Browse by Year
/ 2002
/ June
/ Thursday, June 06, 2002
[Federal Register: June 6, 2002 (Volume 67, Number 109)]
[Proposed Rules]
[Page 39105-39199]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06jn02-26]
[[Page 39105]]
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Part II
Department of the Interior
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Fish and Wildlife Service
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Department of Commerce
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National Oceanic and Atmospheric Administration
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50 CFR Parts 17 and 226
Endangered and Threatened Wildlife and Plants; Designation of Critical
Habitat for the Gulf Sturgeon; Proposed Rule
[[Page 39106]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AI23
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 226
[Docket No. 0202522126-2126-01; I.D. 052002A]
RIN 0648-AQ03
Endangered and Threatened Wildlife and Plants; Designation of
Critical Habitat for the Gulf Sturgeon
AGENCY: Fish and Wildlife Service, Interior, and National Marine
Fisheries Service, National Oceanic and Atmospheric Administration,
Commerce.
ACTION: Proposed rule.
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SUMMARY: We, the Fish and Wildlife Service (FWS) and the National
Marine Fisheries Service (NMFS), collectively ``the Services,'' propose
to designate critical habitat for the Gulf sturgeon (Acipenser
oxyrinchus desotoi), a threatened species listed under the Endangered
Species Act of 1973, as amended (Act). We propose 14 geographic areas
among the Gulf of Mexico rivers and tributaries as critical habitat for
the Gulf sturgeon. These 14 geographic areas (units) encompass
approximately 2,544 river kilometers (rkm) (1,580 river miles (rmi))
and 6,042 square kilometers (km\2\) (2,333 square miles (mi\2\)) of
estuarine and marine habitat.
Critical habitat identifies specific areas that are essential to
the conservation of a listed species, and that may require special
management considerations or protection. If this proposal is made
final, section 7(a)(2) of the Act requires that Federal agencies ensure
that actions they fund, permit, or carry out are not likely to result
in the destruction or adverse modification of critical habitat. The
regulatory effect of the critical habitat designation does not extend
beyond those activities funded, permitted, or carried out by Federal
agencies. State or private actions, with no Federal involvement, are
not affected.
Section 4 of the Act requires us to consider the economic and other
relevant impacts of specifying any particular area as critical habitat.
We hereby solicit data and comments from the public on all aspects of
this proposal, including data on the economic and other impacts of the
designation.
DATES: Comments: We will accept comments until September 23, 2002.
Public Hearings: We have scheduled four public hearings for this
proposal. We will hold public informational meetings prior to each
public hearing at the hearing location. The public information sessions
will start at 5:00 p.m. and end at 6:30 p.m.. The formal public
hearings will start at 7:00 p.m. and end at 9:00 p.m. on the dates
indicated:
(1) August 19, 2002, Live Oak, FL
(2) August 20, 2002, Defuniak Springs, FL
(3) August 21, 2002, Biloxi, MS
(4) August 22, 2002, Kenner, LA
All comments received during the comment period, both written and
presented at public hearings, will receive equal consideration.
ADDRESSES: Comments: If you wish to comment, you may submit your
comments by any one of several methods:
(1) You may submit written comments and information to the Panama
City Field Office, addressed to Patty Kelly, U.S. Fish and Wildlife
Service, 1601 Balboa Avenue, Panama City, FL 32405.
(2) You may hand-deliver written comments to the Panama City Field
Office, at the above address, or fax your comments to 850/763-2177.
(3) You may send comments by electronic mail (e-mail) to
gulfsturgeon@fws.gov. For directions on electronic filing of comments,
see the ``Public Comments Solicited'' section.
Comments and materials received, as well as supporting
documentation used in the preparation of this proposed rule, will be
available for public inspection, by appointment, during normal business
hours at the above address.
Public Hearings
(1) Suwannee River Water Management District, 9225 C.R. 49, Live
Oak, FL 32060.
(2) City of Defuniak Springs, 71 U.S. Highway 90 West, Chautauqua
Building, Museum Room, Defuniak Springs, FL 32433.
(3) J.L. Scott Marine Ed Center, 115 Beach Boulevard, Biloxi, MS
39530.
(4) Hilton New Orleans Airport, 901 Airline Drive, Kenner, LA
70062.
FOR FURTHER INFORMATION CONTACT: Patty Kelly, FWS, at the above address
(telephone 850/769-0552, extension 228; facsimile 850/763-2177) with
questions concerning units 1 to 7; or Stephania Bolden, NMFS, at 9721
Executive Center Drive North, St. Petersburg, FL 33702-2449, (telephone
727/570-5312; facsimile 727/570-5517) with questions concerning units 8
to 14.
SUPPLEMENTARY INFORMATION:
Background
The Gulf sturgeon (Acipenser oxyrinchus (=oxyrhynchus) desotoi),
also known as the Gulf of Mexico sturgeon, is an anadromous fish
(ascending rivers from the sea for breeding), inhabiting coastal rivers
from Louisiana to Florida during the warmer months and overwintering in
estuaries, bays, and the Gulf of Mexico. It is a nearly cylindrical
primitive fish embedded with bony plates or scutes. The snout is
greatly extended with four barbels in front of the mouth and the
suction type mouth is located beneath the head. The upper lobe of the
tail is longer than the lower lobe. Adults range from 1.8 to 2.4 meters
(m) (6 to 8 feet (ft)) in length, with adult females larger than males.
The Gulf sturgeon is distinguished from the geographically disjunct
Atlantic coast subspecies (A. o. oxyrinchus) by its longer head,
pectoral fins, and spleen (Vladykov 1955, Wooley 1985).
Distribution and Status
Historically, the Gulf sturgeon occurred from the Mississippi River
to Tampa Bay. Its present range extends from Lake Pontchartrain and the
Pearl River system in Louisiana and Mississippi east to the Suwannee
River in Florida. Sporadic occurrences have been recorded as far west
as the Rio Grande River between Texas and Mexico, and as far east and
south as Florida Bay (Wooley and Crateau 1985, Reynolds 1993).
In the late 19th century and early 20th century, the Gulf sturgeon
supported an important commercial fishery, providing eggs for caviar,
flesh for smoked fish, and swim bladders for isinglass, a gelatin used
in food products and glues (Carr 1983). Gulf sturgeon numbers declined
due to overfishing throughout most of the 20th century. The decline was
exacerbated by habitat loss associated with the construction of water
control structures, such as dams and sills, mostly after 1950. In
several rivers throughout its range, dams have severely restricted
sturgeon access to historic migration routes and spawning areas
(Boschung 1976, Wooley and Crateau 1985, McDowell 1988).
On September 30, 1991, we listed the Gulf sturgeon as a threatened
species under the Act (16 U.S.C. 1531 et seq.) (56 FR 49653). Other
threats and potential threats identified in the listing
[[Page 39107]]
rule included modifications to habitat associated with dredged material
disposal, de-snagging, and other navigation maintenance activities;
incidental take by commercial fishermen; poor water quality associated
with contamination by pesticides, heavy metals, and industrial
contaminants; aquaculture and incidental or accidental introductions;
and the Gulf sturgeon's slow growth and late maturation. The Gulf
sturgeon listing rule and the Gulf Sturgeon Recovery/Management Plan
(FWS et al. 1995), which was approved by the Services and the Gulf
States Marine Fisheries Commission, provide a more detailed discussion
of the reasons for the species' decline and threats to surviving
populations.
The Gulf Sturgeon Recovery/Management Plan (FWS et al. 1995)
recommended that genetic studies be done to determine geographically
distinct management units. Some work in this regard has been completed
(Waldman and Wirgin 1998), but we have not formally adopted management
units at this time. For purposes of this proposed rule, we have used
the term subpopulation to subdivide the Gulf sturgeon population based
on geography, degree of connectedness, and genetic interchange (Lande
and Barrowclough 1987). Seven subpopulations are described below.
Feeding Habits
Gulf sturgeon feeding habits in freshwater vary depending on the
fish's life history stage (i.e., young-of-year, juvenile, subadult,
adult). Young-of-year Gulf sturgeon remain in freshwater through early
February feeding on aquatic invertebrates and detritus (Mason and
Clugston 1993, Sulak and Clugston 1999). Juvenile feeding is believed
to be widely distributed, exploiting scarce food resources throughout
the river, including aquatic insects (e.g., mayflies and caddisflies),
worms (oligochaetes), and bivalve molluscs (Huff 1975, Mason and
Clugston 1993). Mason and Clugston (1993) found that subadult and adult
Gulf sturgeon collected during June and October do not feed in fresh
water.
Many reports indicate that adult and subadult Gulf sturgeon fast
and lose up to 30 percent of their total body weight while in fresh
water, and then compensate the loss during winter feeding in the sea
(Carr 1983, Wooley and Crateau 1985, Clugston et al. 1995, Morrow et
al. 1998a, Heise et al. 1999a, Sulak and Clugston 1999, Ross et al.
2000). Gu et al. (2001) tested the hypothesis that Gulf sturgeon do not
feed significantly during their annual residence in fresh waters by
comparing stable carbon isotope ratios of tissue samples from subadult
and adult Suwannee River Gulf sturgeon and their potential fresh water
and marine food sources. A large difference in isotope ratios between
fresh water food sources and fish muscle tissue suggests that Gulf
sturgeon do not feed significantly in fresh waters. The isotope
similarity between Gulf sturgeon and marine food resources strongly
indicates that this species relies almost entirely on the marine food
web for its growth (Gu et al. 2001).
Once Gulf sturgeon leave the river, having spent at least 6 months
in the river fasting, we presume that they immediately begin feeding.
Upon exiting the rivers, Gulf sturgeon are found in high concentrations
near their natal river mouths. Lakes and bays at the mouths of the
river systems where Gulf sturgeon occur are important because they
offer the first opportunity for Gulf sturgeon exiting their natal
rivers to forage. Gulf sturgeon rely almost entirely on estuarine and
marine food for their growth (Gu et al. 2001). Gulf sturgeon must be
able to consume sufficient quantities of prey while in estuarine and
marine waters to regain the weight they lose while in the river system
and to maintain positive growth on a yearly basis. In addition,
reproductive Gulf sturgeon require additional food resources to obtain
sufficient energy necessary for reproduction (Fox et al. in press,
Murie and Parkyn pers. comm. 2002).
Adult and subadult Gulf sturgeon, during marine and estuarine
periods, are thought to forage opportunistically (Huff 1975), primarily
on benthic (bottom dwelling) invertebrates. Gut content analyses have
indicated that the Gulf sturgeon's diet is predominated by amphipods,
lancelets, polychaetes, gastropods, shrimp, isopods, molluscs, and
crustaceans (Huff 1975, Mason and Clugston 1993, Carr et al. 1996b, Fox
et al. 2000, Fox et al. in press). Gulf sturgeon from the Suwannee
River subpopulation are known to forage on brachiopods (D. Murie and D.
Parkyn, University of Florida (UF), pers. comm. 2002); however this is
not a documented prey of other subpopulations. Ghost shrimp
(Lepidophthalmus louisianensis) and the haustoriid amphipod
(Lepidactylus sp.) are strongly suspected to be the most important prey
for adult Gulf sturgeon over 20 kilograms (kg) (44 pounds (lb)) (Heard
et al. 2000, Fox et al. in press). This hypothesis is based on the
following evidence--(1) Gulf sturgeon have been consistently located
and observed actively feeding in areas where numerous burrows similar
to those occupied by ghost shrimp exist (Fox et al. 2000) and with high
densities of both ghost shrimp and haustoriid amphipods (Heard et al.
2000), (2) the digestive tracts of two adult Gulf sturgeon that died
during netting operations contained numerous ghost shrimp (Fox et al.
2000), (3) stomach contents of a 30 kg (67 lb) sturgeon taken in the
upper portion of Choctawhatchee Bay contained more than 100 individual
haustoriid amphipods and 67 ghost shrimp (Heard et al. 2000), and (4)
one-third of 157 sturgeon guts analyzed by Carr et al. (1996b)
contained exclusively brachipods and ghost shrimp.
Reproduction
Gulf sturgeon are long-lived, with some individuals reaching at
least 42 years in age (Huff 1975). Age at sexual maturity for females
ranges from 8 to 17 years, and for males from 7 to 21 years (Huff
1975). Gulf sturgeon eggs are demersal (they are heavy and sink to the
bottom), adhesive, and vary in color from gray to brown to black
(Vladykov 1963, Huff 1975, Parauka et al. 1991). Chapman et al. (1993)
estimated that mature female Gulf sturgeon produce an average of
400,000 eggs. Habitat at egg collection sites consist of limestone
bluffs and outcroppings, cobble, limestone bedrock covered with gravel
and small cobble, gravel, and sand (Marchant and Shutters 1996, Sulak
and Clugston 1999, Fox et al. 2000). A dense matrix of gravel or cobble
is probably essential for Gulf sturgeon egg adhesion and the sheltering
of the yolk sac larvae, and is a habitat the adults apparently select
(Sulak and Clugston 1999). Other substrates identified as possible
spawning habitat include marl (clay with substantial calcium
carbonate), soapstone, or hard clay (W. Slack, Mississippi Museum of
Natural Science, pers. comm. 2002; F. Parauka, FWS, pers. comm. 2002).
Water depths at egg collection sites ranged from 1.4 to 7.9 m (4.6 to
26 ft), with temperatures ranging from 18.3 to 22.0 degrees Celsius
( deg.C) (64.9 to 71.6 degrees Fahrenheit ( deg.F)) (Fox et al. 2000).
Laboratory experiments indicated optimal water temperature for survival
of Gulf sturgeon larvae is between 15 and 20 deg.C (59 and 68 deg.F),
with low tolerance to temperatures above 25 deg.C (77 deg.F) (Chapman
and Carr 1995).
Sulak and Clugston (1999) suggested that sturgeon spawning activity
in the Suwannee River is related to the lunar phase of the moon, but
only after the water temperature has risen to 17 deg.C (62.6 deg.F).
Fox et al. (in press) however, found little evidence of spawning
associated with lunar cycles within the Choctawhatchee River system.
