# Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Five Freshwater Mussels and Threatened Status for Two Freshwater Mussels From the Eastern Gulf Slope Drainages of Alabama, Florida, and Georgia

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URL: https://www.frixlaw.com/law-library/documents/fr%3A98-6493

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** March 16, 1998
- **Citation:** 63 FR 12664

## Text

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AC63

Endangered and Threatened Wildlife and Plants; Determination of
Endangered Status for Five Freshwater Mussels and Threatened Status for
Two Freshwater Mussels From the Eastern Gulf Slope Drainages of
Alabama, Florida, and Georgia

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: The Fish and Wildlife Service (Service) determines five
freshwater mussels, the fat threeridge (Amblema neislerii), shinyrayed
pocketbook (Lampsilis subangulata), Gulf moccasinshell (Medionidus
penicillatus), Ochlockonee moccasinshell (Medionidus simpsonianus), and
oval pigtoe (Pleurobema pyriforme) to be endangered species, and two
freshwater mussels, the Chipola slabshell (Elliptio chipolaensis) and
purple bankclimber (Elliptoideus sloatianus) to be threatened species
under the Endangered Species Act of 1973, as amended (Act). These
mussels are endemic to eastern Gulf Slope streams draining the
Apalachicolan Region of southeast Alabama, southwest Georgia, and north
Florida. Their center of distribution is the Apalachicola-
Chattahoochee-Flint (ACF) River basin of southeast Alabama, southwest
Georgia, and northwest Florida, and the Ochlockonee River system of
southwest Georgia and northwest Florida. They are currently known from
restricted portions of from one to four independent river systems.
These species inhabit stable sandy and gravelly substrates in medium-
sized streams to large rivers, often in areas swept free of silt by the
current. The abundance and distribution of the seven mussel species
decreased historically from habitat loss associated with reservoir
construction, channel construction and maintenance, and

[[Page 12665]]

erosion. These habitat changes have resulted in significant
extirpations (localized loss of populations), restricted and fragmented
distributions, and poor recruitment of young.

DATES: Effective: April 15, 1998.

ADDRESSES: The complete administrative file for this rule is available
for inspection, by appointment, during normal business hours at the
U.S. Fish and Wildlife Service, Jacksonville Field Office, 6620
Southpoint Drive South, Suite 310, Jacksonville, Florida 32216.

FOR FURTHER INFORMATION CONTACT: Dr. Michael M. Bentzien at the above
address, or 904/232-2580, ext. 106.

SUPPLEMENTARY INFORMATION:

Background

Introduction

The fat threeridge, shinyrayed pocketbook, Gulf moccasinshell,
Ochlockonee moccasinshell, oval pigtoe, Chipola slabshell, and purple
bankclimber are freshwater mussels of the family Unionidae found only
in eastern Gulf Slope streams draining the Apalachicolan Region,
defined as streams from the Escambia to the Suwannee river systems, and
occurring in southeast Alabama, southwest Georgia, and north Florida
(Butler 1989). The Apalachicolan Region is known for its high level of
endemicity, harboring approximately 30 species of endemic (found only
in the region) mussels (Butler 1989). The Region drains primarily the
Coastal Plain Physiographic Province. Only the headwaters of the Flint
and Chattahoochee rivers, in the Apalachicola-Chattahoochee-Flint (ACF)
River system, occur above the Fall Line in the Piedmont Physiographic
Province in west-central Georgia.
The decline of some of the species included in this rule was
evident decades ago. The fat threeridge, oval pigtoe, Chipola
slabshell, and purple bankclimber were considered rare, but locally
abundant, in the 1950's (Clench and Turner 1956). The Gulf
moccasinshell, oval pigtoe, and purple bankclimber were recognized in a
list of rare species in 1970 (Athearn 1970), and the fat threeridge was
added to the list of regionally rare mussels a year later (Stansbery
1971a).

General Biology

Freshwater mussel adults are filter-feeders, positioning themselves
in substrates to facilitate siphoning of the water column for oxygen
and food (Kraemer 1979). Their food includes primarily detritus,
plankton, and other microorganisms (Fuller 1974).
As a group, freshwater mussels are extremely long-lived, with life
spans of up to 130 years for certain species (Neves and Moyer 1988,
Bauer 1992). Life spans of these seven species are unknown. Based on
the longevity of a congener of the fat threeridge (the threeridge
[Amblema plicata]; Stansbery 1971b), the longevity of thick-shelled
species (Stansbery 1961), and the large size attained by the fat
threeridge and purple bankclimber (see ``Species Accounts'' in this
section), the latter two species probably have long lifespans.
Freshwater mussels generally have separate sexes. The age of sexual
maturity is variable (Gordon and Layzer 1989), usually requiring from
three (Zale and Neves 1982) to nine (Smith 1979) years, and may be sex
dependent (Smith 1979). Males expel sperm into the water column, while
females draw in the sperm with the in-current water flow (Gordon and
Layzer 1989). Spawning appears to be temperature dependent (Zale and
Neves 1982, Bruenderman and Neves 1993), but may also be influenced by
stream flow (Hove and Neves 1994). Fertilization rates are dependent on
spatial aggregation of reproductive adults (Downing et al. 1993).
Fertilization takes place inside the shell; the fertilized eggs develop
into larvae called glochidia. After an incubation period, mature
glochidia are expelled into the water column and must come into contact
with specific species of fish whose gills and fins they temporarily
parasitize (Gordon and Layzer 1989).
The shinyrayed pocketbook utilizes largemouth bass (Micropterus
salmoides) and spotted bass (M. punctulatus) as primary host fishes.
The latter species appears to have been introduced into the ACF River
system (Lee et al. 1980). The Gulf moccasinshell utilizes the brown
darter (Etheostoma edwini) and blackbanded darter (E. nigrofasciata);
the sailfin shiner (Pteronotropis hypselopterus) serves as the host
fish for the oval pigtoe (O'Brien 1996). Glochidia for the purple
bankclimber transformed on mosquitofish (Gambusia holbrooki) and
blackbanded darter, but these species were not considered by O'Brien
(1996) to be the primary hosts for this mussel.
Host fishes for the fat threeridge, Ochlockonee moccasinshell, and
Chipola slabshell are unknown. The lampsiline Ochlockonee moccasinshell
probably uses darters as host fish, as does its congeners, the Alabama
moccasinshell (Medionidus acutissimus) (W.R. Haag, U.S. Forest Service,
pers. comm.), Cumberland moccasinshell (M. conradicus) (Zale and Neves
1982), and Gulf moccasinshell (O'Brien 1996). Several host fish
families have been identified for the threeridge, a congener of the fat
threeridge, and include eight species of centrarchids (the sunfish
family) (Fuller 1974, Hoggarth 1992). Centrarchids have also been
determined to be fish hosts for species of Elliptio (Fuller 1974,
Hoggarth 1992), and may also serve as host for the Chipola slabshell
and possibly the purple bankclimber, which, genetically, is very
similar to Elliptio spp. (M. Mulvey, Savannah River Ecology Laboratory,
pers. comm.). Minnows (Cyprinidae) may serve as hosts for the fat
threeridge and Chipola slabshell.
The complex life cycle of mussels increases the probability that
weak links in their life history will preclude successful reproduction
and recruitment (Neves 1993). Egg formation and fertilization are
critical phases in the life history; mussels may fail to form eggs
(Downing et al. 1989), or have incomplete fertilization (Matteson
1948). Fertilization success has been shown to be strongly correlated
with spatial aggregation, which either influences the rate of egg
formation, improves fertilization rates of individuals, or both
(Downing et al. 1993).

Status Survey

These seven mussels were considered to be potential candidates for
listing in 1989 (see Previous Federal Actions section). The Service
requested its former National Fisheries Research Center (now the
Florida-Caribbean Science Center of Biological Resources Division of
the U.S. Geological Survey (USGS), subsequently referred to as
``Center'') in Gainesville, Florida, to survey these species in 1991.
The Center surveyed for mussels in both the ACF (324 sites) and
Ochlockonee (77 sites) river systems from 1991 to 1993. Information
gathered during the status survey was summarized by Butler (1993).
Three criteria were used to select status survey sampling sites--(1) to
obtain a thorough and even coverage of the basins, (2) to survey sites
where, based on suitable habitat, there was a maximum chance of finding
one or more of the target species; and (3) to resurvey as many of the
historical sites as possible. The survey was designed to estimate
species distributions and population status, not to determine all
existing populations.
Numerous sites were surveyed in every major river in these
watersheds. Every major tributary was also sampled, and generally at
least one sample was taken on other sizable tributaries in these river
systems. A total of 183

[[Page 12666]]

mainstem, 189 tributary, and 39 reservoir sites were sampled in the ACF
and Ochlockonee River systems. Additional sites were collected in the
Santa Fe River system (Suwannee River system; three sites) and in
Econfina Creek (Bay County, Florida; six sites). Highway bridge
crossings and boat ramps were often used to provide direct access to
sampling sites and to sections of river to be sampled by boat.
The survey technique generally used was hand-picking or grubbing,
which involves a methodical search of the substrate for siphons or
partially exposed specimens, trails, or other signs. Low-visibility
conditions require crawling or lying down on the bottom, and feeling
for shells by running fingers through the substrate. SCUBA and/or
snorkeling were used at about two-thirds of the study sites,
supplemented by hand-picking in shallow water at most sites. Over 95
percent of the collection sites were sampled by four or more people,
spending an average of two hours total effort per sampling site. All
habitat types at each site were sampled for mussels, but efforts
focused on habitats likely to support the target species.
The Center surveyed 150 to 250 meters (m) (492 to 820 feet (ft)) of
a stream reach at most sites. A primary goal was to collect at each
site until there was a high probability that all species occurring
there were found. Small streams were surveyed from bank to bank and
were sampled for longer linear distances than large rivers. Shoals with
high habitat complexity were surveyed more intensively and over longer
distances than slackwater sites with little variation in substrate.
Sites where mussels were uncommon or where only a few common species
were present were sampled for a shorter time and distance. Information
important for establishing baseline mussel population status at each
site was recorded either in the field or during laboratory analyses,
including stream characteristics (e.g., width, depth, water clarity,
substrate), species present, number of live and dead specimens per
species, length of each live mussel, reproductive condition of female
specimens, and condition of dead shells. Most of these specimens were
retained for voucher material, and temporarily stored at the Center in
Gainesville, Florida. After studies unrelated to the status survey are
conducted, the material will be donated to the mollusk collection of an
appropriate museum for curation.
Over 2,300 historical records for mussels in the ACF and
Ochlockonee River systems were also gathered from eight United States
museums with significant mussel holdings. For the purposes of the
survey, a historical collection was any collection made prior to the
status survey (before 1991). Of 300 known historical sites for all
mussel species from the ACF and Ochlockonee River systems, 250 are
identifiable to a specific locality, and 108 harbored one or more of
the seven species. Of the 108 sites with at least one of the species,
100 were in the ACF River system and eight in the Ochlockonee River
system. The ACF River system historical sites include the following--
Flint River system--39 sites, Chipola River system--31 sites,
Chattahoochee River system--20 sites, and Apalachicola River system--10
sites. Additional information on historical mussel populations was
gathered from the scientific literature, unpublished technical reports,
and field records and notes of various collectors.
Previously unknown sites of occurrence for most of the species were
discovered during the status survey in the ACF and Ochlockonee River
systems. The Service believes that historic populations of these
mussels occupied most or all available habitat, and that habitat for
all seven species has declined. The newly discovered sites, therefore,
represent previously unsampled sites. This accounts for the purple
bankclimber being located at more sites during the status survey than
it was known from historically (see ``Species Accounts'' below in this
section). Since mussels are long-lived, these recently discovered
populations have probably existed for at least the past century, as
only a few generations would have elapsed from that time until the
present.

