Lepisosteus osseus
longnose gar
Type Locality
Virginia (Linnaeus 1758).
Etymology/Derivation of Scientific Name
Lepisosteus, Greek,
“bony scale;” osseus, Latin, meaning “of bone” (Pflieger 1997).
Synonymy
Esox osseus Linnaeus
1758
Characters
Maximum size: The
angler record, fish recorded at 1,830 mm (72 in), 22.7 kg (50 lb) from the Trinity River,
Texas, 30 July 1954 (Walden 1964; Page and Burr 1991).
Coloration: Adult
olive to dark green above; whitish below with large round spots on dorsal,
anal, and caudal fins. Young distinctly marked with broad brown or blackish
mid-lateral stripe from snout to base of caudal fin, with a prominent white
stripe immediately below, and chocolate brown stripe on each side of belly
(Becker 1983).
Counts: 57-65 lateral
scales; 47-55 predorsal scale rows; 17-24 transverse scale rows; 14-31 gill
rakers (Etnier and Starnes 1993).
Body shape: Long and
cylindrical.
Mouth position:
Terminal (Goldstein and Simon 1999).
Morphology:
Scales ganoid; tail abbreviate-heterocercal (vertebrae moving
into dorsal portion of fin); gill rakers rudimentary, irregularly arranged
(Becker 1983). Large canine teeth in one row on each side of upper jaw
(Hubbs et al. 1991,
2008).
Snout long
and narrow, its least width goes about 12 to 20 times in snout length; snout more
than two-thirds of head length (Hubbs et al. 1991, 2008).
Distribution (Native and Introduced)
U.S. distribution:
Found from Quebec through out the eastern United States southward to the Rio
Grande drainage in Texas, Mexico and New Mexico (Hubbs et al. 1991, 2008).
Texas distribution:
May be found in most Texas Rivers (Hubbs et al. 1991, 2008). Warren et al.
(2000) list the following drainage units for species distribution in the
state: Red River unit (from the mouth upstream to and including the Kiamchi
River), Sabine Lake unit (including minor coastal drainages west to
Galveston Bay), Galveston Bay unit (including minor coastal drainages west
to mouth of Brazos River), Brazos River unit, Colorado River unit, San
Antonio Bay unit (including minor coastal drainages west of mouth of
Colorado River to mouth of Nueces River), Nueces River unit.
[Additional literature
noting collection of this species from Texas locations includes, but is not
limited to the following: Lower Rio Grande (Robinson 1959); Brazos River
(Linam et al. 1994).]
Abundance/Conservation status (Federal, State,
Non-governmental organizations)
Populations in southern
drainages are Currently Stable (Warren et al. 2000).
Habitat Associations
Macrohabitat: Larger
streams and coastal inlets throughout range; occasionally found in marine
coastal waters (Wiley 1980); occurs in large rivers, reservoirs, swamps and
oxbow lakes, and may be expected in small rivers during spawning season
(Etnier and Starnes 1993).
Mesohabitat: Fresh and
brackish waters (Wiley 1980). Young gar reside in shallow water, moving
to deeper water as they grow larger and perhaps becoming more nocturnal
(Haase 1969). During daylight hours, most time spent
near submerged or overhanging objects close to shore (Echelle and Riggs
1972). At night, commonly found swimming actively in shallow, open waters.
This species shows a preference for high water temperatures and has been
found in water as warm as 33.9°C, 93°F (Becker 1983). In Texas, they are
commonly found in the Brazos River though they are rare in oxbow lakes.
However, they may periodically dominate oxbows that connect to the active
channel, this
occurs when gar enter oxbows during floods to forage and then return to the river as water levels fall (Winemiller
et al. 2004).
Biology
Spawning season: In
the spring; typically when water temperature is between 17.8 to 21.1°C,
64-70°F
(Dean 1895; Netsch and Witt 1962). Breeding may
occur as late as August, depending on
geographic location (Carlander 1969; Wiley 1980).
Spawning Habitat:
Nonguarders; open substratum spawners; phytolithophils: nonobligatory
plant spawner that deposit eggs on submerged items, have hatching
larvae with cement glands in free embryos, have larvae with moderately
developed respiratory structures, and have larvae that are photophobic
(Simon 1999; Balon 1981). In Wisconsin, spawning occurred on a shallow
gravel bar in water 0.3-0.9 m (1-3 ft) deep, with bulrushes were present; spawning also
occurred in water 2 m (6.6 ft) deep over a substrate of boulders (Haase 1969). Spawning
occurs in gravel shoal areas and among rocks (Dean 1895; Yeager and Bryant
1983); also in the weedy shallows of lakes and rivers (Echelle and Riggs
1972). It has been found that interspecific nest utilization occurs, as
longnose gar have been found to deposit their eggs into smallmouth bass
nests, presumably to exploit the brood care afforded by the
smallmouth bass (Goff 1984).