[[Page 39108]]
Spawning in the Suwannee River occurs during the general period of
spring high water, when ionic conductivity and calcium ion
concentration are most favorable for egg development and adhesion
(Sulak and Clugston 1999). Fox et al. (in press) found no clear pattern
between timing of river entrance and flow patterns on the
Choctawhatchee River.
Atlantic sturgeon (A. oxyrhynchus) exhibit a long inter-spawning
period, with females spawning at intervals ranging from every 3 to 5
years, and males every 1 to 5 years (Smith 1985). It is believed that
Gulf sturgeon exhibit similar behavior, as male Gulf sturgeon are
capable of annual spawning, and females require more than one year
between spawning events (Huff 1975, Fox et al. 2000).
Fresh Water Habitat
In the spring (March to May), adult and subadult Gulf sturgeon
return to their natal river, where sexually mature sturgeon spawn, and
the population spends until October or November (6 to 8 months) in
fresh water rivers (Odenkirk 1989, Foster 1993, Clugston et al. 1995,
Fox et al. 2000). During their early life history stages, sturgeon
require bedrock and clean gravel or cobble substrate for eggs to adhere
to and for shelter for developing larvae (Sulak and Clugston 1998).
Young-of-year appear to disperse widely, using extensive portions of
the river as nursery habitat. They are typically found on sandbars and
sand shoals over rippled bottom and in shallow, relatively open,
unstructured areas. This dispersion may be an adaptation to maximize
scarce food resources (Randall and Sulak 1999). Clugston et al. (1995)
reported that young Gulf sturgeon in the Suwannee River, weighing
between 0.3 and 2.4 kg (0.7 and 5.3 lb), remain in the vicinity of the
river mouth and estuary during the winter and spring.
Adult Gulf sturgeon spawn in upper river reaches. On some river
systems such as the Pascagoula River and Apalachicola River, adult and
subadult Gulf sturgeon remain near the spawning grounds throughout the
summer months (Wooley and Crateau 1985, Ross et al. 2001b). However, in
other rivers Gulf sturgeon spawn and move downstream to areas referred
to as summer resting or holding areas. Adults and subadults are not
distributed uniformly throughout the river, but show a preference for
these discrete areas usually located in lower and middle river reaches
(Potak et al. 1995). Often, these resting areas are located in close
proximity to springs throughout the warmest months of the year, but not
located within a spring or thermal plume emanating from a spring
(Clugston et al. 1995, Potak et al. 1995, Foster and Clugston 1997).
These resting areas are also often located in deep holes or shallow
areas along straight-aways ranging from 2 to 19 m (6.6 to 62.3 ft) deep
(Wooley and Crateau 1985, Morrow et al. 1998a, Ross et al. 2001a and b,
Craft et al. 2001, Hightower et al. in press). The substrates consisted
of mixtures of limerock and sand (Clugston et al. 1995), sand and
gravel (Wooley and Crateau 1985, Morrow et al. 1998a), or just sandy
substrate (Hightower et al. in press).
River flow may serve as an environmental cue that governs both
sturgeon migration and spawning (Chapman and Carr 1995). If the flow
rate is too high, sturgeon in several life-history stages can be
adversely affected. Data describing the sturgeon's swimming ability in
the Suwannee River strongly indicated that they cannot continually swim
against prevailing currents of greater than 1 to 2 m per second (3.2 to
6.6 ft per second) (Wakeford 2001). If the flow is too strong, eggs
might not be able to settle on and adhere to suitable substrate
(Wakeford 2001). Flow velocity needs for age zero sturgeon may vary
depending on substrate type. Chan et al. (1997) found that age zero
Gulf sturgeon under laboratory conditions exposed to water velocities
over 12 centimeters per second (cm/s) (4.7 inches per second (in/s))
preferred a cobble substrate, but favored water velocities under 12 cm/
s (4.7 in/s) and then utilized a variety of substrates (sand, gravel,
and cobble). Natural surface and groundwater discharges influence a
river's characteristic fluctuations in volume, depth, and velocity
(Leitman et al. 1993, Albertson and Torak 2002).
Gulf sturgeon require large areas of diverse habitat that have
natural variations in water flow, velocity, temperature, and turbidity
(FWS et al. 1995, Wakeford 2001). Change in temperature is one of the
most important factors in initiating sturgeon migration (Wooley and
Crateau 1985, Chapman and Carr 1995, Foster and Clugston 1997) (see the
``Migration'' section for temperature ranges). Laboratory experiments
show that Gulf sturgeon eggs, embryos, and larvae have the highest
survival rates when temperatures are between 15 and 20 deg.C (59 and
68 deg.F). Mortality rates of Gulf sturgeon gametes and embryos are
highest when temperatures are 25 deg.C (77 deg.F) and above (Chapman
and Carr 1995) (see ``Reproduction'' section for more detail).
Researchers have documented temperature ranges at Gulf sturgeon resting
areas between 15.3 and 33.7 deg.C (59.5 and 92.7 deg.F) with dissolved
oxygen levels between 5.6 and 9.1 milligrams per liter (mg/l) (Morrow
et al. 1998a, Hightower et al. in press).
In comparison to other fish species, sturgeon have a limited
behavioral and physiological capacity to respond to hypoxia
(insufficient oxygen levels) (Secor and Niklitschek 2001). Basal
metabolism, growth, consumption, and survival are sensitive to changes
in oxygen levels (Secor and Niklitschek 2001). Temperatures greater
than 20 deg.C (68 deg.F) amplify the effect of hypoxia on sturgeon and
other fishes (Coutant 1987). In laboratory experiments, young shortnose
sturgeon (A. brevirostrum) (less than 77 days old) died at oxygen
levels of 3.0 mg/l and all sturgeon died at oxygen levels of 2.0 mg/l
(Jenkins et al. 1993). Data concerning the temperature, oxygen, and
current velocity requirements of cultured sturgeon are being collected.
Researchers plan to use this information to develop detailed
information on water flow requirements of wild sturgeon throughout
different phases of their fresh water residence (Wakeford 2001).
Estuarine and Marine Habitat
Subadult and adult Gulf sturgeon spend cool months (October or
November through March or April) in estuarine areas, bays, or in the
Gulf of Mexico (Odenkirk 1989, Foster 1993, Clugston et al. 1995).
Studies of subadult Gulf sturgeon (ages 4 to 7) in Choctawhatchee Bay
found that 78 percent of tagged fish remained in the bay the entire
winter, while 13 percent ventured into a connecting bay. Possibly 9
percent spent some time in the Gulf of Mexico (FWS 1998). Adult Gulf
sturgeon are more likely to overwinter in the Gulf of Mexico, with 40
percent of the tagged adults presumed to have left Choctawhatchee Bay
and spent extended periods of time in the Gulf of Mexico (Fox and
Hightower 1998a). In contrast, Gulf sturgeon from the Suwannee River
subpopulation are known to migrate into the nearshore waters, where
they remain for up to two months and then depart to unknown feeding
locations in the open Gulf of Mexico (Carr et al. 1996b, Edwards et al.
in prep.).
Subadult Gulf sturgeon show a preference for sandy shoreline
habitats with water depths less than 3.5 m (11.5 ft) and salinities
less than 6.3 parts per thousand (Parauka et al. in press). Fox and
Hightower (1998a) found that adult Gulf sturgeon monitored in
Choctawhatchee Bay use some of the same habitats as subadults. Some
subadult Gulf sturgeon use seagrass
[[Page 39109]]
habitats in Choctawhatchee Bay. However, the majority of tagged fish
have been located in areas lacking seagrass (Parauka et al. in press).
Adult Gulf sturgeon also have not been frequently found in areas
containing seagrass, which were concentrated in the western portion of
the bay.
Craft et al. (2001) found that Gulf sturgeon in Pensacola Bay
appear to prefer shallow shoals 1.5 to 2.1 m (5 to 7 ft) and deep holes
near passes. Unvegetated, fine to medium-grain sand habitats, such as
sandbars, and intertidal and subtidal energy zones resulting in
sediment sorting and a preponderance of sand support a variety of
potential prey items including estuarine crustaceans, small bivalve
mollusks, and lancelets (Brim pers. comm. 2002, Menzel 1971, Abele
1986, American Fisheries Society 1989).
Habitats used by Gulf sturgeon in the vicinity of the Mississippi
Sound barrier islands tend to have a sand substrate and an average
depth of 1.9 to 5.9 m (6.2 to 19.4 ft). Preliminary data from bottom
samples taken in these barrier island areas show that all samples
contain lancelets (Branchiostoma). Since lancelets are a documented
prey of Gulf sturgeon, it is likely that Gulf sturgeon are feeding
along the sand substrate at barrier island passes (Ross et al. 2001a).
Gulf nearshore (less than 1.6 km (1 mi)) unconsolidated, fine-medium
grain sands, including natural inlets and passes from the Gulf to
estuaries, support crustaceans such as mole crabs, sand fleas, various
amphipod species, and lancelets (Brim pers. comm. 2002, Menzel 1971,
Abele 1986, American Fisheries Society 1989).
Estuary and bay unvegetated ``mud'' habitats having a preponderance
of natural silts and clays support burrowing and deep burrowing
crustaceans, such as ghost shrimp, small crabs, also various polychaete
worms, and small bivalve mollusks (Brim pers. comm. 2002, Menzel 1971,
Abele 1986, American Fisheries Society 1989). Gulf sturgeon are found
in these areas and since these are known food sources, it is assumed
that Gulf sturgeon are also feeding in these areas.
Migration
Migratory behavior of the Gulf sturgeon varies by sex, maturity,
water temperature, and river flow. Male Gulf sturgeon generally enter
the rivers earlier in the spring and move greater distances than
females; ripe (in reproductive condition) males and females enter the
river earlier than nonripe fish (Fox et al. 2000). Adults and subadults
begin moving from the estuaries, bays, and Gulf of Mexico into the
coastal rivers in early spring (i.e., March through May) when river
water temperatures range from 16.0 to 23. deg.C (60.8 to 73.4 deg.C)
(Huff 1975, Carr 1983, Wooley and Crateau 1985, Odenkirk 1989, Clugston
et al. 1995, Foster and Clugston 1997, Fox and Hightower 1998, Sulak
and Clugston 1999, Fox et al. 2000). Some research supports the theory
that spring migration coincides with the general period of spring high
water (Sulak and Clugston 1999), while observations on other rivers
systems do not support this theory (Fox et al. in press).
Fall downstream migration from fresh to saltwater begins in
September (at about 23 deg.C (73.4 deg.F)) and continues through
November (Huff 1975, Wooley and Crateau 1985, Foster and Clugston
1997). During the fall migration from fresh to saltwater, Gulf sturgeon
may require a period of physiological acclimation to changing salinity
levels, referred to as osmoregulation or staging (Wooley and Crateau
1985). This period may be short (Fox et al. in press) as sturgeon
develop an active mechanism for osmoregulation and ionic balance by age
one (Altinok 1997). On some river systems, timing of the fall migration
appears to be associated with pulses of higher river discharge (Heise
et al. 1999a and b, Ross et al. 2000 and 2001b, Parauka et al. in
press).
Sturgeon ages 1 through 6 remain in the mouth of the Suwannee River
over winter. In late January through early February, young-of-the-year
Gulf sturgeon migrate down river for the first time (Sulak and Clugston
1999). Huff (1975) noted that juvenile Gulf sturgeon in the Suwannee
River most likely participated in pre- and post-spawning migrations,
along with the adults.
Findeis (1997) describes sturgeon (Acipenseridae) as exhibiting
evolutionary traits adapted for benthic cruising. Tracking observations
by Sulak and Clugston (1999), Edwards et al. (in prep.), and Fox et al.
(in press) support that individual fish move over an area until they
encounter suitable prey type and density, at which time they forage for
extended periods of time. Individual fish often remained in localized
areas (less than 1 km\2\ (0.4 mi\2\) for extended periods of time
(greater than two weeks) and then moved rapidly to another area where
localized movements occurred again (Fox et al. in press). It is unknown
precisely how much benthic area is needed to sustain Gulf sturgeon
health and growth, but because Gulf sturgeon have been known to travel
long distances (greater than 161 km (100 mi)) during their winter
feeding phase, significant resources must be necessary. These winter
migrations are an important strategy for feeding and for occasional
travel to non-natal rivers for possible spawning and genetic
interchange. Bays and portions of Gulf of Mexico waters adjacent to the
lakes and bays near the mouths of the rivers where Gulf sturgeon occur
are believed to be important for feeding and/or migrating (for
increased gene flow and, therefore, increased genetic stability among
subpopulations).
When temperature drops occur that are associated with major cold
fronts, researchers of the Escambia, Yellow, and Suwannee River
subpopulations have been unable to locate adult Gulf sturgeon within
the bays (Craft et al. 2001, Fox et al. in press, Edwards et al. in
prep.). It is hypothesized that the cold fronts disperse sturgeon to
more distant foraging grounds. It is currently unknown whether Gulf
sturgeon undertake extensive offshore migrations, and further study is
needed to determine whether important winter feeding habitat occurs in
farther offshore areas.
Sulak and Clugston (1999) describe two hypotheses regarding where
adult Gulf sturgeon may overwinter in the Gulf of Mexico to find
abundant prey. The first hypothesis is that Gulf sturgeon spread along
the coast in nearshore waters in depths less than 10 m (33 ft). The
alternative hypothesis is that they migrate far offshore to the broad
sedimentary plateau in deep water (40 to 100 m (131 to 328 ft)) west of
the Florida Middle Grounds, where over twenty species of bottom-feeding
fish congregate in the winter (Darnell and Kleypas 1987). Available
data support the first hypothesis. Evaluation of tagging data has
identified several nearshore Gulf of Mexico feeding migrations, but no
offshore Gulf of Mexico feeding migrations. Telemetry data document
Gulf sturgeon from the Pearl River and Pascagoula River subpopulations
migrate from their natal bay systems to Mississippi Sound and move
along the barrier islands on both the barrier island passes (Ross et
al. 2001a, Rogillio et al. in prep.). Gulf sturgeon from the
Choctawhatchee River, Yellow River, and Apalachicola River have been
documented migrating in the nearshore Gulf of Mexico waters between
Pensacola and Apalachicola Bays units (Fox et al. in press, F. Paruka
pers. comm. 2002). Telemetry data from the Gulf of Mexico mainly show
sturgeon in depths of 6 m (19.8 ft) or less (Ross et al. 2001a,
Rogillio et al. in prep., Fox et al. in press, F. Paruka pers. comm.
