fragmentation and size reduction have rendered the scaleshell mussel
vulnerable to extinction. The scaleshell mussel has disappeared from
the entire upper and most of the middle Mississippi River drainages. Of
the 55 known historical populations, 14 and possibly 20, remain.
Although much of the decline occurred before 1950, population declines
continue in most of the species' range, and numerous threats, including
water quality degradation, loss of stable substrates, sedimentation,
channelization, gravel mining, dredging, and impoundments,
[[Page 51337]]
are impacting the few remaining viable extant populations. The small
number and low density of the remaining scaleshell mussel populations
exacerbate the threats and adverse effects of chance events to
scaleshell mussels. Only one of the remaining populations is believed
to be stable.
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the scaleshell mussel in determining this rule final. The
present distribution and abundance of the scaleshell mussel are at risk
given the potential for these impacts to continue. Therefore, based on
this evaluation, it is appropriate that the scaleshell mussel be listed
as an endangered species. The Act defines an endangered species as one
that is in danger of extinction throughout all or a significant portion
of its range. A threatened species is one that is likely to become an
endangered species in the foreseeable future throughout all or a
significant portion of its range. Endangered status is appropriate for
the scaleshell mussel given the extent and magnitude of habitat loss,
range restriction, and population fragmentation that has occurred, and
the continued vulnerability of this species to such threats. These
threats are ongoing, and there is clear evidence that some of them,
such as sand and gravel mining in the core of the species' current
range, have actually increased their adverse impacts on mussel habitat
in the last several years.
Critical Habitat
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 means 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.
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, the Secretary designate critical habitat at the time
the species is determined to be endangered or threatened. Section
4(b)(2) of the Act requires us to consider economic and other relevant
impacts of designating a particular area as critical habitat on the
basis of the best scientific data available. The Secretary may exclude
any area from critical habitat if she/he determines that the benefits
of such exclusion outweigh the benefits of its inclusion, unless to do
so would result in the extinction of the species. Our regulations (50
CFR 424.12(a)) state that designation of critical habitat is not
prudent when one or both of the following situations exist--(i) the
species is threatened by taking or other activity and the
identification of critical habitat can be expected to increase the
degree of threat to the species or (ii) such designation of critical
habitat would not be beneficial to the species.
In the proposed rule, we indicated that designation of critical
habitat was not prudent because of a concern that publication of
precise maps and descriptions of critical habitat in the Federal
Register could increase the vulnerability of this species to incidents
of collection and vandalism. We also indicated that designation of
critical habitat was not prudent because we believed it would not
provide any additional benefit beyond that provided by the listing as
endangered.
In the last few years, a series of court decisions have overturned
Service determinations regarding a variety of species that designation
of critical habitat would not be prudent (e.g., Natural Resources
Defense Council v. U.S. Department of the Interior 113 F. 3d 1121 (9th
Cir. 1997); Conservation Council for Hawaii v. Babbitt, 2 F. Supp. 2d
1280 (D. Hawaii 1998)). Based on the standards applied in those
judicial opinions, we have reexamined the question of whether critical
habitat for the scaleshell mussel would be prudent.
Due to small population size, the scaleshell mussel is vulnerable
to unrestricted collection, vandalism, or other disturbance. We remain
concerned that these threats might be exacerbated by the publication of
critical habitat maps and further dissemination of locational
information. However, we have examined the evidence available for the
scaleshell mussel and have not found specific evidence of taking,
vandalism, collection, or trade of these species or any similarly
situated species. Consequently, consistent with applicable regulations
(50 CFR 424.12(a)(1)(i)) and recent case law, at this time we do not
expect that the identification of critical habitat will increase the
degree of threat to this species of taking or other human activity.
In the absence of a finding that critical habitat would increase
threats to a species, if any benefits would result from a critical
habitat designation, then a prudent finding is warranted. In the case
of scaleshell mussel, designation of critical habitat may provide some
benefits.
In general, critical habitat identifies areas that may require
special management considerations or protection, and its designation
may provide protection to areas where significant threats to a species
have been identified. Critical habitat receives protection from
destruction or adverse modification through required consultation under
section 7 of the Act with regard to actions carried out, funded, or
authorized by a Federal agency. Section 7 also requires conferences on
Federal actions that are likely to result in the adverse modification
or destruction of proposed critical habitat. Aside from the protection
that may be provided under section 7, the Act does not provide any
other forms of protection to lands designated as critical habitat.
Section 7(a)(2) of the Act requires Federal agencies to consult
with the Service to ensure that any action they carry out, authorize,
or fund does not jeopardize the continued existence of a federally
listed species or destroy or adversely modify designated critical
habitat. A critical habitat designation for habitat currently occupied
by a species would usually result in the same outcome under section 7
consultation as would occur if the critical habitat had not been
designated, because an action that destroys or adversely modifies such
critical habitat would also be likely to result in jeopardy for the
species. However, there may be instances where section 7 consultation,
and subsequent protection, would be triggered only if critical habitat
is designated, such as areas where a species is not believed to
currently exist, but where reestablishment is needed to conserve the
species. In the case of the scaleshell mussel, the species' low numbers
and highly fragmented distribution will likely require the
establishment of additional populations beyond the 14 known extant
populations. Critical habitat designation of areas most suitable for
future establishment of scaleshell mussel populations would provide
habitat protection by triggering section 7 consultations for Federal
agency actions.
Designation of critical habitat can help focus conservation
activities for a listed species by identifying areas that contain the
physical and biological features essential for the conservation of
[[Page 51338]]
that species, regardless of whether the areas are currently used by the
species. Designation of critical habitat alerts the public as well as
land-managing agencies to the importance of these areas.