Species Accounts

Fat Threeridge--Amblema Neisleri (Lea, 1858)
The fat threeridge is a medium-sized to large, subquadrate,
inflated, solid, and heavy shelled mussel that reaches a length of 102
millimeters (mm) (4.0 inches (in)). Older, larger individuals are so
inflated that their width approximates their height. The umbos are in
the anterior quarter of the shell. The dark brown to black shell is
strongly sculptured with seven to eight prominent horizontal parallel
ridges. Internally, there are two subequal pseudocardinal teeth in the
left valve and typically one large and one small tooth in the right
valve. The nacre is bluish white to light purplish and very iridescent.
The Service considers Unio neislerii Lea, 1858 to be a synonym of
Amblema neislerii. This taxon was incorrectly assigned to the genera
Quadrula and Crenodonta by Simpson (1914) and Clench and Turner (1956),
respectively. Subsequent investigators (e.g., Turgeon et al. 1988) have
correctly placed the fat threeridge in the genus Amblema.
The fat threeridge was described from the Flint River, Macon
County, Georgia. This species, endemic to the ACF River system,
historically occurred in the mainstems of the Flint, Apalachicola, and
lower Chipola rivers (Clench and Turner 1956, Butler 1993). Clench and
Turner (1956) indicated that this species was generally rare, but
locally abundant. In the Chipola River system, van der Schalie (1940)
reported 17 specimens from two sites (average of 8.5 per site). Clench
and Turner (1956) documented ten to 15 mussels per m (0.9 to 1.4
mussels per ft) square over a 200 m (656 ft) stretch of Dead Lake
(Chipola River) shoreline.
For the status survey, 86 sites were sampled within the historical
range of the fat threeridge, including eight of the 12 (67 percent)
known historical sites. The fat threeridge was found at six of the 86
(7 percent) sampled sites, three each on the Apalachicola and lower
Chipola rivers. Only one of the eight (13 percent) historical sites
still had live individuals. An average of 6.4 live individuals were
found per site.
No live fat threeridge mussels have been found since 1981 in the
Flint River; the species is apparently extirpated from Georgia.
Apparently common in Dead Lake in 1967 (H.G. Lee, amateur malacologist,
pers. comm.), this species was not found live there in 1974 (W.H.
McCullagh, amateur malacologist, pers. comm.), nor during the status
survey.
The smallest live fat threeridge found during the survey was 43 mm
(1.7 in) long. Richardson and Yokley (1996) found evidence of juvenile
fat threeridge at a site in the lower Apalachicola River thought to
have the best extant population of this species (J. Brim Box, USGS,
pers. comm.), where it was the second most common mussel species
encountered. Three fat threeridges under 50 mm (2.0 in) in length were
found employing total substratum removal from six 0.25 m (2.7 ft)
square quadrats. Richardson and Yokley (1996) stated that the smallest
specimens had fewer than the five presumed annual growth rings that
might be indicative of juveniles. A fresh dead individual measured 24
mm (0.9 in) in length and had two to three growth rings. In 1996, three
live specimens ranging from 40 to 50 mm (1.6 to 2.0 in) in length were
located in the same bed (C.A. O'Brien, USGS, pers. comm.). These data

[[Page 12667]]

indicate that the fat threeridge is experiencing limited recruitment at
the site representing its best known population.
Shinyrayed Pocketbook--Lampsilis Subangulata (Lea, 1840)
The shinyrayed pocketbook is a medium-sized species that reaches
approximately 85 mm (3.3 in) in length. The shell is subelliptical,
with broad, somewhat inflated umbos and a rounded posterior ridge. The
shell is fairly thin but solid. The surface is smooth and shiny, light
yellowish brown with fairly wide, bright emerald green rays over the
entire length of the shell. Older individuals may appear much darker
brown with obscure raying. Female specimens are more inflated
postbasally, whereas males appear to be more pointed posteriorly.
Internally, the pseudocardinal teeth are double and fairly large and
erect in the left valve, and one large tooth and one spatulate tooth in
the right valve. The nacre is white, with some individuals exhibiting a
salmon tint in the vicinity of the umbonal cavity. The Service
recognizes Unio subangulatus Lea, 1840 and Unio kirklandianus Wright,
1897 as synonyms of Lampsilis subangulata.
The shinyrayed pocketbook was described from the Chattahoochee
River, Columbus, Georgia. Historically, this mussel occurred in
mainstems and tributaries throughout the ACF River system, and in
larger streams of the Ochlockonee River system (Clench and Turner 1956,
Butler 1993). Van der Schalie (1940) found this species to be generally
rare, but locally abundant, documenting 94 specimens at eight Chipola
River system sites (average of 11.8 per site).
During the status survey, 380 sites within the historical range of
the shinyrayed pocketbook were sampled, including 28 of 54 (52 percent)
known historical sites. Live individuals were found at 23 of the sample
sites, including one site in a Chattahoochee River tributary in
Alabama, 13 sites (12 on tributaries) in the Flint River system, one
locality in the Chipola River, and eight sites (seven mainstem) in the
upper half of the Ochlockonee River system. An average of 2.9 live
individuals were found per site. Live individuals were located at six
(21 percent) of the historical sites. This species has apparently been
eliminated from all but one site in the Chattahoochee River system in
Alabama, and from much of the Chipola River system.
During unrelated studies subsequent to the completion of the status
survey, ten additional sites for the shinyrayed pocketbook were located
in the ACF River system. Eight of these new occurrences were from five
Flint River tributaries; one each occurred in tributaries of the
Chattahoochee and Chipola rivers (Butler and Brim Box 1995, J. Brim
Box, USGS, pers. comm.). The latter two records represent streams where
the species had not been previously collected. The Flint River system
records include one stream where the species had never been collected
(a small tributary of a stream where live specimens were found during
the status survey), and another stream where it was found during the
status survey as a single dead shell; the remaining sites are in
tributaries where it was found live during the status survey.
The smallest shinyrayed pocketbook specimen recorded during the
status survey in the Ochlockonee River system, possibly an older
juvenile, measured 41 mm (1.6 in) in length. In the ACF River system,
the three smallest specimens, measuring 55 to 57 mm (2.17 to 2.24 in)
in length, were gravid females. In 1995, four live, apparently
juvenile, specimens from 30 to 40 mm (1.2 to 1.6 in) in length were
located in a Flint River tributary (C.A. O'Brien, USGS, pers. comm.).
O'Brien (1996) sampled the largest known bed of this species for
juveniles. An 18 m (59.1 ft) by 8 m (26.2 ft) area had 37 adult
shinyrayed pocketbooks (average of 2.1 per m square). Whole substratum
removal of 54 0.25 m (2.7 ft) square quadrats within this bed yielded
no juveniles of this species. The density of shinyrayed pocketbooks at
the four other sites, where quantitative work conducted subsequent to
the status survey yielded specimens, never exceeded 0.08 specimens per
meter square (J. Brim Box, USGS, pers. comm.).
Gulf Moccasinshell--Medionidus Penicillatus (Lea, 1857)
The Gulf moccasinshell is a small mussel that reaches a length of
about 55 mm (2.2 in), is elongate-elliptical or rhomboidal and fairly
inflated, and has relatively thin valves. The ventral margin is nearly
straight or slightly rounded. The posterior ridge is rounded to
slightly angled and intersects the end of the shell at the base line.
Females tend to have the posterior point above the ventral margin and
are somewhat more inflated. Sculpturing consists of a series of thin,
radially-oriented plications along the length of the posterior slope.
The remainder of the surface is smooth and yellowish to greenish brown
with fine, typically interrupted green rays. The left valve has two
stubby pseudocardinal and two arcuate lateral teeth. The right valve
has one pseudocardinal and one lateral tooth. Nacre color is smokey
purple or greenish and slightly iridescent at the posterior end. The
Service recognizes Unio penicillatus Lea, 1857 and Unio kingi Wright,
1900 as synonyms of Medionidus penicillatus.
The recent taxonomic history of Medionidus species in the
Apalachicolan Region is complex. In the Chipola River system, van der
Schalie (1940) recorded two species of Medionidus--M. kingi and M.
penicillatus. Clench and Turner (1956) synonymized M. kingi and two
other nominal species, the Ochlockonee moccasinshell and Suwannee
moccasinshell (M. walkeri [Wright, 1897]) under the Gulf moccasinshell,
an arrangement also followed by Burch (1975). Johnson (1970)
erroneously reported both the Gulf moccasinshell and Suwannee
moccasinshell from the ACF River system and the Suwannee moccasinshell
from the Ochlockonee and Suwannee rivers as well. Johnson (1977)
recognized the validity of the Gulf moccasinshell, Ochlockonee
moccasinshell, and Suwannee moccasinshell from Apalachicolan Region
streams based on shell characters. The validity of the three
allopatrically distributed Apalachicolan Region Medionidus species is
also recognized by Turgeon et al. (1988).
The Gulf moccasinshell was described from three sites in the ACF
River system in Georgia--the Chattahoochee River near Columbus and near
Atlanta, and the Flint River near Albany. The historical ACF River
system distribution included tributaries and mainstems of the Flint,
Chattahoochee, and Chipola rivers, and the mainstem Apalachicola River.
More western localities in the Apalachicolan Region included Econfina
Creek (Bay County, northwest Florida), the Choctawhatchee River system,
and the Yellow River (Johnson 1977; Butler 1989, 1993). Clench and
Turner (1956) considered this species rare, but locally abundant. Van
der Schalie (1940) reported 166 specimens from 11 sites, including 130
from two sites in the Chipola River system, an average of 15.1 per
site.
During the status survey, 330 sites within the historic range of
the Gulf moccasinshell were sampled, including 13 of 31 (42 percent)
known historical sites. This species was found at eight sites (two
percent), including only one of the historical sites. It was found at
seven sites (including one mainstem site) in the middle Flint River
system, and at one Econfina Creek site. An average of 1.4 live
individuals was

[[Page 12668]]

