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NFC: Okaloosa Darter INFO
Source: Endangered and Threatened Species of the Southeastern United
States (The Red Book) FWS Region 4 -- As of 2/91
OKALOOSA DARTER
(Etheostoma okaloosae)
FAMILY: Percidae
STATUS: Endangered throughout its range, Federal Register, June 4, 1973
DESCRIPTION: The Okaloosa darter is a small, elongate, slightly
compressed darter, adults ranging 27-49 millimeters standard length
(Mettee and Crittenden 1979; Ogilvie 1980). The head is of moderate
proportion with a medium-size lateral eye and terminal mouth. The spinous
dorsal is narrowly separated from the rayed dorsal; the caudal fin is
round to truncate. Scale and fin ray counts are in Collette and Yerger
(1962). Immature aquatic insect larvae comprise the bulk of this species'
diet, principally midges, mayflies, and caddisflies (Ogilvie 1980).
REPRODUCTION AND DEVELOPMENT: The spawning season is protracted, lasting
from March to October, but with greatest activity occurring in April
(Ogilvie 1980). Spawning occurs in beds of clean, current-swept
macrophytes. A single egg is deposited from each spawning act; parental
care is absent. Fecundity is very low - mean mature ova were only 29
(Ogilvie 1980). Development is essentially unknown. Mettee and Crittenden
(1979) reported a newly-hatched prolarva was 4.9 millimeters in total
length.
RANGE AND POPULATION LEVEL: This darter is restricted to six tributary
systems of the lower Choctawhatchee Bay drainage, Okaloosa and Walton
counties, western Florida (Figure 1). The tributary systems drain two
bayous, Boggy Bayou (Toms, Turkey, and Mill creeks) and Rocky Bayou
(Swift, Turkey, and Rocky creeks), totaling 9O.9 and 151.9 stream miles,
respectively. Ninety-four percent of the darter's range drains Eglin Air
Force Base, the largest non-nuclear weapons testing facility in North
America. The darter's exact, current population level is unknown, but
estimates range from 1,5OO to 1O,OOO (Yerger 1978). Population levels
have certainly declined from levels prior to introduction of the brown
darter in the lower Rocky Bayou system, and most likely from habitat
degrading activities on Eglin Air Force Base.
HABITAT: Okaloosa darters inhabit cool to warm, small to moderate size
streams, 1.5 to 2O meters wide, in depths ranging 4 centimeters to 1.5
meters. Most streams are low gradient but with persistent discharge, and
drain sandhill terrain of managed mixed deciduous or coniferous forests.
These streams are sand-floored, slightly acidic, although usually not
dark stained, and open sunlit sections harbor a fairly diverse assemblage
of submergent and emergent macrophytes. The Okaloosa darter is typically
associated with cover, typically fine-stemmed macrophytes and detritus,
in or adjacent to moderate runs of less than 1 meter a second.
REASONS FOR CURRENT STATUS: The Okaloosa darter covers a limited range of
less than 248.8 occupied stream miles. Recently, some of this habitat has
been lost to the introduced and ecologically similar brown darter, E.
edwini. Habitat loss or degradation has also occurred from several other
factors including siltation, several small impoundments, and possibly
domestic pollution.
MANAGEMENT AND PROTECTION: The National Fisheries Research Center in
Gainesville, is currently conducting ecological studies of Okaloosa and
brown darters, concerning historical changes in distribution,
microhabitat overlap, and comparative reproductive biology; and is
working with the Fish and Wildlife Enhancement personnel and the Air
Force to identify limiting factors. Research will probably be completed
late Fiscal Year 1991 or early Fiscal Year 1992.
The principal recommendations of the Okaloosa darter recovery plan are as
follows: (1) determine biological characteristics and habitat
requirements (includes studies on distribution within the existing range,
habitat parameters, life history, population size, and hazards from such
factors as habitat modification and competition with the brown darter);
(2) protect extant populations and habitat (includes the identification
and evaluation of harmful activity, and reducing the effects of possible
competitors and predators); and, (3) increase population sizes and
reestablish range (includes habitat improvement and reestablishing the
range by transplanting experiments).
REFERENCES:
Collette, B.B., and R.W. Yerger. 1962. The American Percid Fishes of the
Subgenus Villora. Tulane Stud. Zool. 9:213-230.
Mettee, M.F., and E. Crittenden. 1979. A study of Etheostoma okaloosae
(Fowler) and E. edwini (Hubbs and Cannon) in Northwestern Florida,
1975-78. Rep. to U.S. Fish and Wild. Serv., Atlanta, GA.
Ogilvie, V.E. 1980. Endangered Wildlife Project. E-1, Study I-J: Okaloosa
darter investigation. Completion report, October 1, 1977-June 3O, 1980.
Fla. Fresh Water Fish Comm., Tallahassee.
**U.S. Fish and Wildlife Service. 1981. Recovery Plan for the Okaloosa
Dsrter (Etheostoma okaloosae). Prepared by the Okaloosa Darter Recovery
Team for U.S. Fish and Wildlife Service, Atlanta Georgia. 24 pp.
Yerger, R.W. 1978. Okaloosa Darter, pp. 2-4. In C.R. Gilbert (ed.). Rare
and endangered biota of Florida. Vol. 4, Fishes. Univ. Press. Fla.,
Gainesville.
For more information please contact:
U.S. Fish and Wildlife Service
31OO University Boulevard, South, Suite 12O
Jacksonville, Florida 32216
Telephone: 9O4/791-258O
The distribution of Etheostoma okaloosae (solid circles), localities
where E. okaloosae and E. edwini are sympatric (open circles), and
localities exclusively occupied by E. edwini (solid squares), based on
the most recent collection at each site.
Robert Rice
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