spotted gar Lepisosteus oculatus

Lepisosteus oculatus

spotted gar

Type Locality

Duck Lake, Calhoun Co., MI, (Winchell 1864).

Etymology/Derivation of Scientific Name:

Lepisosteus, Greek, “bony scale;” oculatus, Latin meaning “provided with eyes,” in reference to the numerous roundish dark spots on the head and body (Pflieger 1997).

Synonymy

Lepisosteus oculatus Winchell 1864:183.

Lepisosteus productus Cook 1959:55.

Characters

Maximum size: 1092 mm TL (Lambou 1961b).

Coloration: Back and upper sides olive, grading to whitish below, with numerous dark oval spots on head, body, fins. Suttkus (1963) noted fish from more heavily stained water from pinelands and cypress swamps tended to be darker, some having the ventral surface dark. Young gar have a brown lateral band extending from snout to upper lobe of caudal fin, upper side of the band generally even anteriorly, becoming more irregular from midbody posteriorly. Lower edge of band darker, bounded by distinct white band.Undersides of body have numerous small black spots on white background. Upper lobe of caudal fin yellow-brown and lower lobe has irregular black bars medially. Edge of caudal fin black; middorsal band brown; dorsal, anal, pelvic fins have irregular brown bars; each pectoral fin has brown spot at base, becoming clear distally (Ross 2001).

Counts: 54-57 lateral line scales; 46-49 predorsal scales; 32-38 scale rows around body (Hubbs et al. 1991); 15-24 pear shaped gill rakers; 6-9 dorsal rays; 7-9 anal rays (Ross 2001).

Body shape: Moderately sized gar (Ross 2001). Beak short and blunt, its least width about five to seven times its length; snout less than two-thirds of head length; large teeth in upper jaw in one row on each side (Hubbs et al. 1991).

Mouth position: Terminal (Goldstein and Simon 1999).

External morphology:

Distribution (Native and Introduced)

U.S. distribution: Occurs from Lake Erie southeastward through the Ohio and Missouri drainages of the Mississippi, then westward through the coastal streams of Texas (Hubbs et al 1991).

Texas distribution: Warren et al. (2000) list the following drainage units for species distribution in the state: Red River unit, Sabine Lake unit (including minor coastal drainages up to and including the Kiamichi River), 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.

Abundance/Conservation status (Federal, State, NGO)

Populations in the southern drainages are currently stable (Warren et al. 2000).

Habitat Associations

Macrohabitat: Most abundant in clear, quiet waters with much aquatic vegetation; enters brackish water along Gulf Coast (Lee and Wiley 1980). In the Brazos River, Texas, found in the river channel and, on occasion, Brazos River oxbow lakes (Winemiller et al. 2004).

Mesohabitat: In Lake Texoma, Oklahoma, young-of-year inhabited densely weeded areas; largely inactive during the day; actively swam in open waters at night. Adults were in deeper water during the day, moving into shallow areas at night (Echelle and Riggs 1972). May be less tolerant of turbidity than other gar and tend to be more associated with aquatic vegetation (Lee and Wiley 1980; Pfliger 1997; Ross 2001).

Biology

Spawning season: In Lake Texoma, Oklahoma spawning in spring (April), in quiet, weedy backwaters over dead vegetation and algal mats (Echelle and Riggs 1972); in Lake Lawtonka, OK, mid-April to early June (spawning interrupted by advent of cooler temperatures and turbid water resulting from spring rain; Tyler and Granger 1984); in southeastern Missouri, spawning observed in late April (Redmond 1964); in Louisiana, February - June (Love 2004).

Spawning habitat: Nonguarder; open substratum spawner; phytophil: obligatory plant spawners with adhesive egg envelopes that stick to submerged live or dead plants. Free embryos hatch late and possess cement glands. Larvae also possess extremely well-developed embryonic respiratory structures and have no photophobic reaction (Balon 1981; Simon 1999). Spawning in shallow water among rooted aquatic vegetation (Lee and Wiley 1980; Tyler and Granger 1984; Love 2004). In Mingo Swamp, southeastern Missouri, spawning observed in rapidly-flowing water coming from a tract of flooded timber (Redmond 1964).