We find that critical habitat designation is prudent for the
scaleshell mussel due to the probable benefits to the species described
above. We find that these benefits are not outweighed by potential
increased threats from designating critical habitat.
However, our budget for listing activities is currently
insufficient to allow us to immediately complete all of the listing
actions required by the Act. Listing the scaleshell mussel without
designation of critical habitat will allow us to concentrate our
limited resources on other listing actions that must be addressed,
while allowing us to invoke protections needed for the conservation of
this species without further delay. This is consistent with section
4(b)(6)(C)(i) of the Act, which states that final listing decisions may
be issued without critical habitat designations when it is essential
that such determinations be promptly published. The legislative history
of the 1982 Act amendments also emphasized this point: ``The Committee
feels strongly, however, that, where biology relating to the status of
the species is clear, it should not be denied the protection of the Act
because of the inability of the Secretary to complete the work
necessary to designate critical habitat. * * * The committee expects
the agencies to make the strongest attempt possible to determine
critical habitat within the time period designated for listing, but
stresses that the listing of species is not to be delayed in any
instance past the time period allocated for such listing if the
biological data is clear but the habitat designation process is not
complete'' (H.R. Rep. No. 97-567 at 20 (1982)). We will prepare a
critical habitat designation in the future as soon as there are
resources available and other listing duties under the Act will allow.
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
conservation actions by Federal, State, and local agencies, private
organizations, and individuals. The Act provides for possible land
acquisition and 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 taking and harm are
discussed, in part, below.
Section 7(a) of the Act, as amended, requires Federal agencies to
evaluate their actions with respect to any species that is listed as
endangered or threatened and with respect to its critical habitat, if
any is being designated. Regulations implementing this interagency
cooperation provision of the Act are codified at 50 CFR Part 402.
Section 7(a)(2) of the Act requires Federal agencies to ensure that
activities they authorize, fund, or carry out are not likely to
jeopardize the continued existence of such a species or to destroy or
adversely modify its critical habitat. If a Federal action may affect a
listed species or its critical habitat, the responsible Federal agency
must enter into consultation with us.
Federal activities that could occur and impact the scaleshell
mussel, include, but are not limited to, issuance of permits for
reservoir construction, stream alterations, waste-water facility
development, water withdrawal projects, pesticide registration,
agricultural assistance programs, mining, road and bridge construction,
Federal loan programs, water allocation, and hydropower licensing or
relicensing. In our experience, nearly all section 7 consultations
result in protecting the species while still meeting the project's
objectives.
The Act and implementing regulations found at 50 CFR 17.21 set
forth a series of general prohibitions and exceptions that apply to all
endangered wildlife. The 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,
capture, 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 endangered
species. It also is illegal to possess, sell, deliver, carry,
transport, or ship any such wildlife that has been taken illegally.
Certain exceptions apply to our agents and agents of State conservation
agencies.
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 (e.g., activities subject to
sections 402, 404, and 405 of the CWA and discharges regulated under
the National Pollutant Discharge Elimination System).
(2) Actions that may affect the scaleshell mussel 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 pursuant to 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 if a scaleshell mussel is collected it is
immediately released, unharmed.
Activities that we believe could potentially result in take of
scaleshell mussels include but are not limited to:
(1) Illegal collection or capture of the species;
(2) Unlawful destruction or alteration of the species' occupied
habitat (e.g., 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 scaleshell mussels.
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 Columbia, Missouri Field office (see ADDRESSES). 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, Whipple Federal
Building, 1 Federal Drive, Fort Snelling, MN 55111 (Phone 612/713-5350;
Fax 612/713-5292).
[[Page 51339]]
National Environmental Policy Act
We have determined that we do not need to prepare an Environmental
Assessment, as defined under the authority of the National
Environmental Policy Act of 1969, in connection with regulations
adopted pursuant to section 4(a) of the Endangered Species Act, as
amended. We published a notice outlining our reasons for this
determination in the Federal Register on October 25, 1983 (48 FR
49244).
Paperwork Reduction Act
This rule does not contain any new collections of information other
than those already approved under the Paperwork Reduction Act, 44
U.S.C. 3501 et seq., and assigned Office of Management and Budget
control number 1018-0094. 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 control number. For additional
information concerning permit and associated requirements for
endangered species, see 50 CFR 17.22.
References Cited
A complete list of all references cited herein, as well as others,
is available upon request from the Field Supervisor (see ADDRESSES).
Authors
The primary authors of this final rule are Mr. Andy Roberts (see
FOR FURTHER INFORMATION CONTACT) and Ms. Jennifer Szymanski (U.S. Fish
and Wildlife Service, Whipple Federal Building, 1 Federal Drive, Fort
Snelling, MN 55111-4056).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
record keeping requirements, Transportation.
Regulation Promulgation
Accordingly, we hereby amend part 17, subchapter B of chapter I,
title 50 of the Code of Federal Regulations, as set forth below:
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. Section 17.11(h) is amended by adding the following, in
alphabetical order, under Clams to the List of Endangered and
Threatened Wildlife to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
Clams
* * * * * * *
Mussel, scaleshell............... Leptodea leptodon... U.S.A. (AL, AR, IA, NA................. E 714 NA NA
IL, IN, KY, MN,
MO, OH, OK, SD,
TN, WI).
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dated: September 28, 2001.
Marshall P. Jones, Jr.
Acting Director, Fish and Wildlife Service.
[FR Doc. 01-24804 Filed 10-5-01; 8:45 am]
BILLING CODE 4310-55-P