2002).
[[Page 39110]]
River-Specific Fidelity
Stabile et al. (1996) analyzed Gulf sturgeon subpopulations from
eight drainages along the Gulf of Mexico for genetic diversity. They
noted significant differences among Gulf sturgeon stocks and suggested
that they displayed region-specific affinities and may exhibit river-
specific fidelity. Stabile et al. (1996) identified five regional or
river-specific stocks (from west to east)--(1) Lake Pontchartrain and
Pearl River, (2) Pascagoula River, (3) Escambia and Yellow Rivers, (4)
Choctawhatchee River, and (5) Apalachicola, Ochlockonee, and Suwannee
Rivers.
Tagging studies suggest that Gulf sturgeon exhibit a high degree of
river fidelity. From 1981 to 1993, 4,100 fish were tagged in the
Apalachicola and Suwannee Rivers. Of these, 860 fish (21 percent) were
recaptured in the river of their initial collection. Only eight
subadults (.002 percent) moved between rivers (FWS et al. 1995). Foster
and Clugston (1997) noted that telemetered Gulf sturgeon in the
Suwannee River returned to the same areas as the previous summer,
suggesting that chemical cuing may influence distribution.
To date, biologists have documented a total of 21 Gulf sturgeon
making inter-river movements from natal rivers. They are as follows--
Apalachicola River to Suwannee River, six Gulf sturgeon (Carr et al.
1996b); Suwannee River to Apalachicola River, three sturgeon (Carr et
al. 1996b, F. Parauka pers. comm. 2002); Choctawhatchee River to
Apalachicola River, one sturgeon (F. Parauka pers. comm. 2002); Yellow
River to Choctawhatchee River, three sturgeon (one adult female, one
subadult female) (Craft et al. 2001); Yellow River to Louisiana
Estuarine area, one female sturgeon (Craft et al. 2001); Escambia River
to Yellow River, one mature female on spawning grounds (Craft et al.
2001); Suwannee River to Ochlockonee River, one sturgeon (FWS et al.
1995); Choctawhatchee River to Escambia River, one male sturgeon (Fox
et al. in press); Choctawhatchee River to Escambia, one female sturgeon
(Fox et al. in press); Pearl River (Bogue Chitto) to Pascagoula River,
one sturgeon (Ross et al. 2001b); Choctawhatchee River to Pascagoula
River, one subadult sturgeon (Ross et al. 2001b); and Pascagoula River
to Yellow River, one sturgeon (Ross et al. 2001b). Tallman and Healey
(1994) note that observed straying rates between rivers were not the
same as actual gene flow rates, i.e. inter-stock movement does not
equate to successful reproduction. The gene flow is low in Gulf
sturgeon stocks, with each stock exchanging less than one mature female
per generation (Waldman and Wirgin 1997).
Previous Federal Action
Federal action on the Gulf sturgeon began in 1982, when the fish
was included as a Category 2 candidate species for listing in the FWS's
vertebrate notices of review dated December 30, 1982 (47 FR 58454) and
September 18, 1985 (50 FR 37958), and in the animal notice of review
dated January 6, 1989 (54 FR 554). At that time, the FWS gave Category
2 designation to species for which listing as threatened or endangered
was possibly appropriate, but for which additional biological
information was needed to support a proposed rule. A status report on
the Gulf sturgeon (Hollowell 1980) had concluded that the fish had been
reduced to a small population due to overfishing and habitat loss. In
1988, the FWS completed a report on the conservation status of the Gulf
sturgeon, which recommended listing it as a threatened species
(Barkuloo 1988).
The Services jointly proposed the Gulf sturgeon for listing as a
threatened species on May 2, 1990 (55 FR 18357). In that proposed rule,
we stated that designation of critical habitat was not prudent due to
the species' broad range and the lack of knowledge about specific areas
used by the species. We published the final rule on September 30, 1991
(56 FR 49653) to add Gulf sturgeon to the list of threatened species,
and included a special rule under section 4(d) of the Act to allow the
take of Gulf sturgeon, in accordance with applicable State fish and
wildlife conservation laws and regulations, for educational and
scientific purposes, the enhancement of propagation or survival of the
species, zoological exhibition, and other conservation purposes. In the
final rule, we found that a critical habitat designation may be prudent
but was not determinable. Section 4(b)(6)(C) of the Act provides that a
concurrent critical habitat determination is not required with a final
regulation implementing endangered or threatened status and that the
final designation may be postponed for one additional year beyond the
period specified in section 4(b)(6)(A), if a prompt determination of
endangered or threatened status is essential to the conservation of the
species, or critical habitat is not then determinable. We found that
prompt determination of threatened status was essential to the
conservation of the species and stated that we would make a final
decision on designation of critical habitat by May 2, 1992. This
decision, however, was not made.
On August 11, 1994, the Sierra Club Legal Defense Fund, Inc.
(Fund), on behalf of the Orleans Audubon Society and Florida Wildlife
Federation, gave written notice of their intent to file suit against
the Department of the Interior for failure to designate critical
habitat for the Gulf sturgeon within the statutory time limits
established under the Act. The Fund filed suit on October 11, 1994
(Orleans Audubon Society v. Babbitt, Civ. No. 94-3510 (E.D. La)).
Following a court order on August 9, 1995, granting the Fund's motion
for summary judgement, the Services published a notice of decision on
critical habitat designation for the Gulf sturgeon on August 23, 1995
(60 FR 43721). We determined that critical habitat designation was not
prudent based on the lack of additional conservation benefit to the
species.
On September 22, 1995, the Services and the Gulf States Marine
Fisheries Commission approved the Gulf Sturgeon Recovery/Management
Plan (FWS et al. 1995). The recovery plan established the criteria that
must be met prior to the delisting of the Gulf sturgeon. The recovery
plan also identified the actions that are needed to assist in the
recovery of the Gulf sturgeon.
On August 12, 1996, the plaintiffs filed a motion to add the
Department of Commerce as a defendant in the lawsuit. The Fund amended
their complaint to challenge the August 1995 ``not prudent''
determination. On October 30, 1997, the court granted the plaintiffs'
motion for summary judgment, with relief restricted to a remand of the
``not prudent'' determination to the Services, requiring that the
Services publish a determination on designation of critical habitat,
based on the best scientific information available. On February 27,
1998, we published a notice of decision (63 FR 9967) on critical
habitat designation for the Gulf sturgeon. We again determined that
lack of additional conservation benefit from critical habitat
designation for this species made such designation not prudent.
On December 18, 1998, the Sierra Club sued the Services challenging
the new determination not to designate critical habitat for the Gulf
sturgeon (Sierra Club v. U.S. Fish and Wildlife Service et al. CA No.
98-3788 (E.D. La.)). On January 25, 2000, the Court issued an order
granting our motion for summary judgment and dismissing the complaint.
The Sierra Club filed an appeal and, in March 2001, the United States
Court of Appeals for the Fifth Circuit reversed the decision of the
[[Page 39111]]
District Court and instructed the District Court to remand the decision
to us for reconsideration (Sierra Club v. U.S. Fish and Wildlife
Service, 245 F.3d 434 (5th Cir. 2001)). On August 3, 2001, the District
Court issued an order directing us to publish a proposed decision
concerning critical habitat designation for the Gulf sturgeon by
February 2, 2002, and a final decision by August 2, 2002. Negotiation
with the plaintiff resulted in an agreement to publish the proposed
decision by May 23, 2002, and the final decision by February 28, 2003.
This proposal is the product of our reexamination of our 1998
prudency determination for the Gulf sturgeon. It reflects our
interpretation of the recent judicial opinions on critical habitat
designation and the standards placed on us for making a prudency
determination. If additional information becomes available on the
species' biology and distribution and threats to the species, we may
reevaluate this proposal to designate critical habitat, including
proposing additional critical habitat, proposing the deletion or
boundary refinement of existing proposed critical habitat, or
withdrawing our proposal to designate critical habitat.
Critical Habitat
Critical habitat is defined in section 3(5)(A) of the Act as (i)
the specific areas within the geographic area occupied by a species, at
the time it is listed in accordance with the Act, on which are found
those physical or biological features (I) essential to the conservation
of the species and (II) that may require special management
considerations or protection; and (ii) specific areas outside the
geographic area occupied by a species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species. ``Conservation'' is defined in section 3(3) of the Act as the
use of all methods and procedures that are necessary to bring any
endangered or threatened species to the point at which listing under
the Act is no longer necessary.
In order for habitat to be included in a critical habitat
designation, the habitat features must be ``essential to the
conservation of the species.'' Such critical habitat designations
identify, to the extent known using the best scientific data available,
habitat areas that provide essential life cycle needs of the species
(i.e., areas on which are found the primary constituent elements, as
defined at 50 CFR 424.12(b)).
Regulations at 50 CFR 424.02(j) define special management
considerations or protection to mean any methods or procedures useful
in protecting the physical and biological features of the environment
for the conservation of listed species. If any areas containing the
primary constituent elements are currently being managed to address the
conservation needs of the Gulf sturgeon, they may not require special
management or protection, and, therefore, may not meet the definition
of critical habitat in section 3(5)(A)(i) of the Act.
When we designate critical habitat, we may not have the information
necessary to identify all areas which are essential for the
conservation of the species. Nevertheless, we are required to designate
those areas we know to be critical habitat, using the best information
available to us.
Within the geographic area of the species, we will designate only
currently known essential areas. We will not speculate about what areas
might be found to be essential if better information became available,
or what areas may become essential over time. If the information
available at the time of designation does not show that an area
provides essential life cycle needs of the species, then the area will
not be included in the critical habitat designation. Our regulations
state that, ``The Secretary shall designate as critical habitat areas
outside the geographic area presently occupied by the species only when
a designation limited to its present range would be inadequate to
ensure the conservation of the species'' (50 CFR 424.12(e)).
Accordingly, when the best available scientific data do not demonstrate
that the conservation needs of the species require designation of
critical habitat outside of occupied areas, we will not designate
critical habitat in areas outside the geographic area occupied by the
species.
Section 4(b)(2) of the Act requires that we take into consideration
the economic impact, and any other relevant impact, of specifying any
particular area as critical habitat. We may exclude areas from critical
habitat designation when the benefits of exclusion outweigh the
benefits of including the areas within critical habitat, provided the
exclusion will not result in extinction of the species.
Our Policy on Information Standards Under the Endangered Species
Act, published on July 1, 1994 (59 FR 34271), provides guidance to
ensure that our decisions are based on the best scientific and
commercial data available. It requires that our biologists, to the
extent consistent with the Act and with the use of the best scientific
and commercial data available, use primary and original sources of
information as the basis for recommendations to designate critical
habitat. When determining which areas are critical habitat, information
that should be considered includes the listing package for the species,
the recovery plan, articles in peer-reviewed journals, conservation
plans developed by States and Counties, scientific status surveys,
studies, and biological assessments, unpublished materials, and expert
opinion or personal knowledge.
Habitat is often dynamic, however, and populations may move from
one area to another over time. Furthermore, we recognize that
designation of critical habitat may not include all of the habitat
areas that may eventually be determined to be necessary for the
recovery of the species. Therefore, critical habitat designations do
not signal that habitat outside the designation is unimportant or may
not be required for recovery. Areas outside the critical habitat
designation will continue to be subject to conservation actions that
may be implemented under section 7(a)(1) of the Act and to the
regulatory protections afforded by the section 7(a)(2) jeopardy
standard and the section 9 of the Act take prohibition, as determined
on the basis of the best available information at the time of the
action. It is possible that federally funded or assisted projects
affecting listed species outside their designated critical habitat
areas could jeopardize those species. Similarly, critical habitat
designations made on the basis of the best available information at the
time of designation will not control the direction and substance of
future recovery plans, habitat conservation plans, or other species
conservation planning and recovery efforts if new information available
to these planning efforts calls for a different outcome.
Prudency Determination
Section 4(a)(3) of the Act and implementing regulations (50 CFR
424.12) require that, to the maximum extent prudent and determinable,
we designate critical habitat at the time a species is listed as
endangered or threatened. Regulations at 50 CFR 424.12(a)(1) state that
the designation of critical habitat is not prudent when one or both of
the following situations exist: (1) The species is threatened by taking
or other activity and the identification of critical habitat can be
expected to increase the degree of threat to the species or (2) such
designation of critical habitat would not be beneficial to the species.
In our February 27, 1998, notice of decision, we determined that
the
[[Page 39112]]
designation of critical habitat was not prudent for the Gulf sturgeon
because such designation would not be beneficial to the species.
However, on March 15, 2001, the United States Court of Appeals for the
Fifth Circuit determined that this ``not prudent'' determination was
made erroneously, and ordered us to reconsider it (Sierra Club v. U.S.
Fish and Wildlife Service, 245 F.3d 434). Accordingly, we withdraw our
previous determination that designation of critical habitat will not
benefit the Gulf sturgeon.
In reconsidering whether designation of critical habitat for the
Gulf sturgeon will be prudent, we find that designation will be clearly
beneficial to the species. Critical habitat will primarily benefit the
sturgeon through the Act's consulting mechanism under section 7 of the
Act. If critical habitat is designated for the Gulf sturgeon, other
Federal agencies will be required to consult with us on actions they
carry out, fund, or authorize, to ensure that their actions will not
destroy or adversely modify critical habitat. In this way, a critical
habitat designation will protect areas that are necessary for the
conservation of the species. It may also serve to enhance awareness
within Federal agencies and the general public of the importance of
Gulf sturgeon habitat and the need for special management
considerations.