Spawning Behavior: In southwestern Oklahoma, Tyler and Granger (1984) observed typical behavior: a large female, closely accompanied by 3-5 much smaller males, would swim slowly through well-vegetated shallows; apparent moment of egg deposition denoted by quick jerks, thrashing and concomitant splashing of female.

Fecundity: In Louisiana, fecundity highest during October (mean number of eggs = 13, 798 ± 7,654 SE), lowest during June (mean number of eggs = 1,772 ± 392 SE); ova diameters varied among months and among individuals within a month; mean ova diameter during spawning season (February-June) was 3.02 mm ± 0.02 SE; a female can release over 5,000 ova during the spawning season, but number likely varies with body size (Love 2004). Recently hatched young are typical of young Lepisosteus generally, with a well-developed adhesive organ on the snout and a large ovoid yolk sac (Simon and Tyberghein 1991).

Age at maturation: In Louisiana, before age 2; fishes older than 1 were mature (males 305-383 mm and females 412-478 mm; Love 2004); in Missouri, males mature at 2-3 years old; females during 3^rd or 4^th year (Redmond 1964).

Migration:

Growth and Population Structure: Males grew faster than females in a Louisiana study: males averaged 278 mm after the first year, then an average of 48-33 mm/year during the first four years, then less than 15.82 mm/year for remaining years; females averaged 299 mm after the first year, then an average of 38.07 mm/year, then 30.50 mm/year for remaining years. Sex ratios were near 1:1 for ages 1-7, but females more common than males for ages 8-10 (1 male and 7 females); condition generally lowest during fall, varied by sex during seasons (Love 2004). In southeastern Missouri, species reaches a length of about 254 mm at end of first year of life, and is about 508 mm long at 3 years old. Males grow faster than females for the first 2 years, but thereafter females grow more rapidly and attain the largest size (Redmond 1964). Larval development: yolk-sac larvae 7-8 mm TL at hatching, with adhesive disk on snout; by 16-17 mm TL, there are 44-47 preanal, 12-15 postanal, 58-59 total myomeres; median fin fold still continuous, pectoral fin is rounded but without apparent rays; yolk sac absorbed by about 17 mm TL (Simon and Wallus 1990). Pope and Wilde (2003) studied variation in Lepisosteus oculatus mass-length relationships in Texas reservoirs: total length and mass measured on 883 spotted gar collected between 1984 and 1996 from 49 reservoirs; mass was positively related to length; mass-length relationships differed significantly among reservoirs.

Longevity: In a Louisiana study, males lived up to 8 years, and females up to 10 years (Love 2004). In a southeastern Missouri study, an 18 year old female was oldest fish found (Redmond 1964).

Food habits: Trophic classifications, mode, and feeding behavior follow: carnivore; whole body (piscivore); ambush; voracious piscivore (Goldstein and Simon 1999). In inland habitats, small L. oculatus (15-114 mm TL) feed on crustaceans (Cladocera), insects, and fishes, switching to mostly fish at larger sizes (115-306 mm TL); in Lake Texoma, diet composition which includes inland silverside and shad suggests primarily surface oriented feeding (Echelle and Riggs 1972). In Texas, Bonham (1941) reported crayfish and gizzard shad (Dorosoma cepedianum) were most important food items, followed by small sunfish and minnows (length not exceeding 40 mm); freshwater shrimp (Palaemonetes exilipes) is also a common item of diet. In southeastern Missouri, mosquito larvae and small crustaceans are first food of young L. oculatus, with fish appearing in diet at an early age and thereafter becoming the main food; mosquitofish and topminnows being the principal species taken by young gar; 90% of adult diet consists of fishes, mostly gizzard shad, and the remaining 10% includes freshwater shrimp, crayfish, and insects (Redmond 1964). In Lake Ponchartrain area of Louisiana, 93% of gar from one locality had consumed fishes, commonly sheepshead minnows, sailfin mollies, and mosquitofishes; various sunfishes may also be common food item. L. oculatus collected from another site fed mostly (61% of gar) on arthropods, including blue crabs; fishes such as inland silversides and gulf menhaden important food item. Plant material was common in diet, but may have been incidental while feeding on fishes (Lambou 1961a; Knight and Hastings 1987). In tidewater areas, diet includes numerous blue crabs (Callinectes sapidus) and fishes, depending upon the habitat. In coastal areas of Mississippi, small fiddler crabs (Uca pugnax) are dominant prey in shallow bayous, while small blue crabs are primary prey in open water; gulf menhaden most abundant fish consumed. Fishes may be more important food item at night, rather than during daylight hours; feeding intensifies during rising or high tides (Goodyear 1967; Ross 2001).