found per site. All Alabama populations of the Gulf moccasinshell
appear to be extirpated, and no specimens were found in the Chipola
River system during the status survey. The species has not been
collected in the Choctawhatchee River system since the early 1930's and
in the Yellow River since 1963 (Williams and Butler 1994).
Six new sites for the Gulf moccasinshell from tributaries of the
ACF River system were found subsequent to the status survey (Butler and
Brim Box 1995, J. Brim Box, USGS, pers. comm.). Three sites were
streams from which this species had never been found (one tributary
each in the Chattahoochee, Flint, and Chipola rivers), two were streams
(both Flint River system) where this species was found live during the
status survey, and one site was a stream in the Chattahochee River
system where a single dead shell had been located during the status
survey.
Densities of Gulf moccasinshells at two sites where quantitative
work was conducted were under 0.4 specimens per meter square (J. Brim
Box, USGS, pers. comm.). All specimens located during and subsequent to
the status survey were adults; no specimens less than 50 mm (2.2 in)
were located.
Ochlockonee Moccasinshell--Medionidus Simpsonianus Walker, 1905
The Ochlockonee moccasinshell is a small species, generally under
55 mm (2.2 in) in length. It is slightly elongate-elliptical in
outline, the posterior end obtusely rounded at the shell's median line
and the ventral margin broadly curved. The posterior ridge is
moderately angular and covered in its entire length with well
developed, irregular ridges. Sculpture may also extend onto the disk
below the ridge. Surface texture is smooth. The color is light brown to
yellowish green, with dark green rays formed by a series of connected
chevrons or undulating lines across the length of the shell. Internal
characters include thin straight lateral teeth and compressed
pseudocardinal teeth. There are two laterals and two pseudocardinals in
the left valve and one lateral and one pseudocardinal in the right
valve. The nacre is bluish white. A summary of the taxonomic history of
the genus Medionidus follows the Gulf moccasinshell description above.
The Ochlockonee moccasinshell was described from the Ochlockonee
River, Calvary, Grady County, Georgia. This Ochlockonee River system
endemic was known historically from the mainstem and the Little River
(Johnson 1977, Butler 1993). Museum records for this species sometimes
numbered in the dozens of individuals at sites above Talquin Reservoir.
During the status survey, eight sites were sampled within the
historic range of the Ochlockonee moccasinshell, including three of six
(50 percent) known historical sites. Live individuals were found at two
sites (one specimen at each site); one of these was a historic site.
Another specimen was located in 1995 (J. Brim Box, USGS, pers. comm.)
at a site previously sampled during the status survey. Only three live
individuals are known to have been collected since 1974 despite
concerted efforts by numerous investigators; none were juveniles.
Oval Pigtoe--Pleurobema Pyriforme (Lea, 1857)
The oval pigtoe is a small to medium-sized species that attains a
length of about 60 mm (2.4 in). The shell is suboviform compressed,
with a shiny smooth epidermis. The periostracum is yellowish, chestnut,
or dark brown, rayless, and with distinct growth lines. The posterior
slope is biangulate and forms a blunt point on the posterior margin.
The umbos are slightly elevated above the hingeline. As is typical of
the genus, no sexual dimorphism is displayed in shell characters.
Internally, the pseudocardinal teeth are fairly large, crenulate, and
double in both valves. The lateral teeth are somewhat shortened,
arcuate, and double in each valve. Nacre color varies from salmon to
bluish white and is iridescent posteriorly. Variation in this species
has led to the description of various nominal species. The Service
currently recognizes Unio pyriformis Lea, 1857, Unio modicus Lea, 1857,
Unio bulbosus Lea, 1857, Unio amabilis Lea, 1865, Unio reclusum Wright,
1898, Unio harperi Wright, 1899, and Pleurobema simpsoni Vanatta, 1915
as synonyms of Pleurobema pyriforme.
The oval pigtoe was described from the Chattahoochee River, near
Columbus, Georgia. Historically, this species was one of the most
widely distributed and common mussels endemic to the Apalachicolan
Region. It occurred throughout the mainstems and several tributaries of
both the Flint and Chipola River systems, in the lower Chattahoochee
River mainstem and several of its tributaries, in the Apalachicola
River mainstem, and in the upper portion of the Ochlockonee River
system. The oval pigtoe was also known from a single Suwannee River
mainstem site and the confluent Santa Fe River system, and in Econfina
Creek (Clench and Turner 1956, Butler 1993). Once a species of
localized abundance (Clench and Turner 1956), oval pigtoe populations
sometimes numbered in the hundreds (van der Schalie 1940). In the
Chipola River system, van der Schalie (1940) reported 470 specimens
from 9 sites (an average of 52.2 per site).
During the status survey, 410 sites were sampled within the
historic range of this species, including 20 of 50 (40 percent) known
historical sites. The oval pigtoe was found at 24 (6 percent) of the
sample sites, including seven of the historic sites, with an average of
5.2 live individuals per site. The species was found at one mainstem
site and seven tributary sites in the Flint River system, six mainstem
Chipola River sites, six mainstem sites and one tributary site in the
upper Ochlockonee River system, one site in the New River (upper Santa
Fe River system), and two sites in Econfina Creek. The oval pigtoe has
apparently been extirpated from the Chattahoochee River system in
Alabama and much of the Chipola River system.
Subsequently, five new occurrences of the oval pigtoe were located
in three ACF River system tributaries. One occurrence was from a stream
in the Chipola River system not previously known to have harbored this
species. The other four occurrences were in two streams (two sites in
each stream), that are tributaries to the Chattahoochee and Flint
rivers where the species had been recorded during the status survey
(Butler and Brim Box 1995; J. Brim Box, USGS, pers. comm.).
Oval pigtoe density at the five new sites never exceeded 0.4
specimens per meter square (J. Brim Box, USGS, pers. comm.). The
smallest individual collected during or subsequent to the status survey
was 26 mm (1.0 in) in length, indicating that juveniles were not
present in these collections.
Chipola Slabshell--Elliptio Chipolaensis Walker, 1905
The Chipola slabshell is a medium-sized species reaching a length
of about 85 mm (3.3 in). The shell is ovate to subelliptical, somewhat
inflated and with the posterior ridge starting out rounded, but
flattening to form a prominent biangulate margin. The surface is smooth
and chestnut colored. Dark brown coloration may appear in the umbonal
region and the remaining surface may exhibit alternating light and dark
bands. The umbos are prominent, well above the hingeline. Internally,
the umbonal cavity is rather deep. The lateral teeth are long, slender,
and slightly curved; two in the left and one in the right valve. The
pseudocardinal teeth are compressed and crenulate; two in the left and
one in the right valve. Nacre color is salmon, becoming more

[[Page 12669]]

intense dorsally and somewhat iridescent posteriorly.
The Chipola slabshell was described from the Chipola River,
Florida. Clench and Turner (1956) restricted the type locality to the
Chipola River, 1.6 km (1.0 mi) north of Marianna, Jackson County,
Florida. This species was considered to be a Chipola River system
endemic, occurring in the mainstem from the vicinity of Dead Lake
upstream and in a few of its larger tributaries, all in Florida (van
der Schalie 1940, Clench and Turner 1956). However, a historical record
recently brought to light has been verified from a small tributary of
the Chattahoochee River in extreme southeast Alabama (Butler 1993). Van
der Schalie (1940) documented 31 specimens from six sites in the
Chipola River system (an average of 5.2 per site).
During the status survey, 33 sites within the historical range of
this species on the Chipola River were sampled, including 12 of 16 (75
percent) known historical sites. Live individuals were found at five
sites (15 percent), including one historical site. An average of 3.7
live individuals was found per site. Live individuals were located at
one of the 12 historic resurveyed sites. Populations from Spring Creek
(middle Chipola River system) and the Chattahoochee River system
apparently have been extirpated, with the latter loss resulting in the
extirpation of the Chipola slabshell from Alabama.
No live specimens appeared to be juveniles, as the smallest live
individual was 47 mm (1.9 in) in length. The Chipola slabshell has one
of the most restricted ranges of any Apalachicolan Region mussel.
However, it appears to be more tolerant of soft sediments than other
species included in this rule, has potentially more habitat available
than channel-dwelling species, and may co-occur with more silt-tolerant
species in stream bank habitats with slower currents.
Purple Bankclimber--Elliptoideus Sloatianus (Lea, 1840)
The purple bankclimber is a large, heavy-shelled, strongly
sculptured mussel reaching lengths of 200 mm (8.0 in). A well-developed
posterior ridge extends from the umbos to the posterior ventral margin
of the shell. The posterior slope and the disk just anterior to the
posterior ridge are sculptured by several irregular ridges that vary
greatly in development. Umbos are low, extending just above the dorsal
margin of the shell. Internally, there is one pseudocardinal tooth in
the right valve and two in the left valve. The lateral teeth are very
thick and slightly curved. Nacre color is whitish near the center of
the shell becoming deep purple towards the margin, and very iridescent
posteriorly. The Service recognizes Unio sloatianus Lea, 1840, Unio
atromarginatus Lea, 1840, Unio aratus Conrad, 1849, and Unio
plectophorus Conrad, 1950 as synonyms of Elliptoideus sloatianus.
Elliptoideus sloatianus was included in the genus Elliptio until
Frierson (1927) erected the subgenus Elliptoideus based on the presence
of glochidia in all four gills instead of two gills, a characteristic
of the genus Elliptio. Clench and Turner (1956) overlooked the work of
Frierson (1927), placing the species under Elliptio. Subsequent
investigators (e.g., Turgeon et al. 1988) have correctly assigned this
species to the monotypic genus Elliptoideus.
The purple bankclimber was described from the Chattahoochee River
in Georgia. The type locality was restricted to the Chattahoochee River
at Columbus, Georgia, by Clench and Turner (1956). In the ACF River
system, the purple bankclimber was historically found throughout the
mainstem and in a few of the largest tributaries in the Flint River
system, in the vicinity of Dead Lake on the lower Chipola River
mainstem (although not reported by van der Schalie (1940)), and along
the mainstems of the Apalachicola and Chattahoochee rivers. The species
occurred in the lower two-thirds of the mainstem of the Ochlockonee
River, and in the Little River (Clench and Turner 1956, Butler 1993).
During the status survey, 222 sites were sampled within the
historic range of the purple bankclimber, including 14 of 27 (53 per
cent) known historic sites. Live individuals were found at 41 (18
percent) sites, with an average of 54 individuals per site. The purple
bankclimber was found at six of the 14 historical sites. The species
was found at 17 mainstem sites and one tributary site on the lower two-
thirds of the Flint River, at five sites in the Apalachicola River, and
at 18 sites on the Ochlockonee River mainstem, mostly above Talquin
Reservoir. Having been extirpated from the Chipola and Chattahoochee
rivers, no extant populations occur in Alabama. Its range in the Flint
and Ochlockonee River systems also has been reduced.
It is uncertain if purple bankclimber populations are successfully
recruiting young. Two specimens <70 mm (2.8 in) in length were
collected from the Ochlockonee River during the survey; they were 53 mm
(2.1 in) and 59 mm (2.3 in) in length. Based upon the large size
attained by this species, both were possibly juveniles. The smallest
specimen found during the survey in the ACF River system was 76 mm (3.0
in) in length, a size that possibly represents a juvenile. Richardson
and Yokley (1996) took six 0.25 meter (2.7 ft) square total substratum
removal quadrat samples at a site below Jim Woodruff Dam in the
Apalachicola River where the purple bankclimber was abundant, being the
second most commonly encountered species. No specimens smaller than 133
mm (5.2 in) were found, indicating a lack of recruitment at this site.
Previous Federal Action
The fat threeridge, shinyrayed pocketbook, oval pigtoe, and purple
bankclimber first appeared as category 2 species in the Service's
notices of review for animal candidates that were published on January
6, 1989 (54 FR 554) and on November 21, 1991 (56 FR 58804). At that
time, a category 2 species was one that was being considered for
possible addition to the Federal List of Endangered and Threatened
Wildlife. Designation of category 2 species was discontinued in the
February 28, 1996, Federal Register notice (61 FR 7596) (see also Issue
103 in the ``Summary of Comments and Recommendations'' section). The
Service determined that these four species plus the Gulf moccasinshell,
Ochlockonee moccasinshell, and Chipola slabshell qualified as candidate
species at the time of proposal for listing. A candidate species is a
species for which the Service has sufficient information to propose it
for protection under the Act. All seven species have been recommended
for conservation status by Williams et al. (1992a) and Williams and
Butler (1994).
On November 18, 1993, the Service notified by mail (72 letters)
potentially affected Federal and State agencies, local governments, and
interested individuals that a status review was being conducted for
these seven species. Ten comments were received. The Florida Division
Office of the Federal Highway Administration stated that no bridge
replacement projects were currently planned in northwest Florida, and
that any future bridge replacement projects were not anticipated to
affect these species, based on the localized and short-term impacts
associated with these activities. The Federal Energy Regulatory
Commission stated that they license twelve hydroelectric developments
in the study area, and that issues concerning these species should be
coordinated with the Office of Hydropower Licensing. The Fayette
County, Georgia, Board of Commissioners expressed concern with the
Service's belief that impoundments

[[Page 12670]]

had played such a major role in the demise of these species. The
Alachua County, Florida, Environmental Protection Department indicated
that none of the seven species were known or suspected to occur in that
county. The Florida Game and Fresh Water Fish Commission expressed
concern with how their plan to dredge the mouths of several silted in
streams along the Apalachicola River to improve access for striped bass
(Morone saxatilis) might affect these mussels. The Georgia Department
of Natural Resources had questions concerning the distribution of these
mussels, and sent a copy of regulations addressing the commercial
harvest of mussels in Georgia. The Florida Natural Areas Inventory
supported Federal listing of these species, and indicated that a
portion of the Econfina Creek watershed where the Gulf moccasinshell
and oval pigtoe occur is on a list for land purchase by the State of
Florida. Three individuals with knowledge of freshwater mussels
supported Federal listing of these species.
The processing of this final rule conforms with the Service's final
listing priority guidance published in the Federal Register on December
5, 1996 (61 FR 64475). The guidance clarifies the order in which the
Service will process rulemakings during fiscal year 1997. The guidance
calls for giving highest priority to handling emergency situations
(Tier 1) and second highest priority (Tier 2) to resolving the listing
status of the outstanding proposed listings. This rule falls under Tier
2. Presently, there are no pending Tier 1 actions in Region 4 and this
is the Region's last outstanding Tier 2 action. Additionally, the
guidance states that ``effective April 1, 1997, the Service will
concurrently undertake all of the activities presently included in
Tiers 1, 2, and 3'' (61 FR 64480). In a Federal Register notice
published on October 23, 1997 (62 FR 55628), the guidance was extended
beyond FY 1997 until such time as new guidance is published.
In the development of this final rule, the Service has conducted an
internal review of a draft of this rule and other Service-generated
information. Based on this review, the Service has determined that
there is no new information that would substantively affect these
listing decisions and that additional public comment is not warranted.