A designation of critical habitat will provide Federal agencies
with a clearer indication as to when consultation under Section 7 of
the Act is required, particularly in cases where the action would not
result in direct mortality, injury or harm to individuals of the
species (e.g., an action occurring within the critical habitat area
when or where the Gulf sturgeon is not present). The critical habitat
designation, in describing the essential features of the habitat, will
also help determine which activities conducted outside the designated
area are subject to section 7 consultation (e.g., activities that may
affect essential features of the designated area). For example,
disposal of waste material in water adjacent to a critical habitat area
may affect an essential feature (water quality) of the designated
habitat and so would be subject to the provisions of section 7.
A critical habitat designation will also assist Federal agencies in
planning future actions because it establishes, in advance, those
habitats that will be given an additional review in section 7
consultations. This is particularly true in cases where there are
alternative areas that would provide for the conservation of the
species and the success of the action. With a designation of critical
habitat, potential conflicts between Federal actions and listed species
can be identified and possibly avoided early in the agency's process.
It is true that we are already working with Federal and State
agencies, and private individuals and organizations, in carrying out
conservation activities for the Gulf sturgeon, such as conducting
population surveys and assessing habitat conditions. It is also true
that these entities are fully aware of the distribution, status, and
habitat requirements for the Gulf sturgeon, as they are currently
known. However, as discussed above, some additional educational and
informational benefit will result from designation.
Though the identification of known spawning habitat in this
proposed rule may increase illegal harvest, we currently have no
knowledge that illegal harvest is or has been an issue with the Gulf
sturgeon. Since the States of Louisiana, Mississippi, Alabama, and
Florida have deemed harvest illegal since the 1980s, and we found no
records of illegal harvest during our literature review or in
discussions with researchers, we have found no evidence that
identification of Gulf sturgeon critical habitat would increase the
degree of threat to the species. Therefore, we propose that designation
of critical habitat is prudent for the Gulf sturgeon.
Methods and Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act and its implementing
regulations (50 CFR 424.12), this proposal is based on the best
scientific information available concerning the species' present and
historical range, habitat, biology, and threats. In preparing this
rule, we reviewed and summarized the current information available on
the Gulf sturgeon, including the physical and biological features that
are essential for the conservation of the species (see ``Primary
Constituent Elements'' section), and identified the areas containing
these features. The information used includes known locations; our own
site-specific species and habitat information; State-wide Geographic
Information System (GIS) coverages (e.g., land ownership, bathymetry
(the measurement of depths of water in oceans, seas, and lakes), and
estuarine substrates); the final listing rule for the Gulf sturgeon;
recent biological surveys and reports; peer-reviewed literature; our
recovery plan; discussions and recommendations from Gulf sturgeon
experts; and information received during Gulf sturgeon recovery
meetings. The Gulf Sturgeon Recovery/Management Plan (FWS et al. 1995)
contains valuable biological information, and it is cited throughout
this document. However, the state of our knowledge regarding Gulf
sturgeon biology and distribution has changed markedly since
publication of the recovery plan for this species. The recovery
criteria put forth in this recovery plan were deemed preliminary and
may now warrant revision in light of new information. As a result of
recent research and survey efforts directed towards this species,
substantial portions of the biological information presented in the
recovery plan are now dated or obsolete. Thus, although the recovery
plan is a valuable source of information, it is not the final authority
on the natural history and distribution of this species.
In the past, we had assumed, based on the information available at
the time, that unoccupied habitat would be necessary for the recovery
of the Gulf sturgeon. Since approval of the recovery plan in 1995 and
our 1998 not prudent finding, we have collected new biological
information on this species. We have analyzed what is necessary for the
conservation of the Gulf sturgeon, as described above, and based on the
best scientific information available at this time, we have determined
that unoccupied habitat is not essential to the conservation of the
Gulf sturgeon.
Determining the Scale of the Proposed Designation
We first evaluated the Gulf sturgeon in the context of its current
distribution throughout the historic range to determine what portion of
the range must be conserved to ensure recovery of the species. We
considered several factors in this evaluation--(1) Maintaining overall
genetic integrity and minimizing the potential for inbreeding, (2)
retaining potential evolutionary importance at the margins of the
species' range by protecting the eastern- and western-most
subpopulations, (3) decreasing the extinction risk of a subpopulation
by protecting adjacent subpopulations that can provide a rescue effect,
if needed, (4) avoiding the potential for subpopulation extirpation
from environmental catastrophes, and (5) protecting sufficient habitat
to support full recovery of the species.
The historic range of the Gulf sturgeon included nine major rivers
and several smaller rivers from the Mississippi River, Louisiana, to
the Suwannee River, Florida, and in marine waters of the Central and
Eastern Gulf of Mexico, south to Tampa Bay (Wooley and Crateau 1985,
FWS et al. 1995).
[[Page 39113]]
Seven of these major river systems continue to support reproducing
subpopulations. These include (from west to east)--the Pearl,
Pascagoula, Escambia, Yellow/Blackwater, Choctawhatchee, Apalachicola,
and Suwannee Rivers.
Gulf sturgeon is listed as a single Distinct Population Segment
(DPS) throughout its range (see policy 61 FR 4722). However, this
species exists as several subpopulations with limited mixing. The Gulf
Sturgeon Recovery/Management Plan (FWS et al. 1995) noted the
importance of identifying and maintaining genetic integrity and
diversity during restoration efforts on Gulf sturgeon. A severe loss of
genetic variability often leads to a noticeable decline in the fitness
of a species (Soul[eacute] 1987). Evidence suggests that peripheral
subpopulations are often genetically and morphologically divergent from
central subpopulations (Lesica and Allendorf 1995). Distinct traits
found in peripheral subpopulations may be crucial to the species,
allowing adaptation in the face of environmental change (Lesica and
Allendorf 1995, Allendorf et al. 1997). In light of these
considerations, we determined that the inclusion of stocks or
subpopulations from both the eastern and the western margins of the
current range were necessary to protect the potential evolutionary
importance of those subpopulations (Scudder 1989, Lesica and Allendorf
1995, Young and Harig 2001).
While telemetry data indicate that Gulf sturgeon from one
genetically distinct drainage occasionally enter another river and also
mix during the winter months in estuarine and marine habitats, a
genetic analysis of tissue samples concluded that Gulf sturgeon exhibit
a strong natal river fidelity, with stocks exchanging less than one
mature female per generation on the average (Waldman and Wirgin 1997).
These low gene flow estimates strongly suggest that natural
recolonization of extirpated subpopulations of Gulf sturgeon would
proceed slowly (Waldman and Wirgin 1997). Semi-isolated subpopulations
are more vulnerable to the effects of demographic and environmental
population fluctuations (Forney and Gilpin 1989, Wahlberg et al. 1996).
Gene flow estimates usually were higher between adjacent stocks,
suggesting that migrants from semi-isolated subpopulations are
exchanged chiefly with neighboring subpopulations (Waldman and Wirgin
1997). The loss of any intermediate subpopulations by a single
environmental catastrophe could seriously limit a species' recovery
(Kautz and Cox 2000, Young and Harig 2001). In light of this, we
determined that it is necessary to propose as critical habitat rivers
used by subpopulations evenly spaced between the western- and eastern-
most limits of the current range. To ensure conservation of the
species, subpopulations must be geographically located so that existing
subpopulations could serve as sources of sturgeon emigration, albeit at
a slow rate (Waldman and Wirgin 1997), to adjacent rivers as their
subpopulations increase and so that they can provide a rescue effect if
an adjacent subpopulation is extirpated (Brown and Kodric-Brown 1977,
Hanski and Gyllenberg 1993, Young and Harig 2001).
Designating critical habitat for only a few subpopulation units, or
for units not spaced in a manner that allows fish to exchange with
other subpopulations, could increase the vulnerability of the species
due to isolation of subpopulations. Protection of a single, isolated,
minimally viable population risks the extirpation or extinction of a
species as a result of harsh environmental conditions, catastrophic
events, or genetic deterioration over several generations (Kautz and
Cox 2000). To reduce the risk of extinction through these processes, it
is important to establish multiple protected subpopulations across the
landscape (Soul[eacute] and Simberloff 1986, Wiens 1996).
Because of these considerations, we reached the conclusion that
this proposal should include critical habitat units within the major
river systems that support the seven currently reproducing
subpopulations (FWS et al. 1995) and associated marine habitats. These
river systems include (from west to east)--the Pearl, Pascagoula,
Escambia, Yellow/Blackwater, Choctawhatchee, Apalachicola, and Suwannee
Rivers. We believe that with proper protection and management, these
units collectively represent habitat necessary to provide for the
conservation of the species. The number, distribution, and range of
Gulf sturgeon subpopulations included in these units is necessary to
protect and sustain this species' genetic integrity and diversity and
to provide a rescue effect, if needed. We believe that these seven
river systems, with their associated estuarine and marine environments,
represent habitat that is essential for the conservation of the Gulf
sturgeon.
Assessing Specific Habitat Areas Essential to the Conservation of Gulf
Sturgeon
Once we determined that the proper scale of the proposed critical
habitat designation should cover the area occupied by the seven
reproducing subpopulations, we evaluated which habitats used by those
seven subpopulations are essential to their conservation. To conduct
this evaluation, we assessed the critical life history components of
Gulf sturgeon as they relate to habitat. Gulf sturgeon use the rivers
for spawning, juvenile feeding, adult resting, and staging, and to move
between the areas that support these components. Gulf sturgeon use the
lower riverine, estuarine, and marine environment during winter months
primarily for feeding, and more rarely, for inter-river migrations.
We then investigated what types of habitat support these life
history components and where these areas of habitat are located. We
evaluated empirical data, published and unpublished literature, and
solicited the views of experts. These habitat components are described
in the ``Primary Constituent Elements'' section of this proposed rule.
We identified known or presumed spawning sites in each of the seven
river systems. Some spawning sites have been conclusively identified;
others are presumed due to the presence of suitable habitat. We
identified known or presumed sites used for resting or staging. We
identified areas where subadult and adult Gulf sturgeon occur during
winter to feed. These areas are primarily in the marine or estuarine
environment; young-of-year and juveniles feed mostly in the riverine
environment. As a component of the above identifications, we gathered
all available data on locations and habitat use of marked (tagged)
fish.
To determine which areas should be proposed as critical habitat, we
then evaluated where the necessary constituent elements of Gulf
sturgeon habitat intersected with areas known to be used by both marked
and unmarked fish. Detailed location data, where available, is included
with each proposed unit description in the ``Critical Habitat Unit
Descriptions'' section of this proposed rule. Because most of the
sturgeon species' upstream movement is for spawning (Bane 1997; J.
Hightower, U.S. Geological Survey (USGS)-Biological Resources Division,
pers. comm. 2002), we have determined that the proposal should include
areas as far upstream as the furthest known or presumed spawning site.
Therefore, in rivers where spawning sites have been confirmed, the
proposed units extend upstream to a geographically identifiable point
such as a river confluence above those sites. In areas where spawning
sites are presumed but not confirmed, we have included river reaches
that contain the primary
[[Page 39114]]
constituent elements necessary for spawning (e.g., appropriate
substrate, and water quality and quantity), if those areas occur within
close proximity of Gulf sturgeon historic and/or current sightings or
captures, and if they are still accessible to sturgeon (e.g., not
blocked by dams). The proposed riverine critical habitat units include
areas that continue to offer at least periodic passage of Gulf sturgeon
to known and presumed spawning sites. Successful reproduction and
recent recruitment have been documented in each riverine unit by eggs,
larvae, and/or juveniles, or by a mixed age structure. We are proposing
to protect spawning habitats from a catastrophic occurrence by
including both the main stem spawning sites and at least one tributary
site.
We have included riverine habitat from the river mouth up to and
including spawning grounds in order to provide sufficient habitat
necessary for the other riverine life stages of Gulf sturgeon while
they reside in the riverine habitats. Habitat necessary for these life
stages includes habitat for summer resting or staging areas, juvenile
feeding, entire young-of-year life cycle, passage throughout the river,
and passage into and out of estuarine habitat. All of the selected
areas are known to be used by Gulf sturgeon for some portion of their
life cycle.
Subadult and adult sturgeon use estuarine and marine areas for
feeding and passage between river systems. Designation of critical
habitat units encompassing estuaries and bays adjacent to the riverine
units discussed above would protect unobstructed passage of sturgeon
from feeding areas to spawning grounds. In evaluating the estuarine and
marine areas, we first reviewed where Gulf sturgeon from the seven
adjacent riverine units have been documented by telemetry relocations
and tag returns from incidental captures. We also considered areas for
which we have Gulf sturgeon sightings and targeted and incidental
capture records. When available, we reviewed habitat data (e.g.,
bathymetry, substrate type, and benthic organisms) associated with
these estuarine and marine systems and compared these data with studies
pertaining to the habitat requirements and preferences of Gulf
sturgeon. We also evaluated data for evidence of critical migratory
pathways between the river systems and the adjacent bays and Gulf of
Mexico that allow Gulf sturgeon to travel to important feeding areas,
as well as allow for the occasional travel to non-natal rivers for
possible spawning and genetic interchange. Where documented
interchanges have occurred, but no telemetry data exist to identify the
migratory path used (e.g., between the Pascagoula River and Yellow
River, the Pascagoula and Choctawhatchee River, and between Suwanee
River and Apalachicola River), we have not proposed a migration route.
We then assessed the Gulf sturgeon's overall use of estuarine and
marine waters and delineated specific critical habitat boundaries.
Migration and feeding may take place via the Gulf Intracoastal
Waterway (GIWW) in some of the proposed units. Portions of the GIWW
that consist primarily of excavated land cuts and canals have been
excluded from this designation because they were not available
historically, and, therefore, are not considered to be evolutionarily
significant.
This proposed designation includes a significant portion, but not
all, of the species' historic range. The fourteen proposed critical
habitat units include riverine main stems and in some cases
tributaries, distributaries (a river branch flowing away from the main
stem in the floodplain) and adjacent estuarine and marine areas that
contain one or more of the primary constituent elements essential for
the conservation of the Gulf sturgeon (see ``Primary Constituent
Elements'' section). The omission of some historically occupied river
drainages and estuarine and marine areas from this proposed critical
habitat designation does not diminish their individual or cumulative
importance to the species. Rather, it is our determination that the
seven riverine units with known spawning and seven associated estuarine
and marine units included in this proposed rule include the habitats
essential for the conservation of the Gulf sturgeon. With unobstructed
passage in the estuarine and marine habitat, the subpopulations within
the proposed designated critical habitat units may eventually populate
presently unoccupied coastal river systems or augment adjacent
surviving small subpopulations.