Spawning behavior:
After a period of circling in shallow water with several males females
release eggs in repeated batches which are fertilized by the trailing
male(s). Longnose gar do not display parental care of eggs or larvae (Dean 1895; Goff 1984).
Fecundity: Multiple
clutch spawners (Goff 1984). Depending on size of female, from 1,110-77,156
eggs laid; eggs are green and range from 2.1-5.5 mm (.08-.22 in) in diameter; incubation
period 7-9 days, varying with water temperature; emerging sac-fry will
attach to submerged objects by adhesive yolk structure, remaining inactive
until yolk sac is absorbed (Haase 1969; Echelle and Riggs 1972, Sublette et
al. 1990). Yeager and Bryant (1983) reported that eggs hatched in 3 days at
26°C (79°F).
Age at maturation:
Males mature at 3-4 years, females at 6 years (Netsch and Witt 1962).
Migration: Have been
known to move inshore to shallow water or upstream to spawn in pools as far
as 10 km (6.2 mi). Instream residence has been recorded from 15-94 days, with males
having longer residence times than females (Yeager and Bryant 1983; Johnson
and Noltie 1996).
Growth and Population
Structure: Growth rapid during first year of life: In aquariums, Echelle
and Riggs (1972) noted average growth of 3.2 mm/day (0.13 in/day); in Michigan, Hubbs
(1921) reported estimated daily growth of 2.33 mm (0.09 in); in Wisconsin, Haase
(1969) reported growth of 1.5 mm/day (.06 in/day). In Wisconsin, young-of-year reached a
maximum of 460 mm (18 in) TL and one-half of maximum growth in length was attained
during the first 2-3 years of life (Haase 1969). In central Missouri, Netsch
and Witt (1962) determined age and growth from branchiostegal rays: Age-1
males were 495 mm (19.5 in) long, females were 559 mm (22 in); females continue to grow
approximately 25 mm/year (0.98 in/year) for 13-14 years; females average 64 mm
(2.5 in) longer than
males, at the end of the first year; disparity in size increases with age to
a point where females are 178 mm (7 in) longer than males at the end of 11th
year of life. Yeager and Bryant (1983) reported larvae 8.8-9.9 mm (0.35-0.39)
in length at
hatching.
Longevity: Haase
(1969) recorded a 32-year-old female from Lake Mendota, Wisconsin, and
reported males up to 27 years old from the same location. Females outlive
males (Netsch and Witt 1962).
Food habits: Trophic
classifications and mode: carnivore; whole body (piscivore); ambush
(Goldstein and Simon 1999). In Texas, the diet of longnose gar
specimens collected included sunfishes, catfish, crayfish, mullets,
and specifically gray redhorse, and
gizzard shad (Bonham 1941). Main food
items are various species of spiny and soft rayed fishes (Haase
1969; Cahn 1927; Goldstein and Simon 1999).
In Mississippi coastal waters, heavy predation on menhaden was reported
(Goodyear 1967). Young to 50 mm (2 in) TL
feed upon
invertebrates. Brackish-water individuals are reported to also eat crabs
(Carlander 1969; Wiley 1980).
Phylogeny and morphologically similar fishes
Lepisosteus osseus specimens larger than 6 inches are not likely
to be confused with L. platostomus (shortnose gar) and L.
octulatus (spotted gar); L. osseus can be distinguished from the
latter two species by the extremely long snout (versus much shorter, wider
snouts; Hubbs et al. 1991; Page and Burr 1991; Etnier and Starnes 1993).
Smaller juveniles of these three gar species have similar color
patterns, but Suttkus (1963) indicated that
the dark mid-lateral band of L. osseus is scalloped on its dorsal margin
(straight in L. oculatus) and the mid-dorsal stripe is cinnamon
colored and narrow (broader and darker in L. oculatus; Etnier and
Starnes 1993).
Hybridization between L.
osseus and Atractosteus spatula (alligator gar) has been reported
(Gilbert 1992). Herrington et al. (2008) provided conclusive evidence of
intergeneric hybridization in L. osseus and A. spatula, and
described hybrid specimens spawned in an aquarium: body coloration and
transverse scale row counts were similar to those of longnose gar; snout length
and shape intermediate between those of longnose and alligator gar; two
rows of teeth on the upper jaw as seen in alligator gar.
Host Records
Trematoda
(2); Cestoda (1); Nematoda (3); Acanthocephala; Crustacea (Hoffman 1967;
Mayberry 2000).
Commercial or Environmental Importance
No
information at this time.
References
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