Summary of Comments and Recommendations

In the August 3, 1994, proposed rule (59 FR 39524), and through
associated notifications, all interested parties were requested to
submit factual reports and information that might contribute to the
development of a final rule. Appropriate Federal and State agencies,
county governments, scientific organizations, and interested parties
were contacted by letter dated August 18, 1994, and were requested to
comment. Legal notices were published in the following newspapers--the
Albany Herald, Albany, Georgia, on August 20, 1994; the Atlanta
Journal-Constitution, Atlanta, Georgia, on August 21, 1994; the
Columbus Ledger-Enquirer, Columbus, Georgia, on August 21, 1994; the
Macon Telegraph, Macon, Georgia, on August 20, 1994; the Thomasville
Times-Enterprise, Thomasville, Georgia, on August 19, 1994; The
Gainesville Sun, Gainesville, Florida, on August 18, 1994; the Jackson
County Floridan, Marianna, Florida, on August 21, 1994; the Tallahassee
Democrat, Tallahassee, Florida, on August 21, 1994; and The News-
Herald, Panama City, Florida, on August 22, 1994.
In response to twelve formal requests during the first public
comment period, the Service scheduled five public hearings in the
three-State area within the historical range of these seven species.
Prior to the hearings, the Service held five public informational
meetings at the same sites as the public hearings. A notice of public
meetings, public hearings, and reopening of the comment period was
published in the Federal Register on December 12, 1994 (59 FR 63987),
and in legal notices in the following newspapers--the Albany Herald,
Albany, Georgia on January 6, 1995; The Atlanta Journal-Constitution,
Atlanta, Georgia on January 8, 1995; the Columbus Ledger-Enquirer,
Columbus, Georgia on January 5, 1995; the Dothan Eagle, Dothan, Alabama
on January 7, 1995; the Montgomery Advertiser, Montgomery, Alabama on
January 5, 1995; the Tallahassee Democrat, Tallahassee, Florida on
January 6, 1995; the Jackson County Floridan, Marianna, Florida on
January 8, 1995; and the Fayette News, Fayetteville, Georgia, on
January 11, 1995. The comment period for the proposal closed on
February 10, 1995.
Public meetings were held at the Fayette County High School in
Fayetteville, Georgia on January 5, 1995; at Chipola Junior College in
Marianna, Florida on January 9, 1995; at the Opera House in Dothan,
Alabama on January 10, 1995; at the Albany Civic Center in Albany,
Georgia on January 11, 1995; and at the Convention and Trade Center in
Columbus, Georgia on January 12, 1995. Public hearings were held at the
same facilities in Fayetteville, Georgia on January 19, 1995; Dothan,
Alabama on January 23, 1995; Marianna, Florida on January 24, 1995;
Albany, Georgia on January 25, 1995; and Columbus, Georgia, on January
26, 1995.
In a Federal Register notice dated April 24, 1995 (60 FR 20072),
the Service reopened the comment period on this proposal until May 5,
1995, to allow for consideration of numerous comments received after
the previous deadline (February 10, 1995) and to provide an opportunity
for further comment. Legal notices were published in the following
newspapers--the Albany Herald, Albany, Georgia on April 21, 1995; The
Atlanta Journal-Constitution, Atlanta, Georgia on April 24, 1995; the
Columbus Ledger-Enquirer, Columbus, Georgia on April 21, 1995; the
Dothan Eagle, Dothan, Alabama on April 26, 1995; the Montgomery
Advertiser, Montgomery, Alabama on April 22, 1995; the Tallahassee
Democrat, Tallahassee, Florida on April 23, 1995; the Jackson County
Floridan, Marianna, Florida on April 26, 1995; and the Fayette News,
Fayetteville, Georgia on April 26, 1995.
During the April 10, 1995, to April 26, 1996, listing moratorium,
studies involving some of these proposed species were conducted in the
ACF River system. To accept this new information, the Service published
a notice in the Federal Register (61 FR 36020) on July 9, 1996,
reopening the comment period until July 26, 1996. Legal notices were
published in the following newspapers--the Albany Herald, Albany,
Georgia on July 14, 1996; The Atlanta Journal-Constitution, Atlanta,
Georgia on July 17, 1996; the Columbus Ledger-Enquirer, Columbus,
Georgia on July 14, 1996; the Dothan Eagle, Dothan, Alabama on July 14,
1996; the Montgomery Advertiser, Montgomery, Alabama on July 14, 1996;
the Tallahassee Democrat, Tallahassee, Florida on July 14, 1996; the
Jackson County Floridan, Marianna, Florida on July 14, 1996; and the
Fayette News, Fayetteville, Georgia on July 14, 1996.
The Service received hundreds of written comments and many oral
statements presented at the public hearings and received during the
comment periods. All pertinent comments have been considered in the
formulation of this final rule. The proposed listings were supported by
the U.S. Forest Service, the Environmental Protection Agency (EPA), and
the States of Alabama (Department of Conservation and Natural
Resources) and Florida (Department of Environmental Protection and Game
and Fresh Water Fish Commission [FGFWFC]). The congressional
delegations of the three States opposed the proposed listings. The
following is

[[Page 12671]]

a summary of the comments, concerns, and questions (referred to as
``Issues'' for the purposes of this summary) and the Service's response
to each. Comments of similar content have been grouped together.
Issue 1: Numerous commenters thought that the status survey was
insufficient to make listing determinations for these seven species.
Issues of concern included sampling methodologies, specimens collected,
sites sampled, interpretation of historical data, whether sampling for
juveniles had been adequate, and evidence of recent reproduction and
recruitment. Other issues raised included the need for quantitative
sampling, the percentage of historical sites sampled, how historical
sites were selected for sampling, the evidence for the decline of these
species, whether newly discovered sites represented new colonization by
these mussels, and the reproductive viability of remaining populations.
Response: Explanations of sampling methodology, specimens
collected, sites sampled, and analysis of historical data have been
included under ``Status Survey'' and ``Species Accounts'' in the
Background section. Other issues associated with the status survey are
discussed below.
Quantitative sampling is not essential to determine the status of
rare riverine mussel species (Miller and Payne 1988). Mussel
populations are often distributed non-randomly (Downing and Downing
1992). Even where habitats appear to be uniform, mussels tend to be
distributed unevenly (Downing 1991). For these reasons, random
transect-type quantitative sampling is less efficient than choosing
sites based on criteria such as available habitat (G.L. Warren, FGFWFC,
in litt. 1995).
The Service compiled 300 historical site records from the ACF and
Ochlockonee River systems; 108 of these sites had records of one or
more of these proposed species. Research into historical mussel
collections since the status survey was completed has yielded
additional historical sites not reported in Butler (1993). The
percentage of historical sites in the ACF and Ochlockonee River systems
resurveyed for the seven species during the status survey ranged from
40 to 75 percent, while the percentages of resurveyed historical sites
in the ACF and Ochlockonee River systems that still supported live
specimens of the seven species ranged from eight to 43 percent.
Detailed analyses of these data are presented under ``Status Survey''
and ``Species Accounts'' in the ``Background'' section. Many historical
sites had been visited more than once by other researchers or
collectors prior to the status survey. If evidence indicated the
species had disappeared from a historical site, and there was little
probability of currently finding it, survey efforts were not expended
there.
The Service believes the newly discovered sites do not represent
newly colonized sites, but sites that have existed historically but
have not been previously sampled by collectors (see ``Status Survey''
under Background).
The fat threeridge, shinyrayed pocketbook, Gulf moccasinshell, and
oval pigtoe were historically considered rare, but widespread and
locally abundant (Clench and Turner 1956). Mussel populations were
decimated in the Chattahoochee River in the vicinity of Columbus,
Georgia, by the early part of this century (Clench and Turner 1956).
The river-dependent mussel species along the entire Chattahoochee River
mainstem now appear to be extirpated (Butler 1993).
Determination of sexual maturity in these species would require
sectioning to locate mature gametes; determining age would require
sectioning the shells (Neves and Moyer 1988); this was not within the
scope or intent of the status survey. The Service considered shells to
represent juveniles if they were less than one-quarter of the maximum
size for each species. Based on the adult sizes typical of these seven
mussel species, very few juvenile specimens were located during the
status survey. While substrate samples were not taken, the survey
biologists located thousands of smaller species of bivalves and snails.
These included the ubiquitous Asian clam (Corbicula fluminea),
pleurocerid (Elimia spp.) and other snails, and the iridescent lilliput
(Toxolasma paulus), a mussel species rarely exceeding 32 mm (1.25 in)
in total length. The Service believes that if significant recruitment
was occurring in the seven species, more juvenile and small shells
would have been located.
Juveniles were also represented in some museum collections.
Specimens of purple bankclimber as small as 26 mm (1.0 in) in length
were represented in museum collections while the smallest specimen
located during the status survey was 53 mm (2.1 in). The occurrence of
juvenile specimens in museum collections substantiated population
viability and indicated recent reproduction at the time the historical
collection was made.
Richardson and Yokley (1996) employed total substratum removal of
six 0.25 m (2.7 ft) quadrats at each of three sites. They found three
juvenile individuals of the fat threeridge in the lower Apalachicola
River, but no evidence of recruitment of the purple bankclimber below
Jim Woodruff Dam on the same river. These two species were both common
and represented the second most abundant species at their respective
sites. The fat threeridge population sampled is the largest known (J.
Brim Box, USGS, pers. comm.). These data indicate that the fat
threeridge is experiencing limited recruitment, but that there is no
evidence of recruitment in the purple bankclimber at these sites.
Brim Box and Dorazio (in press) took 2,867 substrate core samples
(representing a composite 4.23 m (45.5 ft) square) for mussels at 30
sites in the ACF system. No specimens of any of the 7 species in this
rule were located in the 2,867 core samples, although juveniles of a
few common species were found. Brim Box and Dorazio (in press) also
took 2,867 0.25 m (2.7 ft) square quadrat samples, without total
substratum removal, for mussels. No juveniles of the seven species were
found.
Richardson and Yokley (1996) stated that their work demonstrated
that unequivocal evidence of recruitment can be found with minimal
sampling effort. However, most literature on this subject demonstrates
that the collection of juveniles is a low probability event (Kat 1982,
Neves and Widlak 1987, Stansbery 1995). Quadrat sampling has
consistently been determined to be inadequate for rare species (Neves
et al. 1980, Kovalak et al. 1986, Neves and Odum 1989). The extreme
patchiness of mussel distributions makes quantitative surveys
expensive, time consuming, and not the best method to determine the
population status of rare species (Miller and Payne 1988). The large
number of substratum samples necessary to confirm recent recruitment is
also disruptive to the stable benthic habitat essential to these and
other riverine species (A.E. Bogan, North Carolina State Museum, pers.
comm.).
Issue 2: Several commenters said that the author of the proposed
rule stated in a published paper that major portions of the
Apalachicola and Ochlockonee rivers were ``virtually unsurveyed.''
Response: What that statement referred to was that few historical
sampling sites existed on the Apalachicola and lower Ochlockonee rivers
at that time (Butler 1989). Subsequent surveys on the Apalachicola (35
sites) and Ochlockonee River (24 sites) mainstems have provided
adequate information to evaluate the status of the species considered
in this rule.
Issue 3: A few respondents asserted that comparing historical
survey sites