Phylogeny and morphologically similar fishes

Lepisosteus oculatus most closely resembles L. platostomus in snout shape but usually has more spotting on fins and body, though spotting less evident on specimens from turbid water. Also, L. oculatus has 54-58 (versus usually 60-63) lateral scale rows and usually 47-50 (versus 52-53) predorsal scales. L. oculatus differs from L. osseus in having a relatively shorter and much broadrer snout. Larvae have 45-49 preanal myomeres versus 37-45 in L. osseus and L. platostomus (Boschung and Mayden 2004).

Host Records

Cestoda (1); Acanthocephala (Texas) (1) (Mayberry et al., 2000).

Commercial or Environmental Importance

Generally not sought by anglers; however, flesh is palatable. Eggs are toxic and should not be eaten (Ross 2001).

[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Big Sandy Creek (Evans and Noble 1979); Hillebrandt Bayou (Linam and Kleinsasser 1987a); Oyster Creek (Linam and Kleinsasser 1987b); Allens Creek and the Brazos River (Austin Co.; Linam et al.1994); San Antonio River and Guadalupe River (Edwards 1999); Pinto Creek (Edwards 2003).]

References

Balon, E.K. 1981. Additions and amendments to the classification of reproductive styles in fishes. Environmental Biology of Fishes 6:377-389.

Bonham, K. 1941. Food of gars in Texas. Transactions of the American Fisheries Society 70(1):356-362.

Boschung, H.T., Jr., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Books, Washington. 736 pp.

Cook. F. A. 1959. Freshwater fishes in Mississippi. Mississippi Game and Fish Commission, Jackson.

Echelle, A. A., and C. D. Riggs. 1972. Aspects of the early life history or gars (Lepisosteus) in Lake Texoma. Trans. Amer. Fish. Soc. 101(1):106-112.

Edwards, R.J. 1999. Ecological profiles for selected stream-dwelling Texas freshwater fishes II. Report to the Texas Water Development Board. 69 pp.

Edwards, R.J. 2003. Ecological profiles for selected stream-dwelling Texas freshwater fishes IV. Report to the Texas Water Development Board. 19 pp.

Evans, J.W., and R.L. Noble. 1979. The longitudinal distribution of fishes in an East Texas stream. American Midland Naturalist 101(2):333-343.

Goodyear, C. P. 1967. Feeding habits of three species of gars, Lepisosteus, along the Mississippi Gulf Coast. Trans. Amer. Fish. Soc. 96(3):297-300.

Goldstein, R.M., and T.P. Simon. 1999. Toward a united definition of guild structure for feeding ecology of North American freshwater fishes. pp. 123-202 in T.P. Simon, editor. Assessing the sustainability and biological integrity of water resources using fish communities. CRC Press, Boca Raton, Florida.

Hubbs, C., R. J. Edwards, and G. P. Garrett. 1991. AN annotated checklist of the freshwater fishes of Texas, with keys to identification of species. The Texas Journal of Science, Supplement, 43(4):1-56

Knight, C. L., and R. W. Hastings. 1987. A comparison of the food habits of spotted gar (Lepisosteus oculatus) from two habitats in the Lake Pontchartrain drainage system. Proc. La. Acad. Sci. 50:27-31.