Although the Mobile River Basin is the largest Gulf of Mexico
drainage east of the Mississippi River, it has been extensively
impounded and modified for navigation. Further, there have been
relatively limited reports of captures and no evidence of reproduction
of Gulf sturgeon from that system for many years. Gulf sturgeon have
been reported from other river systems. Some of these other systems
historically supported a commercial fishery (e.g., Mobile River,
Ochlockonee River) and some may support small reproducing
subpopulations (e.g., Techefuncte River, Ochlockonee River, Mobile
River); however, there is no recent documented spawning and we have no
evidence at this time that these systems are essential to the
conservation of the species. Therefore, we have not proposed them as
critical habitat.
The data available to us are insufficient to support a
determination that Lake Maurepas, Breton and Chandeleur Sounds, the
Mississippi River Delta, St. Louis, Biloxi, Mobile, Perdido, St.
Andrews, St. Joseph, Ochlockonee, or Apalachee Bays are essential to
the conservation of the species. Records within the majority of these
bays are relatively scarce. Although some Gulf sturgeon from the seven
subpopulations may occasionally use these bays for winter feeding,
there are insufficient data to support these bays' regular winter use
or importance and no documented spawning. Therefore, we have not
proposed these bays for designation as critical habitat.
The amount of research and status surveys conducted on many
subpopulations is limited. Because of the limited availability of data
specific to each river system and specific to the Gulf sturgeon's use
of the marine environment, we are aware that habitat other than that
identified in this proposed rule may later be found to be essential to
the conservation of Gulf sturgeon. To the extent feasible, we will
continue, with the assistance of other Federal, State, and private
researchers, to conduct surveys, research, and conservation actions on
the species and its habitat in areas designated and not designated as
critical habitat. If additional information becomes available on the
species' biology, distribution, and threats, we will evaluate the need
to designate additional critical habitat, delete or reduce critical
habitat, or refine the boundaries of critical habitat. Gulf sturgeon
surviving in, or moving to rivers that are not being proposed for
critical habitat will continue to receive protection under the section
7 of the Act jeopardy standard and the section 9 of the Act
prohibitions on take (see ``Critical Habitat'' section).
Primary Constituent Elements
In accordance with sections 3(5)(A)(i) and 4(b)(1)(A) of the Act
and regulations at 50 CFR 424.12, in determining which areas to propose
as critical habitat, we are required to base critical habitat
determinations on the best scientific data available and to focus on
those physical and biological features (primary constituent elements)
that are essential to the conservation of the species and that may
require special management considerations or
[[Page 39115]]
protection. Such requirements include, but are not limited to, space
for individual and population growth and for normal behavior; food,
water, air, light, minerals, or other nutritional or physiological
requirements; cover or shelter; sites for breeding, reproduction, and
rearing of offspring; and habitats that are protected from disturbance
or are representative of the historical geographical and ecological
distribution of a species.
Based on the best available information, primary constituent
elements essential for the conservation of the Gulf sturgeon include
the following:
(1) Abundant prey items, such as detritus, aquatic insects, worms,
and/or molluscs, within riverine habitats for larval and juvenile life
stages; and abundant prey items, such as amphipods, lancelets,
polychaetes, gastropods, ghost shrimp, isopods, molluscs and/or
crustaceans, within estuarine and marine habitats for subadult and
adult life stages.
(2) Riverine spawning sites with substrates suitable for egg
deposition and development, such as limestone outcrops and cut
limestone banks, bedrock, large gravel or cobble beds, marl, soapstone,
or hard clay;
(3) A flow regime (i.e., the magnitude, frequency, duration,
seasonality, and rate-of-change of freshwater discharge over time)
necessary for normal behavior, growth, and survival of all life stages
in the riverine environment, including migration, breeding site
selection, courtship, egg fertilization, resting, and staging, and for
maintaining spawning sites in suitable condition for egg attachment,
egg sheltering, resting, and larval staging;
(4) Water quality, including temperature, salinity, pH, hardness,
turbidity, oxygen content, and other chemical characteristics,
necessary for normal behavior, growth, and viability of all life
stages;
(5) Sediment quality, including texture and other chemical
characteristics, necessary for normal behavior, growth, and viability
of all life stages; and
(6) Safe and unobstructed migratory pathways necessary for passage
within and between riverine, estuarine, and marine habitats.
Need for Special Management Consideration or Protection
An area designated as critical habitat contains one or more of the
primary constituent elements that are essential to the conservation of
the species (see ``Primary Constituent Elements'' section), and that
may require special management considerations or protection. Various
activities in or adjacent to each of the critical habitat units
described in this proposed rule may affect one or more of the primary
constituent elements that are found in the unit. These activities
include, but are not limited to, those listed in the ``Effects of
Critical Habitat'' section as ``Federal Actions That May Affect
Critical Habitat and Require Consultation.'' For example, riverine
spawning sites for Gulf sturgeon must be relatively sediment-free for
successful egg development and may need best management practices
implemented in the watershed upstream to prevent an excessive
accumulation of sediment in these areas. None of the proposed critical
habitat units is presently under special management or protection
provided by a legally operative plan or agreement for the conservation
of the Gulf sturgeon. Therefore, we have determined that the proposed
units may require special management or protection.
Proposed Critical Habitat Designation
The areas proposed for designation as critical habitat for the Gulf
sturgeon provide one or more of the primary constituent elements
described above. Tables 1 and 2 summarize the location and extent of
proposed critical habitat. All of the proposed areas require special
management considerations to ensure their contribution to the
conservation of the Gulf sturgeon. The boundaries of proposed critical
habitat units are described generally below.
Table 1.--Approximate Linear Distance of the Proposed Riverine Critical Habitat Units for the Gulf Sturgeon
[Main stems are listed first and tributaries are indented]
----------------------------------------------------------------------------------------------------------------
River
Critical habitat unit river systems State kilometers River miles
----------------------------------------------------------------------------------------------------------------
1. Pearl (East, West, and all distributaries)... Louisiana/Mississippi............. 616 383
Bogue Chitto................................ .................................. 153 95
2. Pascagoula................................... Mississippi....................... 130 81
Leaf........................................ .................................. 164 102
Bowie....................................... .................................. 24 15
Chickasawhay................................ .................................. 232 144
Big Black Creek............................. .................................. 10 6
3. Escambia Florida/Alabama..................... .................................. 93 58
Conecuh..................................... .................................. 128 79
Sepulga..................................... .................................. 11 7
4. Yellow....................................... Florida/Alabama................... 136 84
Blackwater.................................. .................................. 18 11
Shoal....................................... .................................. 13 8
5. Choctawhatchee............................... Florida/Alabama................... 224 139
Pea......................................... .................................. 92 57
6. Apalachicola................................. Florida........................... 172 107
Brothers.................................... .................................. 23 14
7. Suwannee..................................... Florida........................... 286 178
Withlacoochee............................... .................................. 19 12
---------------------------
Total................................... .................................. 2,544 1,580
----------------------------------------------------------------------------------------------------------------
[[Page 39116]]
Table 2.--Approximate Area of the Proposed Estuarine and Marine Critical Habitat Units for the Gulf Sturgeon
----------------------------------------------------------------------------------------------------------------
Critical habitat unit estuarine and marine
systems State Kilometers\2\ Miles\2\
----------------------------------------------------------------------------------------------------------------
8. Lake Borgne.................................. Louisiana/........................ 718 277
Little Lake................................. Mississippi/...................... 8 3
Lake Pontchartrain.......................... Alabama........................... 763 295
Lake St. Catherine.......................... .................................. 26 10
The Rigolets................................ .................................. 13 5
Mississippi Sound........................... .................................. 1,879 725
MS near shore Gulf.......................... .................................. 160 62
9. Pensacola Bay................................ Florida........................... 381 147
10. Santa Rosa Sound............................ Florida........................... 102 39
11. Near shore Gulf of Mexico................... Florida........................... 442 171
12. Choctawhatchee Bay.......................... Florida........................... 321 124
13. Apalachicola Bay............................ Florida........................... 683 264
14. Suwannee Sound.............................. Florida........................... 546 211
---------------------------
Total................................... .................................. 6,042 2,333
----------------------------------------------------------------------------------------------------------------
Critical Habitat Unit Descriptions
The river reaches within units 1 to 7 proposed as critical habitat
lie within the ordinary high water line. As defined in 33 CFR 329.11,
the ordinary high water line on non-tidal rivers is the line on the
shore established by the fluctuations of water and indicated by
physical characteristics such as a clear, natural line impressed on the
bank; shelving; changes in the character of soil; destruction of
terrestrial vegetation; the presence of litter and debris; or other
appropriate means that consider the characteristics of the surrounding
areas.
The downstream limit of the riverine units is the mouth of each
river. The mouth is defined as rkm 0 (rm 0). Although the interface of
fresh and saltwater, referred to as the saltwater wedge, occurs within
the lower-most reach of a river, for ease in delineating critical
habitat units, we are defining the boundary between the riverine and
estuarine units as rkm 0 (rm 0).
Regulatory jurisdiction in coastal areas extends to the line on the
shore reached by the plane of the mean (average) high water (MHW) (33
CFR 329.12(a)(2)). All bays and estuaries within units 8 to 14,
therefore, lie below the MHW lines. Where precise determination of the
actual location becomes necessary, it must be established by survey
with reference to the available tidal datum, preferably averaged over a
period of 18.6 years. Less precise methods, such as observation of the
``apparent shoreline,'' which is determined by reference to physical
markings, lines of vegetation, may be used only where an estimate is
needed of the line reached by the mean high water.
The term 72 COLREGS is defined as demarcation lines which delineate
those waters upon which mariners shall comply with the International
Regulations for Preventing Collisions at Sea, 1972 and those waters
upon which mariners shall comply with the Inland Navigation Rules (33
CFR 80.01). The waters inside of these lines are Inland Rules waters
and the waters outside the lines are COLREGS waters. These lines are
defined in 33 CFR 80, and have been used for identification purposes to
delineate boundary lines of the estuarine and marine habitat Units 8,
9, 11, and 12.
Unit 1. Pearl River System in St. Tammany and Washington Parishes in
Louisiana and Walthall, Hancock, Pearl River, Marion, Lawrence,
Simpson, Copiah, Hinds, Rankin, and Pike Counties in Mississippi
Unit 1 includes the Pearl River main stem from the spillway of the
Ross Barnett Dam, Hinds and Rankin Counties, Mississippi, downstream to
where the main stem river drainage discharges at its mouth joining Lake
Borgne, Little Lake, or The Rigolets in Hancock County, Mississippi,
and St. Tammany Parish, Louisiana. It includes the main stems of the
East Pearl River, West Pearl River, West Middle River, Holmes Bayou,
Wilson Slough, downstream to where these main stem river drainages
discharge at the mouths of Lake Borgne, Little Lake, or The Rigolets.
Unit 1 also includes the Bogue Chitto River main stem, a tributary of
the Pearl River, from its confluence with Lazy Creek just upstream of
its crossing with Mississippi State Highway 570, Pike County,
Mississippi, downstream to its confluence with the West Pearl River,
St. Tammany Parish, Louisiana. The lateral extent of Unit 1 is the
ordinary high water line on each bank of the associated rivers and
shorelines.
The majority of recent Gulf sturgeon sightings in the Pearl River
drainage have occurred downstream of the Pools Bluff sill on the Pearl
River, near Bogalusa, Washington Parish, Louisiana, and downstream of
the Bogue Chitto sill on the Bogue Chitto River in St. Tammany Parish,
Louisiana. Between 1992 and 1996, 257 Gulf sturgeon were captured from
the Pearl River system (West Middle River, Bogue Chitto River, East
Pearl River, and West Pearl River). The subpopulation was estimated at
292 fish, of which only 2 to 3 percent were adults (Morrow et al.
1998b). The annual mortality rate was calculated to be 25 percent.
Preliminary results from captures between 1992 and 2001 suggest a
stable subpopulation of 430 fish, with approximately 300 adults
(Rogillio et al. in prep.). These Pearl River distributaries are used
for migration to spawning grounds, summer resting holes, and juvenile
feeding. Gulf sturgeon have been captured in all of these
distributaries and all are proposed as critical habitat.
The presence of juvenile Gulf sturgeon (1 to 4 years old) in the
Pearl River system indicates successful spawning at some location in
the Pearl River system. It is believed that the only suitable habitat
for spawning for the Pearl River subpopulation of Gulf sturgeon occurs
above the sills on the Pearl River and the Bogue Chitto River with
access to these areas only during high flows (Morrow et al. 1996,
Morrow et al. 1998a). Bedrock and limestone outcropping that are
typical of Gulf sturgeon spawning areas in other systems do not occur
here. However, within the Pearl drainage, spawning areas likely include
soapstone, hard clay, gravel and rubble areas, and undercut banks
adjacent to these substrates (W. Slack pers. comm. 2001). Although the
Pools Bluff sill blocks
[[Page 39117]]
upstream movement on the Pearl River during periods of low water,
potential spawning sites have been identified upstream of the sill at
various locations between Monticello, Lawrence County, Mississippi, and
the Ross Barnett Dam spillway, Hinds and Rankin Counties, Mississippi
(F. Parauka pers. comm. 2002). Gulf sturgeon have also been recently
reported as far upstream as Jackson, Hinds County, Mississippi (Morrow
et al. 1996, Lorio 2000). The Ross Barnett Dam upstream of Jackson
prevents sturgeon movement further upstream at all flow conditions.
Identified suitable spawning habitat, presence of juvenile fish, and
documented adult captures support our inclusion of the Pearl River up
to the spillway of the Ross Barnett Dam.