[[Page 12672]]

with status survey sites is difficult because of differing collection
techniques and the dynamic nature of streams (what was suitable habitat
decades ago could now be very unsuitable due to various factors). One
commenter urged the Service to use collection methods employed by early
collectors to thoroughly sample streams.
Response: The Service agrees that there may have been changes in
habitat suitability over time. To compensate for this factor, Center
biologists surveyed upstream and downstream of historical sites. While
streams are dynamic, the proportions of riffle, run, and pool habitats
remain fairly constant. Based on human influences over the past two
centuries, the Service believes that available habitat for these
mussels has diminished significantly (see Factor A in the ``Summary of
Factors Affecting the Species'' section).
Issue 4: One malacologist (mussel expert) asked if it would be
possible to time-code the map symbols in the status survey report so
that the distribution found in this study could be distinguished from
that of earlier collections.
Response: The distributional data could be time-coded; however,
time-coding collections was not essential to determine the status of
the seven mussels.
Issue 5: Two malacologists suggested that some of these species
have always been rare according to the literature, and that population
declines could not be proven. One respondent questioned how many of the
species existed historically compared to now.
Response: Van der Schalie (1940) gathered data on Chipola River
mussels from collections taken between 1915 to 1918 and included actual
numbers of mussels from various sites in the drainage. A comparison of
this historical data with the status survey results indicates a
significant reduction in the numbers of at least two species in the
Chipola River. Historically, 470 oval pigtoe specimens were collected
from nine sites (an average of 52 per site) in the Chipola River versus
35 specimens collected from six sites (an average of six per site)
during the status survey. Historically, 166 specimens of the Gulf
moccasinshell were known taken from eleven sites (an average of 15 per
site) versus no specimens collected in the status survey.
Clench and Turner (1956) indicated that some species (e.g., the fat
threeridge and oval pigtoe) were rare and only locally abundant. They
documented 10 to 15 specimens/meter (0.9 to 1.4 specimens/ft) square of
fat threeridge over a 200 m (656 ft) stretch of Dead Lake (Chipola
River). The fat threeridge apparently disappeared over 20 years ago in
Dead Lake and was not found live there during the status survey. Except
for the purple bankclimber, which is abundant at a few sites, these
species are now rare range-wide and are not abundant at any known sites
(see ``Species Accounts'' in the ``Background'' section).
Issue 6: Two respondents stated that Federal listing of the purple
bankclimber was not warranted because the species was abundant at some
sites in the lower Flint and upper Ochlockonee rivers. One of these
individuals further stated that he was confident that juveniles of this
species were common.
Response: The purple bankclimber is the most abundant of the seven
mussels; however, no additional information on purple bankclimber
abundance or recruitment was provided to the Service by these
commenters. Recent sampling efforts on the Apalachicola River
(Richardson and Yokley 1996) located only large individuals, indicating
a lack of recruitment in this species.
Issue 7: One commenter indicated that the Gulf moccasinshell still
exists at several sites in the Chipola River system.
Response: Van der Schalie (1940) reported 166 Gulf moccasinshells
taken from eleven sites (an average of 15 specimens per site) in the
Chipola River system, but none were located during the status survey.
The Service received information on a recently discovered population in
Baker Creek, in the Chipola River system, after publication of the
proposal (see ``Species Accounts'' in the ``Background'' section), but
the commenter provided no specific location or other information.
Issue 8: Several commenters questioned the Service's statements
regarding impoundments, including status survey efforts in
impoundments, impact of impoundments upon these species, and the purple
bankclimber's tolerance of impoundments.
Response: Much riverine habitat in the ACF system has been
converted to slack-water impoundments, particularly in the
Chattahoochee River; however, verifiable pre-impoundment records of
these species are uncommon (see Factor A in the ``Summary of Factors
Affecting the Species'' section). Museum records confirm that some of
the Ochlockonee River mussel fauna was inundated and lost at the upper
end of Talquin Reservoir. Many historical collections came from the
Chattahoochee River in the vicinity of Columbus, Georgia. Although
exact locality data is generally lacking, several impoundments in this
reach of river permanently reduced available riverine habitat for
mussels.
During the status survey, 39 reservoir sites were surveyed; none of
the seven species were found in permanently impounded river reaches.
None of these species are known to successfully reproduce and recruit
under impoundment conditions. The reference to the purple bankclimber's
tolerance of impounded conditions was based on a mussel relocation
project funded by the U.S. Army Corps of Engineers (Corps). Purple
bankclimbers from the Apalachicola River survived twelve months in
laboratory tanks at the USGS research facility in Gainesville, Florida
(Hamilton et al. 1996). However, the mussels were maintained in flow-
through tanks with currents. The experiment does not indicate that the
purple bankclimber can survive and reproduce under impounded
conditions.
Issue 9: Two commenters questioned the expertise of the Center
biologists who carried out the status survey.
Response: The project leader of the status survey has 20 years
experience with mussel research and surveys. The field leader has an
M.S. degree in aquatic sciences and seven years field experience in
aquatic biology. Field biologists, with one exception, had education in
aquatic biology ranging from the B.S to Ph.D. level. Two scientists
associated with the project have published scientific papers on mussel
surveys and endangered species. The Service believes that all
individuals involved in the survey were well qualified.
Issue 10: One commenter questioned the adequacy of the sampling
done by the status survey biologists, noting that various status survey
field notes (e.g., the water was too cold, too turbid, or too deep)
indicated that sampling was inadequate and that portions of the field
data should be discarded.
Response: The survey biologists employed the most appropriate
sampling techniques based upon the habitat conditions present at each
site. When high water precluded sampling, sites were usually revisited
in lower water conditions to sample. The Service believes that the
information gathered during field work is reliable and supports the
determinations made in this rule.
Issue 11: One commenter assumed that when the survey biologists
checked a mussel for the presence of mature glochidia the mussel was
stressed or even killed. Another respondent questioned the Service's
recording of laboratory data, noting that an entire collection of over
one hundred

[[Page 12673]]

individuals of a common species was comprised of all females.
Response: During the status survey, some voucher mussels were
preserved and brought to the laboratory for analysis, including
inspection for glochidia. Most of the specimens were returned unharmed
to the substrate from which they were collected. The species referred
to by the respondent as consisting of only females were members of the
genus Elliptio. This genus does not exhibit obvious external
differences between the sexes; glochidia must either be present or
gonadal tissues sectioned to determine sex. Laboratory notes on this
collection stated that glochidia were not present (or ``NP'' on the
data sheets) for any individual. The commenter apparently misconstrued
``NP'' as meaning ``female, glochidia not present.'' Although their sex
could not be determined, it is likely that both sexes were represented
in the sample.
Issue 12: Some respondents contended that the Service had not
sampled the Escambia, Yellow, and Choctawhatchee rivers, where there
were historical records of two of these species.
Response: There is one historical record of the Gulf moccasinshell
in the Yellow River (1963) and four records from the Choctawhatchee
River in the 1930's. The Service examined over 30 collections taken
from these watersheds over the past few decades. The Gulf moccasinshell
did not occur in any of these collections. The Service believes this
species is extirpated from the Yellow and Choctawhatchee River systems.
Clench and Turner (1956) confused the shinyrayed pocketbook with
the southern sandshell (Lampsilis australis) and erroneously stated
that the shinyrayed pocketbook's range included the Choctawhatchee
River. Johnson (1970), Heard (1979), and Williams and Butler (1994)
clarified the range of the shinyrayed pocketbook as comprising only the
ACF and Ochlockonee River systems. There are no records of any of the
seven species from the Escambia River system. Collections made by the
Center between 1993 and 1995 in this drainage corroborate this
information.
Issue 13: One respondent commented that the Service's diving
regulations precluded divers from collecting in navigable river
channels, thus making it impossible to assess mussel populations there.
Response: Service diving regulations do not preclude sampling in
navigable channels. Many dives using SCUBA were made in navigable
channels during the status survey, and the Service believes that mussel
populations in such areas were adequately sampled.
Issue 14: One commenter stated that $27,000 was not adequate to
conduct the status survey for the seven proposed mussels.
Response: The Service's Jacksonville, Florida, Field Office
provided $27,000 in initial funding and $12,000 during the survey.
Total expenditures for the status survey were over $110,000. The
Service believes the status survey was adequate to determine the status
of these species.
Issue 15: Various commenters were concerned that the scientific
data associated with the status survey were not subjected to proper
peer review.
Response: The information supporting these determinations was
extensively peer reviewed according to Service policy (see paragraph
following the Service's response to Issue 107 in the ``Summary of
Comments and Recommendations'' section for a discussion of peer
review).
Issue 16: Several respondents stated that any decision to list
these species should be deferred until data is available on habitat
requirements, fish hosts, and threats to the mussels and their host
fish.
Response: Although such data will be important in recovery for
these species, they are not required under the listing factors under
section 4(a) of the Act. To delay these listings until such data become
available might preclude the species from being listed until recovery
becomes less likely or extinction occurs.
Issue 17: As gravid specimens were sometimes documented, some
commenters questioned the Service's use of the term ``lack of
reproductive viability'' in the proposed rule.
Response: In the proposed rule, the Service stated that there was
little evidence to suggest that populations of the seven mussel species
were reproductively viable. This statement was based on the fact that
no known juveniles were collected during the status survey. In this
final rule, the Service has used the phrase ``lack of recruitment'' in
its discussions of mussel reproductive status. This term more
accurately defines the current status of these mussels.
Issue 18: Several commenters thought that the Service had failed to
determine potential host fish status, contending that missing hosts may
be the primary cause of their decline. Two malacologists stated that if
their fish hosts were gone, the mussels were ``functionally extinct'';
a third asked that if this were so, why spend time and effort listing
them?
Response: As discussed under ``Reproductive Biology'' in the
``Background'' section, the fish hosts for some of these species are
not currently known. Without specific host fish information, it would
be premature to spend considerable efforts and funding on fish
sampling. Population and distribution information of potential host
fish is not necessary to justify listing these species.
Loss or depletion of fish host populations may be a primary factor
in declines of some of the seven mussels. A loss of riverine habitat
has probably also affected fish populations (see Factor A in the
``Summary of Factors Affecting the Species'' section).
If some of these seven mussel species are ``functionally extinct,''
recovery may still be possible by restoration of required fish host
populations to the ecosystem. Regardless of the environmental factors
responsible for the decline of these mussels, if one or more of the
listing criteria are met, section 4 of the Act requires that the
species be listed.
Issue 19: One commenter was not convinced that mussels were
important, while numerous malacologists and other commenters stated
that mussels serve as excellent water quality indicators and barometers
of aquatic ecosystem health.
Response: Section 2(a) of the Act recognizes that species have
intrinsic values (i.e., aesthetic, ecological, educational, historical,
recreational, and scientific) to the nation, and the section 4 listing
criteria do not require other justifications. However, mussels are of
demonstrable value to man. Their longevity, relative immobility, and
filter feeding habits make them among the best available indicators of
environmental quality in aquatic systems. Mussels are highly
susceptible to sedimentation and pollutants and provide an early
warning of the deterioration of water and habitat quality. They
accumulate heavy metals and other contaminants in their tissues and
shells, serving as effective test organisms for contaminants studies.
Native Americans and early settlers fed extensively on mussels, as
shown by the large deposits of shell material in middens (Parmalee et
al. 1982). In the first half of this century, mussels supported a large
pearl button industry in the United States (McGregor and Gordon 1992).
The cultured pearl industry harvests thousands of tons of shell from
eastern rivers (Baker 1993), and cultured pearls are a multi-billion
dollar global industry. Mussels are important organisms for biological
studies, particularly because of their diverse methods of attracting
host fish.

[[Page 12674]]

Mussels serve an important ecological function by filtering excess
nutrients from the water, improving water clarity so sunlight may
promote rooted aquatic vegetation growth, thereby increasing habitat
complexity and species diversity. Several vertebrate species, including
mammals, birds, turtles, and fish feed regularly on mussels (Fuller
1974). Their shells provide substrate diversity and a place for many
types of invertebrates to colonize. This function is particularly
important in homogenous sandy coastal plain rivers where hard surfaces
are rare.
Issue 20: Two malacologists questioned the Service's statements
regarding the impacts of various human activities on the mussels,
whereas other malacologists thought that their imperilment was easily
documented given the extensive available literature. Others questioned
the use of personal communications and subjective terms (e.g., maybe,
unknown) in the proposed rule and at public meetings.
Response: Additional references documenting Service conclusions
have been added in this final rule (see ``Background'' and ``Summary of
Factors Affecting the Species'' sections). The Service believes it
appropriate to consider reliable unpublished reports, non-literature
documentation, and personal communications with experts in making
listing determinations.
Issue 21: Several commenters thought that natural factors (e.g.,
floods) and not just the factors of human origin, should be considered
in the species' imperilment.
Response: Natural factors were considered in terms of threats to
these species (see Factors C and E in the ``Summary of Factors
Affecting the Species'' section).
Issue 22: Two commenters questioned the Service's statement
concerning lack of adequate flushing on the Ochlockonee River to rid
the channel of silt and detritus below Talquin Reservoir.
Response: One survey site in the Ochlockonee River below Talquin
Reservoir had silt and detritus deposits extending from bank to bank.
Under normal conditions, these materials are confined to slackwater
areas, where they settle out in low or no-flow conditions. Low flow
releases from Talquin Reservoir may be contributing to this situation.
Issue 23: One commenter stated that these species' lack of
reservoir tolerance may be incorrect, and that it was possible that
mussels had not had enough time to reestablish themselves in the newly
created benthic habitat created by Chattahoochee River impoundments.
Response: There is no evidence that any of these seven mussels can
successfully reproduce and recruit under impoundment conditions. Their
habitat requirements generally consist of stable substrates, usually
gravel, and other rocky materials in stream channels with currents.
Habitat conditions created in impounded rivers consist of softer
sediments (i.e., silt, mud, sand) and minimal currents (except at
reservoir heads). Impoundments also change other physical and chemical
characteristics of rivers (see Factor A in the ``Summary of Factors
Affecting the Species'' section).
Issue 24: Numerous commenters maintained that the results of a
Corps-sponsored study on mussel translocation were relevant to the
proposed listings, and that the comment period should have been
extended until study results were available for public scrutiny.
Response: The Corps investigated the feasibility of translocating
four mussel species, including the purple bankclimber, in the
Apalachicola River below Jim Woodruff Dam (Hamilton et al. 1996). This
study will not provide additional information on the status of these
species and does not justify further extension of the comment period.
Issue 25: Several respondents stated that the Service cannot prove
which, if any, human activities actually affect mussels. Conversely, a
few malacologists stated that determining the direct relationship of
these impacts would be a waste of research time and taxpayer dollars.
Response: Although the precise role of the factors causing the
decline of these species will never be known, there is information
available on how human activities affect these and other species of
mussels (see ``Background'' section and Factor A in the ``Summary of
Factors Affecting the Species'' section).
Issue 26: A few malacologists questioned the rationale for
distinguishing between endangered and threatened; one of them
criticized the lack of criteria for making such distinctions. One
malacologist wondered how the Service determined that the narrowly
distributed Chipola slabshell was threatened and not endangered. They
also wondered at what point information was sufficient to list a
species.
Response: The Act defines an endangered species as a species
threatened with extinction throughout all or a significant portion of
its range, and a threatened species as a species in danger of becoming
endangered throughout all or a significant portion of its range within
the foreseeable future. The decision to propose a species as endangered
or threatened is based solely on the best scientific and commercial
data available after conducting a review of the status of the species.
For the application of these definitions to the seven mussels in
general, and the Chipola slabshell in particular, see ``Summary of
Factors Affecting the Species'' and ``Species Accounts,'' respectively.
Issue 27: One commenter stated that these seven species were
imperiled in 1970, and if the species are still extant, these listings
are long overdue.
Response: The Service believes that the status survey was essential
to determine the current status of these species before proposing them
for listing. The Service carries out status surveys and listing
actions, subject to a priority system published in the Federal Register
on September 21, 1983 (48 FR 43098), and contingent on the availability
of funding, personnel, and supportive information.
Issue 28: Several commenters thought that the Service had
overstated potential commercial utilization and take by biological
supply companies of two species, that Georgia harvest regulations
aiding in conservation had been understated, and that mussel
identification training courses were needed.
Response: Much of the commercial shell harvest in the southeast now
takes place in west Tennessee and north Alabama. Although shells from
the ACF River system are of poor quality, some have been included in
shell shipments (J. Brim Box, USGS, pers. comm.). Demand for shell in
recent years has pushed prices high enough that collectors have
searched widely for unexploited shellbeds. The fat threeridge and
purple bankclimber are so similar to the more common threeridge and
washboard (Megalonaias nervosa) that take is a potential problem.
Training and the development of educational materials will be
considered as tasks when the recovery plan is prepared for these
species.
The Service agrees that the practice of dissecting mussels in
introductory laboratory courses is no longer widespread. However, large
species, such as the fat threeridge and purple bankclimber, may still
be collected for this purpose (see factor B under ``Summary of Factors
Affecting the Species'').
Regulation of commercial harvest in Georgia has changed since the
proposed rule was drafted; this has been

[[Page 12675]]

addressed in the final rule (see Factor D in the ``Summary of Factors
Affecting the Species'' section for discussion of State regulations
affecting these species).
Issue 29: One commenter thought it was inappropriate for Service
staff to recommend that no mussels should be harvested from the ACF and
Ochlockonee River systems when some of the seven species were abundant.
Response: Although some of these species occur in large numbers at
a few sites, the Service believes the current status of the species
does not justify a harvest.
Issue 30: One commenter stated that much field data is gathered by
amateurs, and the Service should recognize the value of this
information. Two malacologists thought that we overestimated the number
of shell clubs and amateurs, and accordingly overstated their threat to
these species from collecting.
Response: The Service acknowledges the significant role amateur
malacologists have played in the development of our current knowledge
of freshwater mussels. Most early mussel collections, including most of
the type material used to describe these seven species, were collected
by amateur naturalists. Amateurs continue to make important
contributions to the knowledge of mussels. The Service agrees that the
potential threat from shell club collectors is minimal (see Factor C in
the ``Summary of Factors Affecting the Species'' section).
Issue 31: Two malacologists commented that the Service may have
taken an alarmist view with the proposal. One malacologist believed the
Service was proposing to list aquatic snails that were abundant and
unthreatened, and doubted the data used to support the listing of the
mussels.
Response: Based on the best available scientific and commercial
data and peer review, the Service believes that listing under the Act
is appropriate for these species (see ``Summary of Factors Affecting
the Species'' section).
Issue 32: A few respondents stated that the taxonomy of these
species deserved further attention as the taxonomy of some species in
the region was unresolved, and speculated that we may have been
confused regarding which species we actually proposed.
Response: Although the genetics of various mussel genera in the
Apalachicolan Region are little known (Butler 1989), the species
included in this final rule have been recognized by the malacological
community for nearly a century. All meet the Act's definition of
``species.''
Issue 33: One commenter wanted to know why one mussel species
addressed in the status survey report was omitted from the proposed
rule.
Response: The status survey included the round washboard
(Megalonaias boykiniana). In December 1993, the Service learned of
molecular genetics studies (Mulvey et al. in press) indicating that the
round washboard might be conspecific with the widespread and common
washboard. Based on this taxonomic uncertainty, this species was not
proposed for listing. The same study, however, confirmed that the fat
threeridge (Amblema neisleri) was a distinct species from the
threeridge (A. plicata).
Issue 34: One commenter suggested that mussel populations in the
relatively pristine, undisturbed Econfina Creek should be thriving
because conditions for mussels are optimal.
Response: Econfina Creek retains high water quality, but has been
altered by Deer Point Reservoir on the lower portion of the creek.
Although Gulf moccasinshell and oval pigtoe populations survive in this
stream, the populations appear to be small. Other factors may explain
why these two species occur in small numbers. Econfina Creek represents
the western-most stream within the historical range of the oval pigtoe,
and the Gulf moccasinshell's western-most extant population. Peripheral
populations in a species' range are often small and scattered.
Issue 53: One malacologist stated that Clench and Turner's (1956)
survey of Apalachicolan Region streams referred to the mussel fauna as
being depauperate, whereas the Service claimed that the region was well
known for its high level of endemicity.
Response: Clench and Turner (1956) stated ``* * * [the mussel]
fauna of [the Apalachicolan Region] has been derived from the west, is
depauperate (not rich in species), and must be fairly old.'' When
compared to adjacent drainages to the west (e.g., Mobile Basin) and
north (e.g., Tennessee River system), the fauna is relatively low in
species diversity. However, the Apalachicolan Region has many endemic
species (see ``Introduction'' in the Background section). About 30 of
the 60 mussel species known from the region are endemic (Butler 1989,
Williams and Butler 1994).
Issue 54: Two malacologists suggested that disease and predators
are not threats to these mussels, and unless information is otherwise
available, references to these factors should be deleted.
Response: Factor C (``Disease or Predation'') in the ``Summary of
Factors Affecting the Species'' section notes that there is no specific
information available on how disease and predation affect these
mussels.
Issue 55: One commenter believed that mussels were more common than
indicated in the proposed rule, because hundreds, if not thousands, of
mussels are eaten by muskrats in the vicinity of his property on the
Chattahoochee River.
Response: No populations of these seven species currently occur in
the Chattahoochee River. The mussels in question may be the Asian clam
(Corbicula fluminea), a well-known food of muskrats, or reservoir-
tolerant native mussels.
Issue 56: One commenter questioned the relationship between mussel
populations and habitat quality.
Response: Many mussels require water free from excessive levels of
sediments and contaminants (Fuller 1974, Havlik and Marking 1987). As
benthic inhabitants, they are readily affected by sedimentation, and as
filter feeders, they are highly susceptible to various contaminants
(see Factor A in the ``Summary of Factors Affecting the Species''
section).
Issue 57: Two malacologists questioned these mussels' decline when
other species in the same habitat had viable populations. Another
commenter thought the Service assumed that all seven mussels had
similar reproductive characteristics.
Response: Species occurring in the same habitat typically have
differences in life histories or ecological requirements (e.g., in the
case of mussels, different host fishes) that permit them to coexist.
These species would not be expected to respond in the same way to
ecological stress. The specific reproductive biologies of the seven
mussels is largely unknown, but would not be expected to be the same.
Issue 58: One commenter thought these mussels were always rare, and
thus served a limited ecosystem function, and further stated that the
Asian clam could fill their niche, thus minimizing a potential chain
reaction from loss of the mussels in the ecosystem.
Response: Historical information indicates that some of these
species were once locally abundant; the purple bankclimber still occurs
abundantly at a few sites. The introduced Asian clam has been common in
Apalachicolan Region rivers since 1960 (Schneider 1967) (see Factor E
in the ``Summary of

[[Page 12676]]

Factors Affecting the Species'' section). Although the Asian clam may
have become an increasingly important food for some predators (e.g.,
the muskrat), the long-term ecological consequences of its colonization
are unknown.
Issue 59: One respondent stated that data were not provided to
substantiate claims that the Asian clam may be responsible for the
imperilment of the Ochlockonee moccasinshell.
Response: Sickel (1973) and Bass and Hitt (1974) indicate that
Asian clam populations are dense in the ACF River system. This final
rule contains additional information on how Asian clams may be
impacting these seven species (see Factor E in the ``Summary of Factors
Affecting the Species'' section).
Issue 60: Several malacologists predicted that the exotic zebra
mussel (Dreissena polymorpha) will inevitably increase the probability
of extinction for the seven species based upon the impacts of this non-
native species in midwestern river systems.
Response: If the zebra mussel invades the ACF system, it may be a
serious threat to these species (see Factor E in the ``Summary of
Factors Affecting the Species'' section).
Issue 61: One commenter stated there is scientific evidence that
certain dredging, navigation, waste water discharges, silvicultural,
and agricultural activities may actually benefit filter feeders through
nutrient enrichment, flow regime modification, and temperature
modulation.
Response: The commenter provided no specific references. The
Service believes significant changes in water quality, including large
increases in sediments, decrease in flow due to impoundments, and
nutrient increases, have been generally detrimental to the native
mussel fauna (Weber 1981, Sheehan et al. 1989, Goudreau et al. 1993).
Issue 62: One commenter stated that, in certain parts of the world,
mussels were used to clean up toxic waste waters, and wondered why
these species seemed to be more susceptible to toxins when all they had
to cope with were agricultural runoff and waste water treatment plant
effluents. The individual wanted to know what chemicals were the most
toxic to mussels.
Response: Mussels are filter feeders that continually pass large
volumes of water through their bodies. Mussels take in heavy metals and
other contaminants and store them in their tissues or incorporate them
into their shells. This allows them to effectively filter pollutants
from water, but only if the species' toxicity threshold is not exceeded
or its reproductive capacity is not impaired.
Cadmium may be the most toxic heavy metal to mussels (Havlik and
Marking 1987). Other heavy metals, ammonia, and chlorine also appear to
be particularly toxic to mussels, especially in the early life stages.
Issue 63: Several respondents questioned the mussel listings if
many of their populations are non-viable. If so, not only was recovery
impossible, but the Service should not have expended funds for mussel
surveys.
Response: These mussel populations have been significantly reduced
in numbers and now exist only as fragmented populations in altered
habitats (see ``Species Accounts'' in the ``Background'' section).
Although some populations may not be viable, this does not preclude
listing. Such populations could be augmented with juveniles produced
through artificial propagation or with reproducing adults from another
population.
Issue 64: Several respondents stated that because the Service's
recovery record was poor, additional species should not be listed.
Another implied that the proposal did not contain data needed to effect
recovery or predict the species' recovery potential.
Response: A species' recovery potential is not a factor in making a
listing determination. Most endangered and threatened species reached
that status over many decades due to habitat loss and other complex
causes. Recovery of these species should not be expected to be rapid or
easy. Recovery planning and implementation occur following a species'
listing, as required by section 4(f) of the Act.
Issue 65: A few malacologists thought that it was the Service's
responsibility to see that life history studies on these species and
research on the well-being of river ecosystems should be conducted.
Response: In preparing the recovery plan for these species, the
Service will consider the need for such research and incorporate it in
the plan as appropriate.
Issue 66: Numerous commenters believed these listings would
significantly impact economies of the three States. One respondent
stated that the Service had ``juggled'' the numbers regarding section 7
consultations to mislead the public.
Response: Based on its experiences with the Act and listed mussels,
the Service does not believe the listing of these species will have a
significant effect on the economy of the three States where they occur.
A 1992 General Accounting Office audit found that 99.9 percent of all
projects (18,211) that were reviewed under the Act between 1988 and
1992 went forward unchanged or with only minor modifications. Only six
projects were halted due to endangered species considerations.
Issue 67: Numerous respondents stated that channel maintenance and
barge navigation in the ACF River system would be shut down or severely
curtailed if these species were listed.
Response: Through the section 7(a)(4) conference requirement of the
Act addressing species proposed for listing, the Service and the Corps
have agreed on measures regarding channel maintenance operations that
will avoid jeopardizing the mussel species present. These measures will
continue to be implemented once the species are listed (see ``Available
Conservation Measures'' section).
Issue 68: One respondent wanted the Service to guarantee that there
would be no financial hardship to industry, or that such costs should
be borne by the Service. Another wanted to know the if Service would
provide assurances regarding minimal potential impacts and restrictions
resulting from these listings. Several respondents requested that the
Service provide an analysis of the potential economic impacts of
listing these species.
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. The legislative history of this provision
clearly states the intent of Congress to ``ensure'' that listing
decisions are ``* * * based solely on biological criteria and to
prevent nonbiological considerations from affecting such decisions * *
*'' H.R. Rep. No. 97-835, 97th Cong., 2d Sess. 19 (1982). As further
stated in the legislative history, ``* * * economic considerations have
no relevance to determinations regarding the status of species * * *''
Id. at 20. Because the Service is specifically precluded from
considering economic impacts, either positive or negative, in a final
decision on a proposed listing, the Service need not consider the
economic impacts of listing these species.
Issue 69: The Corps disagreed with the statement that
channelization was a primary cause of habitat loss. They stated that
sediment instability in maintained channels made these areas too
unstable to maintain mussel communities.
Response: The impacts of channel modifications are addressed in
Factor A in the ``Summary of Factors Affecting the Species'' section.