The Bogue Chitto sill, located on the Bogue Chitto River near its
confluence with the Pearl River, also hinders movement of Gulf sturgeon
upstream of the sill except during high water flows. Suitable spawning
habitat occurs within the Bogue Chitto upriver of the sill (F. Parauka
pers. comm. 2002, W. Slack pers. comm. 2001) and juvenile, adult and
subadult Gulf sturgeon have been documented on the Bogue Chitto River
as far upstream as McComb, Pike County, Mississippi (D. Oge, Department
of Environmental Quality, pers. comm. 2002; F. Parauka pers. comm.
2002; W. Slack pers. comm. 2001). We, therefore, have proposed as
critical habitat the main stem of the Bogue Chitto River upstream of
Quins Bridge (Mississippi State Highway 570) to its confluence with
Lazy Creek.
Unit 2. Pascagoula River System in Forrest, Perry, Greene, George,
Jackson, Clarke, Jones, and Wayne Counties, Mississippi
Unit 2 includes all of the Pascagoula River main stem and its
distributaries, portions of the Bowie, Leaf, and Chickasawhay
tributaries, and all of the Big Black Creek tributary. It includes the
Bowie River main stem beginning at its confluence with Bowie Creek and
Okatoma Creek, Forrest County, Mississippi, downstream to its
confluence with the Leaf River, Forrest County, Mississippi. The Leaf
River main stem beginning from Mississippi State Highway 588, Jones
County, Mississippi, downstream to its confluence with the Chickasawhay
River, George County, Mississippi is included. The main stem of the
Chickasawhay River from the mouth of Oaky Creek, Clarke County,
Mississippi, downstream to its confluence with the Leaf River, George
County, Mississippi is included. Unit 2 also includes Big Black Creek
main stem from its confluence with Black and Red Creeks, Jackson
County, Mississippi, to its confluence with the Pascagoula River,
Jackson County, Mississippi. All of the main stem of the Pascagoula
River from its confluence with the Leaf and Chickasawhay Rivers, George
County, Mississippi, to the discharge of the East and West Pascagoula
Rivers into Pascagoula Bay, Jackson County, Mississippi, is included.
The lateral extent of Unit 2 is the ordinary high water line on each
bank of the associated rivers and shorelines.
Subpopulation estimates, calculated from sturgeon captures in 1999
and 2000 in the summer holding areas on the Pascagoula River, range
between 162 and 216 individuals (Heise et al. 1999a, Ross et al.
2001b). Due to the sampling technique, these estimates are based
primarily on large fish and do not account for juvenile or subadult
fish (S. Ross, University of Southern Mississippi (USM), pers. comm.
2001).
Gulf sturgeon spawning on the Bowie River was confirmed via egg
collection in 1999 (Slack et al. 1999, Heise et al. 1999a). This is the
only confirmed spawning area in the Pascagoula River drainage.
Downstream, the Bowie River is sometimes used as a summer holding area
(Ross et al. 2001b). Gulf sturgeon have been documented using the area
above the known spawning habitat (Reynolds 1993, W. Slack pers. comm.
2002). Additional suitable spawning habitat has been identified in this
upstream reach (F. Parauka pers. comm. 2002), and since Gulf sturgeon
have rarely been documented upstream of spawning grounds, we have also
included the 19 rkm (12 rmi) of river reach upstream of the confirmed
spawning grounds. Confirmed use for spawning and use as a summer
holding area support the inclusion of the Bowie River as proposed
critical habitat.
Documented sightings of Gulf sturgeon and identified suitable
spawning habitat upstream to Mississippi State Highway 588 (Reynolds
1993, W. Slack pers. comm. 2002, F. Parauka pers. comm. 2002),
confirmed use as a migration corridor, and confirmed use by juvenile
Gulf sturgeon (W. Slack pers. comm. 2002) support the inclusion of the
Leaf River as proposed critical habitat.
Documented sightings of Gulf sturgeon using the Chickasawhay River
(Miranda and Jackson 1987, Reynolds 1993, Ross et al. 2001b) upstream
to Quitman (Ross et al. 2001b), and the presence of apparently suitable
spawning habitat at Quitman (F. Parauka pers. comm. 2002), support the
inclusion of this river reach as proposed critical habitat for
spawning, migration, and juvenile feeding. We have included the
suitable spawning habitat located within .8 rkm (.5 rmi) upstream of
Mississippi State Road 512 and have extended the proposed designation 9
rkm (5.5 rmi) upstream to the confluence with Oaky Creek for ease of
identification.
Gulf sturgeon use the West and East distributaries of the
Pascagoula River during spring and fall migrations (Ross et al. 2001b).
Summer resting areas have been consistently documented on Big Black
Creek and on the Pascagoula River (Ross et al. 2001a and b). Confirmed
use for migration and/or summer resting areas and probable feeding use
by juveniles support our inclusion of these river reaches.
Unit 3. Escambia River System in Santa Rosa and Escambia Counties,
Florida and Escambia, Conecuh, and Covington Counties, Alabama
Unit 3 includes the Conecuh River main stem beginning just
downstream of the spillway of Point A Dam, Covington County, Alabama,
downstream to the Florida State line, where its name changes to the
Escambia River, Escambia County, Alabama, and Escambia and Santa Rosa
Counties, Florida. It includes the entire main stem of the Escambia
River downstream to its discharge into Escambia Bay and Macky Bay,
Escambia and Santa Rosa Counties, Florida. All of the distributaries of
the Escambia River including White River, Little White River, Simpson
River, and Dead River, Santa Rosa County, Florida are included. The
Sepulga River main stem from Alabama County Road 42, Conecuh and
Escambia Counties, Alabama, downstream to its confluence with the
Conecuh River, Escambia County, Alabama, is also included. The lateral
extent of Unit 3 is the ordinary high water line on each bank of the
associated lakes, rivers and shorelines.
Sufficient data are not yet available to estimate historic or
current subpopulation sizes of the Escambia River drainage
subpopulation. Collection and tagging of Gulf sturgeon, monitoring, and
eventual subpopulation estimates are in the initial phases on the
Escambia River in Florida and the Conecuh River in Alabama.
Suitable spawning habitat (Parauka and Giorgianni in prep.) and a
reported larval sighting (N. Craft, Department of Environmental
Protection (DEP), pers. comm. 2001), just below the Point A Dam (221
rkm (137 rmi) on the Conecuh River support inclusion of critical
habitat upstream to the Point A Dam. The Point A Dam prevents sturgeon
movement further upstream at all flow conditions. In addition, spawning
has
[[Page 39118]]
been confirmed between rkm 161 and 170 (rmi 100 and 105.6) (Craft et
al. 2001) on the Conecuh River. The use of the river main stem for
spawning, adult resting areas, juvenile feeding and resting, and the
use for migration to these sites supports our inclusion of the
Escambia/Conecuh River main stem as proposed critical habitat for the
Escambia River subpopulation of Gulf sturgeon.
Historic sightings reported from the 1910s and 1920s, and as
recently as 1991, have been documented in Escambia County, Alabama, on
the Sepulga River (Reynolds 1993). Estes (1991) describes the Sepulga
as having smooth rock walls, and long pools with stretches of rocky
shoals and sandbars. We included the Sepulga River reach upstream to
Alabama County Road 42, Escambia County, Alabama, because it has
suitable spawning habitat and documented sightings.
We believe it is most likely that Gulf sturgeon use the Escambia
River main stem and all the distributaries for exiting and entering the
Escambia/Conecuh River. Gulf sturgeon have been documented to use
distributaries near the river mouth within other systems (e.g.,
Suwannee, Pearl, and Pascagoula River systems) for migration into and
out of riverine habitat. We, therefore, have included all
distributaries on the Escambia River system (i.e., White River, Little
White River, Simpson River, and Dead River) in Unit 3.
Unit 4. Yellow River System in Santa Rosa and Okaloosa Counties,
Florida and Covington County, Alabama
Unit 4 includes the Yellow River main stem from Alabama State
Highway 55, Covington County, Alabama, downstream to its discharge at
Blackwater Bay, Santa Rosa County, Florida. All Yellow River
distributaries (including Weaver River and Skim Lake) discharging into
Blackwater Bay are included. The Shoal River main stem, a Yellow River
tributary, from Florida Highway 85, Okaloosa County, Florida, to its
confluence with the Yellow River, is included. The Blackwater River
from its confluence with Big Coldwater Creek, Santa Rosa County,
Florida, downstream to its discharge into Blackwater Bay is included.
Wright Basin and Cooper Basin, Santa Rosa County, on the Blackwater
River are included. The lateral extent of Unit 4 is the ordinary high
water line on each bank of the associated lakes, rivers and shorelines.
The USGS conducted a subpopulation study in the Yellow River system
during the spring (May to July) and fall (October) of 2001. Based on
the capture of 98 fish in the spring and the capture/recapture of 94
fish that fall, the USGS estimated the subpopulation to consist of 580
Gulf sturgeon of 1 m (3.3 ft) or greater in size (M. Randall, USGS,
pers. comm. 2001). This estimate excludes fish younger than 3 to 4
years of age.
Five distinct limestone outcrops have been documented as possible
spawning sites on the Yellow River, between rkm 43 and 134 (rmi 26.7
and 83.3) (Parauka and Giorgianni in prep.). Several sites consist of
brittle marl and limestone, and others of porous limestone. The lowest
downstream site (rkm 43 (rmi 26.7)) is a primitive rock revetment, a
manmade structure with a fair amount of rock substrate (Craft et al.
2001). In recent years, Alabama State biologists have observed young-
of-year Gulf sturgeon near limestone outcrops 3.2 km (2 mi) south of
Alabama State Highway 55 (136 rkm (84 rmi)) (Craft et al. 2001), which
confirms that reproduction is occurring within this subpopulation. The
river upstream of Alabama State Highway 55 is shallow, sandy, and
creek-like and, therefore, not believed suitable for spawning (M.
Randall pers. comm. 2001; F. Parauka pers.comm. 2001; G. Morgan,
Conecuh National Forest, pers. comm. 2001). Preliminary surveys located
four potential summer resting areas on the Yellow River main stem
(Craft et al. 2001). Recent fish captures and the confirmation of
spawning at the furthest upstream spawning habitat location near
Alabama State Highway 55 support our inclusion of the Yellow River main
stem to Alabama State Highway 55 (136 rkm (84 rmi)) as proposed
critical habitat for the Yellow River subpopulation of Gulf sturgeon.
The inclusion of the Shoal River, from the Yellow River confluence
upstream to the Florida Highway 85 bridge (13 rkm (8 rmi)) , is
supported as proposed critical habitat because it is a confirmed summer
resting area (Lorio 2000). The potential for distributaries Weaver
River and Skim Lake to be used for migration to and from the Yellow
River system (Craft et al. 2001) supports their inclusion as proposed
critical habitat. The current and historic use of deep holes by Gulf
sturgeon on the Blackwater River main stem and between Wright Basin and
Cooper Basin demonstrate the importance of this area for summer resting
and staging (Reynolds 1993, Craft et al. 2001) and support its
inclusion as proposed critical habitat for the Yellow River
subpopulation.
Unit 5. Choctawhatchee River System in Holmes, Washington, and Walton
Counties, Florida and Dale, Coffee, Geneva, and Houston Counties,
Alabama
Unit 5 includes the Choctawhatchee River main stem from its
confluence with the west and east fork of the Choctawhatchee River,
Dale County, Alabama, downstream to its discharge at Choctawhatchee
Bay, Walton County, Florida. The distributaries discharging into
Choctawhatchee Bay known as Mitchell River, Indian River, Cypress
River, and Bells Leg are included. The Boynton Cutoff, Washington
County, Florida, which joins the Choctawhatchee River main stem, and
Holmes Creek, Washington County, Florida, are included. The section of
Holmes Creek from Boynton Cutoff to the mouth of Holmes Creek,
Washington County, Florida, is included. The Pea River main stem, a
Choctawhatchee River tributary, from the Elba Dam, Coffee County,
Alabama, to its confluence with the Choctawhatchee River, Geneva
County, Alabama, is included. The lateral extent of Unit 5 is the
ordinary high water line on each bank of the associated rivers and
shorelines.
Preliminary estimates of the size of the Gulf sturgeon
subpopulation in the Choctawhatchee River system are 2,000 to 3,000
fish over 61 cm (24 inches (in)) total length (F. Parauka pers. comm.
2001).
Biologists have located Gulf sturgeon within .8 rkm (.5 rmi)
downstream of the Elba Dam, Coffee County, Alabama, on the Pea River
(Lorio 2000) and have identified suitable spawning habitat from the
Elba Dam to the Pea River mouth (Parauka and Giorgianni in prep.,
Zehfuss et al. in prep.). The Elba Dam prevents sturgeon movement
further upstream at all flow conditions. This river reach has one
confirmed spawning site, and Gulf sturgeon often use the lower reach
for summer resting (Fox et al. 2000, Hightower et al. in press).
Suitable spawning and resting habitat, confirmed spawning, and young-
of-year and juvenile feeding (F. Parauka pers. comm. 2001) support
inclusion of the Pea River reach as proposed critical habitat.
Five spawning sites and seven resting areas have been identified on
the Choctawhatchee River main stem between the river mouth (0 rkm (0
rmi)) and upstream to 150 rkm (93 rmi) (Hightower et al. in press,
Zehfuss et al. in prep.). Biologists have identified suitable spawning
habitat (limestone outcrops) periodically between 135 rkm (84 rmi) to
the confluence of the West
[[Page 39119]]
Fork Choctawhatchee River and East Fork Choctawhatchee River (224 rkm
(139 rmi)) (H. Blalock-Herod, FWS, pers. comm. 2002; Parauka and
Giorgianni in prep.; Zehfuss et al. in prep.). Fox et al. (2000)
located a male at 150 rkm (93 rmi) and another male in spawning
condition near Newton (214 rkm (133 rmi)) on the Choctawhatchee River,
8 rkm (5 rmi) downstream of the confluence of the West Fork
Choctawhatchee River and East Fork Choctawhatchee River. Since Gulf
sturgeon rarely occur upstream of spawning grounds, we have included up
to the confluence of West Fork Choctawhatchee River and East Fork
Choctawhatchee River for ease of identification and with the
probability of unconfirmed spawning grounds. Suitable habitat,
confirmed spawning, and young-of-year and juvenile feeding support the
inclusion of the Choctawhatchee River main stem as proposed critical
habitat.