[[Page 12677]]

Issue 70: The Corps stated that turbidity from dredging is not as
detrimental to benthic habitats as is runoff from streams along the
Apalachicola River after thunderstorms.
Response: Regardless of origin, impacts from sedimentation,
siltation, and turbidity sources may continue to be a problem in
portions of the ACF River system (see Factor A in the ``Summary of
Factors Affecting the Species'' section).
Issue 71: The Corps stated that the proposal did not provide
evidence for the statement that dredging activities resuspend toxicants
bound to sediments.
Response: While organochlorine insecticides were detected in less
than 10 percent of sediment and tissue samples taken in the ACF River
system during 1992 and 1993, such compounds were formerly widely used
in the basin (Buell and Couch 1995), are persistent in the environment,
toxic to aquatic life, and partitioned into both sediments and the
lipid reservoir of organisms (Day 1990, Burton 1992).
Issue 72: One respondent stated that the proposals did not explain
why impoundments were considered a primary cause of habitat loss.
Another stated that if impoundments are implicated, dams would be
required to be removed.
Response: Reservoir impacts on mussels are well documented, and
there is no evidence that any of the seven species can reproduce and
successfully recruit in impoundments (see Factor A in the ``Summary of
Factors Affecting the Species'' section). Although other factors
contributed to the mussels' decline, the Service believes reservoirs
were a significant factor. Since few if any of these species still
occur in reservoirs, dam removal is not a Service goal, nor would the
Act require such an action.
Issue 73: One commenter feared that the listings would affect ACF
River system water allocations under the Tri-State Water Study (TSW).
The Department of Energy's Southeastern Power Administration was
concerned that the mussel listings would require changes in reservoir
operations that might ultimately affect power generation capabilities.
Another individual thought the species were proposed at this time to
impact the on-going TSW study.
Response: The Service has no flow recommendations for these seven
mussels. The listing proposal was prepared after the completion of the
status survey according to normal listing priorities, and had no
connection with the TSW. However, a review of potential effects from
any proposed water allocation formula will be needed (see ``Available
Conservation Measures'' section).
Issue 74: Two malacologists stated that every human activity
affecting these species and their habitats should not have been
mentioned in the proposed rule; the Service should have focused on
specific factors (i.e., sedimentation, suspended solids, pollution)
with objective, supporting evidence.
Response: The information in the ``Summary of Factors Affecting the
Species'' section has been revised to emphasize the factors believed
most important in the decline of these mussels.
Issue 75: Some commenters disagreed with the Service's assertions
regarding the inadequacy of riparian buffers, particularly for
silvicultural activities. Another commenter stated that the Service
overlooked the fact that the State of Georgia had a law protecting
streamside buffers.
Response: The discussion of riparian buffers has been modified to
incorporate these comments (see Factor A in the ``Summary of Factors
Affecting the Species'' section).
Issue 76: Several commenters questioned the proposed rule's
implication of poor silvicultural practices as contributing to the
mussels' demise. One commenter feared there could be an impact to the
industry, whereas others requested that data be made available to
document habitat reduction as a result of these activities.
Response: Normal silvicultural activities on private lands should
not be affected by these listings (see ``Available Conservation
Measures'' section). The discussion of silvicultural activities has
been clarified in this final rule (see Factor A in the ``Summary of
Factors Affecting the Species'' section).
Issue 77: One commenter stated that timber is a long-term crop and
clear-cutting leaves land generally undisturbed for 25 years or more.
Response: Although clear-cutting may be conducted on a long-term
basis, best management practices for silvicultural activities are
important to protect stream habitats long after such activities have
occurred (see Factor A in the ``Summary of Factors Affecting the
Species'' section).
Issue 78: One respondent stated that if the mussels were listed,
subsequent recovery plans would restrict land use practices and private
property rights. Another stated that if these species are listed,
private individuals and businesses could be subject to sections 7, 9,
and 10 of the Act.
Response: Recovery plans include reasonable actions that the
Service believes necessary to bring species back to the point they no
longer need protection under the Act. They do not restrict land use
practices and private property rights. The recovery planning process is
designed to allow potentially affected segments of the public to
participate in decision making and allows the special local knowledge
of affected communities to be fully considered. Draft plans are made
available for public review and comment, and all affected or interested
individuals and groups are encouraged to participate.
Listing will provide these species the protection of sections 7
(Federal agency actions and consultations) and 9 (prohibitions) of the
Act. Section 9 ``taking'' exemptions are available under both sections
7 and 9. Section 7(b)(4) of the Act provides for incidental take
involving Federal actions if such take is not likely to jeopardize
listed species and if reasonable and prudent measures are implemented
to minimize such take. For further discussion of Federal activities
associated with these listings, see the ``Available Conservation
Measures'' section.
Section 10 of the Act provides for the issuance of permits to
conduct otherwise prohibited activities. Through section 10 habitat
conservation planning (HCP) 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, it provides long-term
assurances that their activities will be in compliance with the
requirements of the Act. Biologically, it provides the Service with a
tool to offset the incidental take of listed, proposed, candidate, and
other species by reconciling species conservation with economic
development.
Issue 79: One respondent wanted a clarification of the Service's
term ``poor land-use practices.''
Response: Poor land-use practices in the proposed rule referred to
activities that cause excessive erosion and contribute to stream
sedimentation, siltation, and turbidity. These include activities such
as clearing or plowing to the edge of stream banks, or carrying out
upland development without adequate silt screens or erosion control.
Issue 80: Several respondents stated that the species' decline
resulted from historical disturbances, and that present conditions had
improved, making listing unnecessary. Another respondent realized the
role of historical impacts,

[[Page 12678]]

but supported the listings and felt more should be done to protect the
remaining populations.
Response: Historical human activities have contributed to these
species' current status, and some factors may continue to threaten
these mussels (see Factor A in the ``Summary of Factors Affecting the
Species'' section). Although certain factors affecting these species
have improved, continuing threats to these species qualify them for
listing. Listing will provide the Act's protective and recovery
measures.
Issue 81: Several respondents thought the agricultural community
was being directly implicated in poor land use practices. Other
respondents felt better documentation was needed concerning
agricultural impacts, and believed that normal agricultural practices
would be impacted from the listings.
Response: Listing of these mussels should not affect normal
agricultural practices (see ``Available Conservation Measures''
section). Implementation of agricultural best management practices has
reduced erosion in the Apalachicolan Region, and the percentage of
agricultural lands has declined as second-growth forest has replaced
formerly cultivated lands (Couch et al. 1996). If best management
practices are followed, the Service believes that agricultural
activities will be compatible with the continued survival of these
seven mussels.
Issue 82: Several respondents stated that listing the mussels would
adversely impact the gravel-mining industry.
Response: Large-scale mining of stable substrate inhabited by these
mussels would be detrimental to them. The mining of unsuitable habitat
(i.e., unconsolidated substrates, substrates within impoundments) would
not be likely to affect them. Gravel mining in the Chattahoochee River
should be unaffected (see Factor A in the ``Summary of Factors
Affecting the Species'' section).
Issue 83: One commenter feared that these listings could cause
modification, significant construction cost increases, or even
abandonment of existing and planned waste water treatment plants.
Another commenter wanted to know what would happen to municipalities
that discharged effluents into streams inhabited by these species.
Response: The Service has no information showing that current water
quality standards threaten these species. At the time water quality
standards for particular states are reviewed under section 402 of the
Clean Water Act, the EPA will be required to consult with the Service
on any standards that may affect listed species. In the course of the
EPA review of Alabama's water quality standards, the Service's
biological opinion (dated October 8, 1996) resulting from consultation
with EPA determined that there was not sufficient information to
determine whether the standards were likely to jeopardize the continued
existence of some of the listed species found in Alabama. The opinion
anticipated incidental take for a number of listed species, required
modification of water quality standards to protect listed species, and
specified monitoring and research conditions to determine if changes in
the standards were necessary. The Service anticipates that future water
quality standard consultations will follow a similar approach.
Issue 84: The Corps recommended that a statement in the proposed
rule regarding the prolonged release of toxic chemicals from a
Department of Defense facility should be revised, and that the Service
should have considered the long-term dilution factor.
Response: A facility near Albany, Georgia, discharged an estimated
3.6 billion liters (l) (0.95 billion gallons (g)) of rinse, stripping,
cleaning, and plating solutions through a short canal into the Flint
River from 1955 to 1977. The Corps stated that the flow rate in the
Flint River provided an average dilution rate of 1:127,555 l (1:33,700
g) over the 22-year period. Many of these toxicants were heavy metals
used in plating solutions. Regardless of this dilution factor, the
Service believes the long-term release of this effluent likely had, and
may continue to have, a chronic toxic effect on Flint River mussel
populations (see Factor A in the ``Summary of Factors Affecting the
Species'' section) and deserves additional study.
Issue 85: A few commenters questioned the threat of toxic chemical
spills on highway and railway bridges over streams. Some commenters
thought that any listing would hamper efforts to rebuild bridges washed
out during major floods.
Response: Toxic chemical spills can occur at highway, railway, and
pipeline crossings, and industrial sites (see Factor A in the ``Summary
of Factors Affecting the Species'' section). Section 7 consultations
for bridge replacements are performed on a regular basis for aquatic
species throughout the southeast; occasionally, species surveys are
requested prior to construction. Most such projects do not affect, or
have minimal effects on, listed species. These listings are not
expected to affect bridge replacement.
Issue 86: One commenter wanted to know why Federal protection was
necessary if the listings would not affect individual activities.
Response: The Act requires listing based on the five criteria in
section 4(a) and does not allow for consideration of impacts, or a lack
thereof, on individual activities as part of a listing decision.
Issue 87: The Corps stated that the proposal provided minimal
evidence to prioritize human activities that may have affected mussel
habitat.
Response: Additional information on such human activities has been
provided in Factor A in the ``Summary of Factors Affecting the
Species'' section.
Issue 88: One respondent requested information relating to cost/
benefit ratios associated with recovery actions.
Response: Costs associated with implementation of recovery tasks
will be estimated when the recovery plan is developed for these
species. Cost/benefit ratios are not calculated in recovery plans.
Issue 89: One respondent asked what effect the listing would have
on commercial fishermen.
Response: The use of these mussels for bait would be a violation of
section 9 of the Act. No other effects on commercial fishermen are
anticipated.
Issue 90: Several commenters believed the Service had
misrepresented the science in the proposed rule, based upon an internal
Service memorandum. Some individuals felt the Service had changed its
position on the importance of human impacts after the proposed rule was
published.
Response: The Service believes the proposed rule was scientifically
sound, as was confirmed by peer review. Regardless of editing changes
in the draft, the proposed rule signed by the Service Director and
published in the Federal Register on August 3, 1994 (59 FR 39524),
represented the Service's position on the various threats to the seven
mussels. In formulating this final rule, the Service has considered all
substantive comments and re-examined these threats (see the ``Summary
of Factors Affecting the Species'' section).
The perception that the Service changed its position was apparently
based on the description in the proposed rule of human activities (e.g.
agriculture and forestry) that had impacted these species, versus the
Service's explanation at public meetings that the listing would have
little impact on such activities. Most of these activities are not
directly regulated or monitored by the Service or other Federal
agencies, and are, therefore, unlikely to be affected. Secondly, many
human activities result in effects that are non-point in origin (e.g.,
erosion)