No sturgeon have been documented within Holmes Creek, except for
the section that connects the Choctawhatchee River and Boynton Cutoff,
north and south. We have included this river section of Holmes Creek
because it acts as part of the Choctawhatchee River main stem. In 1994,
Gulf sturgeon were captured during March and April at the mouths of
Indian River, Cypress River, and Bells Leg, indicating that sturgeon
probably use these distributaries as migratory corridors to and from
the Choctawhatchee River main stem. All distributaries, including the
Indian River, Cypress River, Bells Leg, and Mitchell River, are
included as proposed critical habitat.
Unit 6. Apalachicola River System in Franklin, Gulf, Liberty, Calhoun,
Jackson, and Gadsen Counties, Florida
Unit 6 includes the Apalachicola River mainstem, beginning from the
Jim Woodruff Lock and Dam, Gadsden and Jackson Counties, Florida,
downstream to its discharge at East Bay or Apalachicola Bay, Franklin
County, Florida. All Apalachicola River distributaries, including the
East River, Little St. Marks River, St. Marks River, Franklin County,
Florida, to their discharge into East Bay and/or Apalachicola Bay are
included. The entire main stem of the Brothers River, Franklin and Gulf
Counties, Florida, a tributary of the Apalachicola River, is included.
The lateral extent of Unit 6 is the ordinary high water line on each
bank of the associated rivers and shorelines.
Based on mark/recapture studies conducted in 1998 and 1999 in the
Apalachicola River downstream of Jim Woodruff Lock and Dam, the summer
subpopulation of subadult and adult Gulf sturgeon was estimated to be
between 270 and 321 individuals (FWS 1998, 1999). Seventy-one sturgeon
were collected in the upper Brothers River, upstream of the Brickyard
Cutoff and downstream of Bearman Creek between June and September 1999
(FWS 1999, Lorio 2000). Gulf sturgeon captured on the Brothers River
have not been included in the Apalachicola River subpopulation size
estimate although they are believed to be part of the subpopulation.
The Gulf sturgeon became restricted to the portion of the
Apalachicola River downstream of the Jim Woodruff Lock and Dam upon the
construction of the dam in the 1950s. Wooley et al. (1982) documented
the capture of two Gulf sturgeon larvae on the Apalachicola River just
downstream of the Jim Woodruff Lock and Dam, thereby confirming
successful spawning up to the dam. Resting aggregations are often seen
at the base of the dam. Seven potential spawning sites have been
identified in the upper Apalachicola River between Highway 20 and the
Jim Woodruff Lock and Dam (120 to 171 km (76 to 106 rmi)) (Parauka and
Giorgianni in prep.). Suitable spawning and resting habitat, confirmed
spawning, and young-of-year and juvenile feeding support inclusion of
the Apalachicola River as proposed critical habitat.
The entire main stem of the Brothers River, a major tributary of
the Apalachicola River, is also included as proposed critical habitat.
Spawning has not been documented within this tributary, but an
important resting area is located in the uppermost section of the
Brothers River between Brickyard Cutoff and Bearman Creek (FWS 1999,
Lorio 2000). Sturgeon use the lower Brothers River as a resting and
possible osmoregulation area (staging) before migrating into the
estuarine and marine habitats for winter feeding (Wooley and Crateau
1985). The Apalachicola River distributaries, including the East River,
St. Marks River and Little St. Marks River, are included, based on
information derived from other systems. Gulf sturgeon tend to use more
than just the main stem for migration into and out of the river systems
(e.g., Suwannee, Choctawhatchee, and Pearl River systems).
Unit 7. Suwannee River System in Hamilton, Suwannee, Madison,
Lafayette, Gilchrist, Levy, Dixie, and Columbia Counties, Florida
Unit 7 includes the Suwannee River main stem, beginning from its
confluence with Long Branch Creek, Hamilton County, Florida, downstream
to the mouth of the Suwannee River. It includes all the Suwannee River
distributaries, including the East Pass, West Pass, Wadley Pass, and
Alligator Pass, Dixie and Levy Counties, Florida, to their discharge
into the Suwannee Sound or the Gulf of Mexico. The Withlacoochee River
main stem from Florida State Road 6, Madison and Hamilton Counties,
Florida, to its confluence with the Suwannee River is included. The
lateral extent of Unit 7 is the ordinary high water line on each bank
of the associated rivers and shorelines.
The Suwannee River supports the largest Gulf sturgeon subpopulation
among the coastal rivers of the Gulf of Mexico (Huff 1975, Gilbert
1992). Sulak and Clugston (1999) reported 5,344 uniquely tagged
Suwannee River sturgeons from 1986 to 1998. Multiple models using
various age classes have been used to estimate the subpopulation size
of Gulf sturgeon on the Suwannee River system. Chapman et al. (1997)
estimated the subpopulation at 3,152 fish greater than age 6. Sulak and
Clugston's (1999) estimate was 7,650 individuals greater than 61 cm (24
in) total length and older than age 2. Pine et al. (2001) estimated the
Suwannee River subpopulation at 5,500 individuals ages 2 to 25. Based
on intensive egg sampling efforts conducted between 1993 and 1998,
Sulak and Clugston (1999) estimated that 30 to 90 female fish spawn per
year.
Marchant and Shutters (1996) collected two Gulf sturgeon eggs in
April 1993 on the Suwannee River. These were the first eggs reported
from the wild for Gulf sturgeon. Between 1993 and 1998, three spawning
sites were confirmed with the collection of Gulf sturgeon eggs on
artificial substrate samplers (Marchant and Shutters 1996, Sulak and
Clugston 1999). Young-of-year have been documented using between rkm 10
to 237 (rmi 6.2 to 147.3) on the Suwannee River main stem (Carr et al.
1996a, Sulak and Clugston 1999). The young-of-year sturgeon located at
rkm 237 (rmi 147.3), north of Interstate 75, by Sulak and Clugston
(1999) was likely spawned in the river as far upstream as Big Shoals
and was captured on its way downstream (M. Randall pers. comm. 2002).
It is believed that the farthest upstream that sturgeon spawn during
high water is Big Shoals, near White Springs, Hamilton and Columbia
Counties, Florida, but adult sturgeon are probably unable to move
upstream of Big Shoals (Huff 1975; K. Sulak, USGS, pers. comm. 2002; M.
Randall pers. comm. 2002).
[[Page 39120]]
Suitable spawning habitat has been identified upstream to Big Shoals
(Huff 1975; H. Blalock-Herod, FWS, pers. comm. 2002). Foster and
Clugston (1997) located five major resting areas throughout the
Suwannee River. A deep river bend and a shallow sandy section were
characteristic features of the resting areas (Foster and Clugston
1997). Confirmed use for spawning, identified and probable spawning
habitat upstream to Big Shoals, young-of year and juvenile feeding, and
summer resting support the inclusion of the Suwannee River as proposed
critical habitat. For ease of identification, the Suwannee River has
been included upstream of Big Shoals .8 rkm (.5 rmi) to its confluence
with Long Branch Creek.
Adult Gulf sturgeon sightings and suitable spawning habitat on the
lower Withlacoochee River near Florida State Road 141, Hamilton and
Madison Counties, Florida, support the inclusion of this area as
proposed critical habitat. We have included shoals (5 rkm (3 rmi))
located just upstream of where sturgeon have been observed as possible
spawning habitat, and have stopped at Florida State Road 6 (14 rkm (9
rmi)), upstream from the shoals, for ease of identification.
The Suwannee River branches near its mouth into the East Pass and
West Pass. Gulf sturgeon adults use the East Pass and West Pass for
emigration and immigration (Mason and Clugston 1993, Edwards et al. in
prep.). The West pass is divided into two primary channels--Wadley
Pass, connected to the Gulf of Mexico by a straight dredged channel
across the northern portion of the Sound, and Alligator Pass, used by
juveniles (Huff 1975), connected to the Gulf of Mexico by an undredged,
natural channel. Confirmed use of the East Pass, West Pass, and
Alligator Pass, and probable use of the Wadley Pass by adult and
juvenile Gulf sturgeon for migration and feeding support the inclusion
of all distributaries of the Suwannee River as proposed critical
habitat.
Unit 8. Lake Pontchartrain, Lake St. Catherine, The Rigolets, Little
Lake, Lake Borgne, and Mississippi Sound in Jefferson, Orleans, St.
Tammany, and St. Bernard Parish, Louisiana, Hancock, Jackson, and
Harrison Counties in Mississippi, and in Mobile County, Alabama
Unit 8 encompasses Lake Pontchartrain east of the Lake
Pontchartrain Causeway, all of Little Lake, The Rigolets, Lake St.
Catherine, Lake Borgne, including Heron Bay, and the Mississippi Sound.
Proposed critical habitat follows the shorelines around the perimeters
of each included lake. The Mississippi Sound includes adjacent open
bays including Pascagoula Bay, Point aux Chenes Bay, Grand Bay, Sandy
Bay, and barrier island passes, including Ship Island Pass, Dog Keys
Pass, Horn Island Pass, and Petit Bois Pass. The northern boundary of
the Mississippi Sound is the shoreline of the mainland between Heron
Bay Point, Mississippi and Point aux Pins, Alabama. Proposed critical
habitat excludes St. Louis Bay, north of the railroad bridge across its
mouth; Biloxi Bay, north of the U.S. Highway 90 bridge; and Back Bay of
Biloxi. The southern boundary follows along the broken shoreline of
Lake Borgne created by low swampy islands from Malheureux Point to Isle
au Pitre. From the northeast point of Isle au Pitre, the boundary
continues in a straight north-northeast line to the point 1 nautical
mile (nm) (1.9 km) seaward of the western most extremity of Cat Island
(30 deg.13'N, 89 deg.10'W). The southern boundary continues 1 nm (1.9
km) offshore of the barrier islands and offshore of the 72 COLREGS
lines at barrier island passes (defined at 33 CFR 80.815(c), (d) and
(e)) to the eastern boundary. Between Cat Island and Ship Island there
is no 72 COLREGS line. We therefore, have defined that section of the
southern boundary as 1 nm (1.9 km) offshore of a straight line drawn
from the southern tip of Cat Island to the western tip of Ship Island.
The eastern boundary is the line of longitude 88 deg.18.8'W from its
intersection with the shore (Point aux Pins) to its intersection with
the southern boundary. The lateral extent of Unit 8 is the MHW line on
each shoreline of the included water bodies or the entrance to rivers,
bayous, and creeks.
The Pearl River and its distributaries flow into The Rigolets,
Little Lake, and Lake Borgne, the western extension of Mississippi
Sound. The Rigolets connect Lake Pontchartrain and Lake St. Catherine
with Little Lake and Lake Borgne. The Pascagoula River and its
distributaries flow into Pascagoula Bay and Mississippi Sound.
This proposed unit provides juvenile, subadult and adult feeding,
resting, and passage habitat for Gulf sturgeon from the Pascagoula and
the Pearl River subpopulations. One or both of these subpopulations
have been documented by tagging data, historic sightings, and
incidental captures as using Pascagoula Bay, The Rigolets, the eastern
half of Lake Pontchartrain, Little Lake, Lake St. Catherine, Lake
Borgne, Mississippi Sound, within 1 nm (1.9 km) of the nearshore Gulf
of Mexico adjacent to the barrier islands and within the passes (Davis
et al. 1970, Reynolds 1993, Rogillio 1993, Morrow et al. 1998a, Ross et
al. 2001a, Rogillio et al. in prep., F. Parauka pers. comm. 2002).
Substrate in these areas ranges from sand to silt, all of which contain
known Gulf sturgeon prey items (Abele 1986, American Fisheries Society
1989, Menzel, 1971).
The Rigolets is a 11.3 km (7 mi) long and about 0.6 km (0.4 mi)
wide passage connecting Lake Pontchartrain and Lake Borgne (U.S.
Department of Commerce (USDOC) 2002). This brackish water area is used
by adult Gulf sturgeon as a staging area for osmoregulation and for
passage to and from wintering areas (Rogillio et al. in prep.). Lake
St. Catherine is a relatively shallow lake with depths averaging
approximately 1.2 m (4 ft), connected to The Rigolets by Sawmill Pass.
Bottom sediments in Sawmill Pass are primarily silt, while Lake
Catherine's bottom is composed of silt and sand (Barett 1971).
Incidental catches of Gulf sturgeon are documented from Lake St.
Catherine and Sawmill Pass (Reynolds 1993; H. Rogillio, Louisiana
Department of Wildlife and Fisheries, pers. comm. 2002). Based on the
proximity of Little Lake, Lake St Catherine, and Sawmill Pass to The
Rigolets and Pearl River, we believe these areas are also used for
staging and feeding and, therefore, are including them with the
Rigolets as proposed critical habitat.
Rogillio (1990) and Morrow et al. (1996) indicated that Lake
Pontchartrain and Lake Borgne were used by Gulf sturgeon as wintering
habitat, with most catches during late September through March. Lake
Pontchartrain is 57.9 km (36 mi) long, 35.4 km (22 mi) wide at its
widest point, and 3 to 4.9 m (10 to 16 ft) deep (USDOC 2002). Morrow et
al. (1996) documented Gulf sturgeon from the Pearl River system using
Lake Pontchartrain (verified by tags) and summarized existing Gulf
sturgeon records, which indicated greater use of the eastern half of
Lake Pontchartrain. Although Rogillio et al. (in prep.) did not
relocate any of their sonic tagged adult Gulf sturgeon in Lake
Pontchartrain, H. Rogillio (pers. comm. 2002) believes the eastern part
of this lake to be an important winter habitat for juveniles and
subadults based on previous records. We believe that Gulf sturgeon feed
in Lake Pontchartrain during the winter. The Lake Pontchartrain
Causeway, twin toll highway bridges, extends 33.6 km (20.9 mi) across
Lake Pontchartrain from Indian Beach on the south shore to Lewisburg
and Mandeville on the north shore. Sediment data from Lake
Pontchartrain indicate sediments have a
[[Page 39121]]
greater sand content east of the causeway (Barret 1976, Manheim et al.