[[Page 12679]]

and are not easily attributable to a particular source. The ways in
which these listings are expected to affect human activities are
discussed in the ``Available Conservation Measures'' section below.
Issue 91: EPA requested that the Service clarify the following
statement in the proposal--``Existing authorities available to protect
aquatic systems, such as the Clean Water Act [CWA] administered by EPA
and the [Corps], have not been fully utilized and may have led to the
degradation of aquatic environments in the Southeast Region, thus
resulting in a decline of aquatic species.'' EPA also requested that
the Service identify deficiencies in their implementation of the CWA
regarding State adopted narrative and numeric water quality criteria,
State water use classifications by streams occupied by these species,
aquatic life criteria guidance values; and National Pollutant Discharge
Elimination System (NPDES) permit procedures. Several respondents
questioned the need to improve regional water quality, suggesting that
existing regulations are adequate to protect the species, and that poor
water quality had been corrected since the passage of the CWA.
Response: Through implementation of the CWA, water quality has
improved following the construction of advanced waste water treatment
plants. Water quality criteria, however, were developed without
specific knowledge of the tolerances of these seven mussels and
previously listed mussels, which may be more sensitive than the species
typically used to test waste water (Keller and Zam 1991, Keller 1993).
Some mussel populations continue to decline even in areas that appear
to have suitable physical habitat. Environmental factors including
contaminants may still be adversely affecting the growth, reproduction,
recruitment, and/or survival of these populations (see Factors A and E
in the ``Summary of Factors Affecting the Species'' section). Little is
known about the potential impacts of contaminants on fresh water
mussels. Research is needed to address the lethal and sublethal effects
of acute and chronic exposure to toxins for all life stages of mussels.
This research will entail identifying appropriate surrogate species,
devising test protocols, and conducting studies to evaluate the
effectiveness of these criteria. The Service is currently working with
EPA to develop a memorandum of agreement (MOA) that will address how
EPA and the Service will interact relative to CWA water quality
criteria, standards, and NPDES permits within the Service's Southeast
Region. Until the MOA is developed and data are available to fully
evaluate the effectiveness of current national water quality standards,
the Service believes it is premature to attempt, in this final rule, to
address any specific deficiencies and/or inadequacies that may exist in
EPA's implementation of the CWA regarding the protection of water
quality.
Issue 92: One respondent questioned if the Service had complied
with the National Environmental Policy Act in the development of this
rule.
Response: See ``National Environmental Policy Act'' section.
Issue 93: A few respondents stated that current State and Federal
laws, interagency regulations, permit guidelines, and voluntary
programs governing land usage were sufficient to protect the mussels,
and thus, questioned the need to provide additional protection when
private property rights would be compromised.
Response: The Service agrees that current State and Federal laws
and regulations governing land use practices, if fully implemented,
provide significant protection for these species. However, the current
status of these seven species meets the listing criteria of the Act.
Listing will provide the additional protective and recovery provisions
of the Act.
Issue 94: Several respondents stated that listing these species
could be considered an unfunded mandate if State and local governmental
agencies are required to expend funds to satisfy permit requirements
for their protection.
Response: The Act does not mandate State participation in the
recovery of listed species, but the Service recognizes and is sensitive
to the fact that costs of some projects may increase as a result of
these listings. However, the decision to list the species is based on
biological factors regarding status and threats.
Issue 95: One respondent stated that the Service had not considered
the benefits that the erosion control practices required by the U.S.
Food Security Act have had on the aquatic environment.
Response: The Service agrees that these requirements have
benefitted mussels by reducing silt loads in streams.
Issue 96: One respondent stated that if these species are listed,
the public will not know when they are in violation of the Act until
``after the fact.''
Response: See the ``Available Conservation Measures'' section for
activities the Service believes would likely constitute violations of
section 9 of the Act.
Issue 97: One commenter stated that if the Service reintroduced
mussel populations, the public would not know where the reintroductions
occurred, or the regulatory impacts resulting from these efforts.
Response: Section 4(f)(4) of the Act requires the Service to
provide public notice and an opportunity for public review and comment
on all draft recovery plans. Establishment of an experimental
population under section 10(j) of the Act would be done by regulation,
thus, requiring the Service to identify the location of the population
and provide for a public comment period. Any population determined to
be an experimental population is treated as if it were listed as
threatened for purposes of establishing protective regulations under
section 4(d) of the Act. The special rule for the experimental
population would contain the prohibitions and exceptions for that
population.
Issue 98: Numerous commenters stated that the Service had limited
the public's opportunity to comment on the proposal by planning public
hearings outside the affected area, during the Thanksgiving holidays,
and at facilities too small to accommodate the public. They also stated
that comment periods were too short, that the Service might refuse to
pay for public hearing facilities, or had not planned to hold public
meetings.
Response: Section 4(b)(5) of the Act requires that one public
hearing be held on proposed listing regulations, if requested. Meetings
are discretionary and are held dependent on public interest and need.
In conjunction with the proposed rule, the Service held five public
information meetings followed by five public hearings in three States
throughout the range of the mussels (see first part of ``Summary of
Comments and Recommendations'' section). Meetings and hearings were
scheduled to avoid holidays or other conflicts. Meeting and hearing
sites contained seating well beyond the attendance needs at all events.
Comments were accepted at the hearings and by mail; the comment period
was opened four times, over a period of two years (59 FR 39524, 59 FR
63987, 60 FR 20072, 61 FR 36020). The Service, therefore, believes
there was adequate opportunity for public comment.
Issue 99: Several commenters stated that the Service had made the
determination to list these species prior to public consideration,
based on the term ``final rule'' having been used by Service employees
at a public meeting.
Response: The Service recognizes that during the proposal period,
the proper

[[Page 12680]]

terms relating to a regulatory decision are ``final decision'' and
``final decision document.'' This final rule has been prepared after
full consideration of all relevant comments and information received
during the comment period.
Issue 100: One respondent believed the Service had preconceived
ideas and conclusions as to the species' status prior to conducting the
status survey.
Response: The seven species were considered to be category 2
species prior to the status survey (see ``Previous Federal Action''
section), but this did not mean a decision had been made to list them.
Many species for which status surveys are carried out are found not to
meet the listing criteria of the Act.
Issue 101: Several respondents stated that the Service does not use
good science in the listing process; one respondent stated that the
listings would be arbitrary and capricious. Several respondents
believed that the Service had violated the Administrative Procedure
Act, the Act's ``best scientific and commercial data available''
standard, and Constitutional guarantees of equal protection and due
process.
Response: The Service believes that this final rule incorporates
the best available scientific and commercial information and complies
with the Administrative Procedures Act.
Issue 102: One individual stated that he was not provided an
opportunity to comment on the status survey report and the proposed
rule.
Response: The comment periods, public meetings, and public hearings
associated with the proposed rule (see ``Previous Federal Action''
section and the response to issue 98) provided extensive opportunities
for interested parties to comment on or to request copies of Service
documents.
Issue 103: One respondent commented that the Service was under
pressure to list as many as possible of the 3,000 species on the annual
notices of review.
Response: On February 28, 1996, (61 FR 7596) the Service revised
its candidate species list, replacing an old system that listed nearly
4,000 ``candidate'' species under three separate categories (see also
``Previous Federal Action'' section). The old system led many people to
the mistaken conclusion that the addition of thousands of species to
the Federal List of Endangered and Threatened Wildlife and Plants was
imminent. Under the revised list, only those species for which there is
enough information to support a listing proposal are called
``candidates.'' These were formerly known as ``category 1'' species.
The proposal to list these seven mussels followed the Service's normal
priorities and procedures.
Issue 104: Several respondents stated that the Service already
protects too many species and the country does not need any more listed
species.
Response: Section 4(a) of the Act requires species to be listed
based on the five listing factors. The Act sets no limit on the number
of species to be recognized as endangered or threatened.
Issue 105: A few commenters stated that the Service had failed to
designate critical habitat or was planning to designate critical
habitat for these species. One respondent feared that designating
critical habitat would halt navigation channel maintenance, whereas
another thought the Service should determine the critical habitat
necessary for their survival and then conduct an economic impact study.
Response: Section 4(a)(3) of the Act requires the Service to
designate critical habitat to the maximum extent prudent and
determinable at the time a species is listed. The Service has
determined that the designation of critical habitat for these seven
species is not prudent (see ``Critical Habitat'' section).
Issue 106: One commenter believed that any effort to delist a
mussel once it was placed on the Federal list would require volumes of
detailed data and be at the expense of local governments.
Response: The Act provides the same criteria to reclassify or
delist species as to list them. Subsequent to a listing, section 4(f)
of the Act requires the Service to develop and implement recovery plans
for all listed species. Recovery plans include goals for
reclassification and delisting. Section 4(c)(2) of the Act further
requires the Service to review the status of listed species every five
years to determine if reclassification or delisting is appropriate.
There is no obligation for local governments or other parties to
provide information on the status of listed species or to initiate
reclassification or delisting actions.
Issue 107: One respondent claimed the Service missed the
administrative deadline for publishing a final rule for these species.
Based on our Federal Register notice of July 9, 1996, (61 FR 36021) to
reopen the comment period, this commenter was unclear as to whether the
mussels faced ``imminent threat'' on the basis of the Service statement
that the proposals were a ``Tier 2 priority'' for listing.
Response: The congressional moratorium on final decisions on
proposed listings, from April 1995 to April 1996, precluded publication
of a final rule for these species by the Act's administrative deadline
of August 3, 1995 (see ``Previous Federal Action'' section). The
Service published listing priority guidance to address the backlog of
listing activities as a result of the moratorium (March 11, 1996 (61 FR
9651), May 16, 1996 (61 FR 24722), September 17, 1996 (61 FR 48962),
December 5, 1996 (61 FR 64475), and October 23, 1997 (62 FR 55268). The
guidance assigned the processing of a final decision for these seven
mussels to Tier 2 (resolving the listing status of outstanding proposed
rules).
The Service also solicited the expert opinions of 60 scientists
with knowledge of mussels and sampling methodologies, including most
North American malacologists. They were asked to comment on the
adequacy of the status survey in supporting the proposed rule.
Responses were received from 37 individuals and pertinent comments were
incorporated into this final rule.
Generally, the independent reviewers strongly supported the listing
proposal. Many agreed with the Service's concerns about the threats to
these species, including loss of riverine habitat, vulnerability of
specific stages of the life histories, and impaired reproduction. Seven
malacologists stated that the status survey was one of the most
comprehensive studies they were aware of.
Two malacologists suggested that the Service withdraw the proposed
rule and conduct further studies, but provided no specific information
justifying the withdrawal of the listing proposal. However, in a
written statement read at two of the public hearings, one of these
malacologists stated that ``* * * the integrity of the current study is
not questioned * * *'' (P.Yokley, Jr., University of North Alabama, in
litt. 1995).

Summary of Factors Affecting the Species

After a thorough review and consideration of all information
available, the Service has determined that the fat threeridge,
shinyrayed pocketbook, Gulf moccasinshell, Ochlockonee moccasinshell,
and oval pigtoe should be classified as endangered species, and the
Chipola slabshell and purple bankclimber should be classified as
threatened species. Procedures found at Section 4(a)(1) of the Act and
regulations implementing the listing provisions of the Act (50 CFR part
424) were followed. A species may be determined to be an endangered or
threatened species due to one

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A98-6493. Public record. Not legal advice.