2002). Most records from Lake Pontchartrain are located east of the
causeway, with concentrations near Bayou Lacombe and Goose Point, both
on the eastern north shore (Reynolds 1993, Morrow et al. 1996). Gulf
sturgeon have also been documented west of the causeway, generally near
the mouths of small river systems (Davis 1970). We have excluded the
western half of Lake Pontchartrain, however, because we believe that
the sturgeon using these areas are coming from these western
tributaries and not the Pearl River.
Lake Pontchartrain connects by The Rigolets with Lake Borgne. Lake
Borgne, the western extension of Mississippi Sound, is partly separated
from Mississippi Sound by Grassy Island, Half Moon (Grand) Island and
Le Petit Pass Island. Lake Borgne is approximately 14.3 km (23 mi) in
length, 3 to 6 km (5 to 10 mi) in width and 1.8 to 3 m (6 to 10 ft) in
depth (USDOC 2002). Most of Lake Borgne sediment is clay and silt
(Barett 1971). Many Gulf sturgeon were anecdotally reported as taken
incidentally in shrimp trawls in Lake Borgne 0.6 to 1.2 km (1 to 2 mi)
south of the Pearl River between August and October from the 1950s
through the 1980s (Reynolds 1993). There are twenty-two additional
records of Gulf sturgeon in Lake Borgne (D. Walther, FWS, pers. comm.
2002). Known locations are spread out around the perimeter of the Lake,
including at the mouth of The Rigolets, Violet Canal, Bayou Bienvenue,
Polebe, Alligator Point, and at Half Moon Island (Reynolds 1993). We
are proposing to include all of Lake Borgne as critical habitat.
The Mississippi Sound is separated from the Gulf of Mexico by a
chain of barrier islands, including Cat, Ship, Horn, and Petit Bois
Islands. Natural depths of 3.7-5.5 m (12 to 18 ft) are found throughout
the Sound and a channel 3.7 m (12 ft) deep has been dredged where
necessary from Mobile Bay to New Orleans (USDOC 2001). Incidental
captures and recent studies confirm that both Pearl River and
Pascagoula River adult Gulf sturgeon winter in the Mississippi Sound,
particularly around barrier islands and barrier islands passes
(Reynolds 1993, Ross et al. 2001a, Rogillio et al. in prep.).
Pascagoula Bay is adjacent to the Mississippi Sound. Gulf sturgeon
exiting the Pascagoula River move both east and west, with telemetry
recoveries as far east as Dauphin Island and as far west as Cat Island
and the entrance to Lake Pontchartrain, Louisiana (Ross et al. 2001a).
Gulf sturgeon from the Pearl River subpopulation have been documented
scattered between Cat Island, Ship Island, Horn Island, and east of
Petit Bois Islands to the Alabama State line (Rogillio et al. in
prep.). Gulf sturgeon have also been documented within 1 nm (1.9 km)
off the barrier islands of Mississippi Sound. We, therefore, have
included 1 nm (1.9 km) offshore of the barrier islands of Mississippi
Sound. Habitat used by Gulf sturgeon in the vicinity of the barrier
islands is 1.9 to 5.9 m (6.2 to 19.4 ft) deep (average 4.2 m (13.8
ft)), with clean sand substrata (Heise et al. 1999b, Ross et al. 2001a,
Rogillio et al. in prep.). Preliminary data from substrate samples
taken in the barrier island areas indicate that all samples contained
lancelets (Ross et al. 2001a). Inshore locations where Gulf sturgeon
were located (Deer Island, Round Island) were 1.9 to 2.8 m (6.2 to 9.2
ft) deep and all had mud (mostly silt and clay) substrata (Heise et al.
1999b) typical of substrates supporting known Gulf sturgeon prey.
Unit 9. Pensacola Bay System in Escambia and Santa Rosa Counties,
Florida
Unit 9 includes Pensacola Bay and its adjacent main bays and coves.
These include Big Lagoon, Escambia Bay, East Bay, Blackwater Bay, Bayou
Grande, Macky Bay, Saultsmar Cove, Bass Hole Cove, and Catfish Basin.
All other bays, bayous, creeks, and rivers are excluded at their
mouths. The western boundary is the Florida State Highway 292 Bridge
crossing Big Lagoon to Perdido Key. The southern boundary is the 72
COLREGS line between Perdido Key and Santa Rosa Island (defined at 33
CFR 80.810 (g)). The eastern boundary is the Florida State Highway 399
Bridge at Gulf Breeze, Florida. The lateral extent of Unit 9 is the MHW
line on each shoreline of the included water bodies.
The Pensacola Bay system includes five interconnected bays,
including Escambia Bay, Pensacola Bay, Blackwater Bay, East Bay, and
the Santa Rosa Sound. The Santa Rosa Sound is addressed separately in
proposed unit 10. The Escambia River and its distributaries (Little
White River, Dead River, and Simpson River) empty into Escambia Bay,
including Bass Hole Cove, Saultsmar Cove, and Macky Bay. The Yellow
River empties into Blackwater Bay. The entire system discharges into
the Gulf of Mexico, primarily through a narrow pass at the mouth of
Pensacola Bay.
The Pensacola Bay system provides winter feeding and migration
habitat for Gulf sturgeon from the Escambia River and Yellow River
subpopulations. Over the past four years, researchers of the Florida
Department of Environment Protection (FDEP) have conducted tracking
studies in the Pensacola Bay system to observe Gulf sturgeon winter
migrations. They have identified specific areas in the bays where
Escambia River and Yellow River Gulf sturgeon collect, or migrate
through, during the fall and winter season. These studies also
identified two main habitat types where Gulf sturgeon concentrate
during winter months. Movement is generally along the shoreline area of
Pensacola Bay. Gulf sturgeon showed a preference for several areas in
the bay, including Redfish Point, Fort Dickens, and Escribano Point,
near Catfish Basin (FWS 1998, Craft et al. 2001). Sandy shoal areas,
located along the south and east side of Garcon Point, south shore of
East Bay (Redfish Point area) and near Fair Point, appear to be
commonly used, especially in the fall and early spring. During
midwinter, common areas are in deep holes located north of the barrier
island at Ft. Pickens, south of the Pensacola Naval Air Station, and at
the entrance of Pensacola Pass. The depth in these areas ranges from 6
to 12.1 m (20 to 40 ft). Other areas where tagged fish were frequently
located include Escribano Point, near Catfish Basin, and the mouth of
the Yellow River. Previous incidental captures of Gulf sturgeon have
been recorded in Pensacola Bay, Big Lagoon, and Bayou Grande (Reynolds
1993, Lorio 2000).
Unit 10. Santa Rosa Sound in Escambia, Santa Rosa, and Okaloosa
Counties, Florida
Unit 10 includes the Santa Rosa Sound, bounded on the west by the
Florida State Highway 399 bridge in Gulf Breeze, Florida. The eastern
boundary is the U.S. Highway 98 bridge in Fort Walton Beach, Florida.
The northern and southern boundaries of Unit 10 are formed by the
shorelines to the MHW line or by the entrance to rivers, bayous, and
creeks.
The Santa Rosa Sound is a lagoon between the mainland and Santa
Rosa Island that connects Pensacola Bay in the west with Choctawhatchee
Bay in the east. The Sound extends approximately 57.9 km (35.9 mi)
along an east-west orientation, varying in width between 0.32 and 3.5
km (0.2 to 2.2 mi) (FDEP 1993). The Intracoastal Waterway transects the
sound. The Santa Rosa Sound is proposed as critical habitat because we
believe it provides one continuous migratory pathway between
Choctawhatchee Bay, Pensacola Bay, and the Gulf of Mexico for feeding
and genetic interchange. Within the last 3,000 years, periodic shoaling
closed the opening of
[[Page 39122]]
Choctawhatchee Bay to the Gulf of Mexico. For many years, the Santa
Rosa Sound provided the only way for Choctawhatchee River Gulf sturgeon
to migrate to the Gulf of Mexico (Wakeford 2001). Recent locations of
subadult and adult Gulf sturgeon within the Santa Rosa Sound confirm
its present use by the Choctawhatchee River subpopulations (F. Parauka
pers. comm. 2002, Fox et al. in press). The Escambia and Yellow River
subpopulations may also use this area due to its close proximity. Gulf
sturgeon have been located mid-channel and in shoreline areas in 2 to
5.2 m (6.6 to 17.1 ft) depths and sand substrate. The approximate
length of the proposed critical habitat unit is 52.8 km (33 miles).
Bridges were chosen as the eastern and western boundaries for ease in
identification. Any portion of the sound not included in this unit is
captured by the adjacent critical habitat units.
Unit 11. Florida Nearshore Gulf of Mexico Unit in Escambia, Santa Rosa,
Okaloosa, Walton, Bay, and Gulf Counties in Florida
Unit 11 includes a portion of the Gulf of Mexico as defined by the
following boundaries. The western boundary is the line of longitude
87 deg.20.0' W (approximately 1 nm (1.9 km) west of Pensacola Pass)
from its intersection with the shore to its intersection with the
southern boundary. The northern boundary is the MHW of the mainland
shoreline and the 72 COLREGS lines at passes as defined at 30 CFR
80.810 (a-g). The southern boundary is 1 nm (1.9 km) offshore of the
northern boundary. The eastern boundary is the line of longitude
85 deg.17.0' W from its intersection with the shore (near Money Bayou
between Cape San Blas and Indian Peninsula) to its intersection with
the southern boundary.
Unit 11 includes winter feeding and migration habitat for Gulf
sturgeon from the Yellow River, Choctawhatchee River, and Apalachicola
River subpopulations. Telemetry relocation data suggest that these
subpopulations feed in nearshore Gulf of Mexico waters between their
natal river systems (Fox et al. in press, F. Parauka pers. comm. 2002).
Gulf sturgeon from the Choctawhatchee River subpopulation have been
documented both east and west of Choctawhatchee Bay (F. Parauka pers.
comm. 2002, Fox et al. in press). In the winter of 2001-2002, the USGS
and FWS attached pop-up satellite tags to 20 Gulf sturgeon (12 from the
Suwannee River, 4 from the Choctawhatchee River, 2 from the
Apalachicola, and 2 from the Yellow River) to investigate winter
feeding migrations in the Gulf of Mexico. Due to a design flaw, errors
in attachment, or sturgeon's ability to successfully knock the tags
off, the tags failed to report reliable data with only two exceptions.
One of the Choctawhatchee-tagged Gulf sturgeon was located in Hogtown
Bayou in Choctawhatchee Bay. This provided no new information, as we
already knew that some adult Gulf sturgeon overwinter in this bayou.
The other operating tag, however, was one that had been attached to a
Yellow River Gulf sturgeon. Sonic tracking in the vicinity of that
Yellow River Gulf sturgeon led to the relocation of other sonic tagged
Gulf sturgeon. Sonic-tagged individuals from three different
subpopulations (Choctawhatchee, Yellow, and Apalachicola Rivers) were
relocated on multiple occasions in close proximity to one another,
suggesting an important feeding area just offshore of Mexico Beach,
Crooked Island East, and Crooked Island West over sand substrate. The
data suggest that Gulf sturgeon from the Yellow River, Choctawhatchee
River, and Apalachicola River remain within 1.6 km (1 mi) of the
coastline between these river systems (F. Parauka pers. comm. 2002).
Examination of bathymetry data along the Gulf of Mexico coastline
between the Pensacola Bay and Apalachicola Bay reveals that depths of
less than 6 m (19.7 ft), within which Gulf sturgeon are generally
found, are all contained within 1 nm (1.9 km) from shore. Gulf
nearshore substrate contains unconsolidated, fine-medium grain sands
which support crustaceans such as mole crabs, sand fleas, various
amphipod species, and lancelets (Menzel 1971, Abele 1986, American
Fisheries Society 1989). Based on their direction of movement over
time, it appeared these Gulf sturgeon were feeding in the nearshore
Gulf of Mexico on route to their natal rivers. Given this information
we are including the nearshore (up to 1 nm (1.9 km)) Gulf of Mexico
waters between Pensacola and Apalachicola Bays.
Unit 12. Choctawhatchee Bay in Okaloosa and Walton Counties, Florida
Unit 12 includes the main body of Choctawhatchee Bay, Hogtown
Bayou, Jolly Bay, Bunker Cove, and Grassy Cove. All other bayous,
creeks, and rivers are excluded at their mouths/entrances. The western
boundary is the U.S. Highway 98 bridge at Fort Walton Beach, Florida.
The southern boundary is the 72 COLREGS line across East (Destin) Pass
as defined at 33 CFR 80.810(f). The lateral extent of Unit 12 is the
MHW line on each shoreline of the included water bodies.
Choctawhatchee Bay provides important habitat for maintaining the
health of subadult and adult Gulf sturgeon as evidenced by a large
number of Gulf sturgeon overwintering in the system (FWS 1997, 1998;
Parauka et al. in press). The Choctawhatchee Bay offers a feeding area
for both subadults and adults (FWS 1998, Fox et al. in press). Tagged
subadults showed a preference for shoreline habitats which are
predominated by sandy substrates, low salinity and water depths less
than 3 m (10 ft) (FWS 1997, 1998; Parauka et al. in press). Most adult
Gulf sturgeon were found in shallow water (2 to 4 m (6.6 to 13.1 ft))
with predominantly (greater than 80 percent) sandy sediment (Fox et al.
in press). Ghost shrimp, a component of the sturgeon diet, are
typically found in substrates ranging from sandy mud to organic silty
sand (Felder and Lovett 1989), and their densities were greatest
nearshore along the middle and eastern portions of the Choctawhatchee
Bay (Heard et al. 2000), the area frequented by the Gulf sturgeon (Fox
et al. in press). We include the deeper central portion of the Bay in
Unit 12 as proposed critical habitat because the Gulf sturgeon are
known |