Lambou, V. W. 1961a. Utilization of macrocrustaceans for food by freshwater fishes in Louisiana and its effects on the determination of predator-prey relations. Prog. Fish-Cult. 23(1):18-25.

Lambou, V.W. 1961b. Efficiency and selectivity of flag gillnets in Lake Bistineau, Louisiana. Proc. S.E. Assoc. Game Fish Comm. 15:319-359.

Lee, D. S., and E.O. Wiley. 1980. Lepisosteus oculatus (Winchell), Spotted gar. pp. 48 in D. S. Lee, et al. Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

Linam, G.W., and L.J. Kleinsasser. 1987a. Fisheries use attainability study for Hillebrandt Bayou. River Studies Report No. 1. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 18 pp.

Linam, G.W., and L.J. Kleinsasser. 1987b. Fisheries use attainability study for Oyster Creek (Segment 1110). River Studies Report No. 3. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 15 pp.

Linam, G.W., J.C. Henson, and M.A. Webb. 1994. A fisheries inventory and assessment of Allens Creek and the Brazos River, Austin Count, Texas. River Studies Report No. 12, Texas Parks and Wildlife Department, Austin. 13 pp.

Love, J. W. 2004. Age, growth, and reproduction of spotted gar, Lepisosteus oculatus (Lepisosteidae), from the Lake Ponchertrain estuary, Louisiana. Southwestern Naturalist 49(1):18-23.

Mayberry, L. F., A. G. Canaris, and J. R. Bristol. 2000. Bibliography of parasites and vertebrate host in Arizona, New Mexico, and Texas (1893-1984). University of Nebraska Harold W. Manter Laboratory of Parasitology Web Server pp. 1-100.

Page, L. M., and B. M. Burr. 1991. A Field Guide to Freshwater Fishes of North America, north of Mexico. Houghton Mifflin Company, Boston, 432 pp.

Pflieger, W. L. 1997. The Fishes of Missouri. Missouri Department of Conservation, Jefferson City, 372 pp.

Pope, K.L., and G.R. Wilde. 2003. Variation in spotted gar (Lepisosteus oculatus) mass-length relationships in Texas reservoirs. The Texas Journal of Science 55(1):43-48.

Redmond, L.C. 1964. Ecology of the spotted gar (Lepisosteus oculatus Winchell) in southeastern Missouri. M.A. Thesis, Univ. Missouri, Columbia. 144pp.

Ross, S. T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson. 624 pp.

Simon, T. P. 1999. Assessment of Balon’s reproductive guilds with application to Midwestern North American Freshwater Fishes, pp. 97-121. In: Simon, T.L. (ed.). Assessing the sustainability and biological integrity of water resources using fish communities. CRC Press. Boca Raton, Florida. 671 pp.

Simon, T.P., and R. Wallus. 1990. Family Lepisosteidae, pp. 59-86. In: Reproductive Biology and Early Life History of Fishes in the Ohio River Drainage. R. Wallus, T.P. Simon, and B.L. Yeager, eds. Vol. I: Acipenseridae through Esocidae. Tennessee Valley Authority, Chattanooga, TN.

Simon, T.P., and E.J. Tyberghein. 1991. Contributions to the early life history of the spotted gar, Lepisosteus oculatus Winchell, from Hatchet Creek, Alabama. Trans. Ky. Acad. Sci. 52(3/4):124-131.

Suttkus, R.D. 1963. Order Lepisostei, pp. 61-88, In: H.B. Bigelow and W.C. Schroder, eds. Fishes of the Western North Atlantic. Memoirs Sears Found. Mar. Res. I, Pt. 3. New Haven, CT.

Tyler, J.D., and M.N. Granger. 1984. Notes on food habits, size, and spawning behavior of spotted gar in Lake Lawtonka, Oklahoma. Proc. Okla. Acad. Sci. 64:8-10.

Warren, M.L. Jr., B.M. Burr, S. J. Walsh, H.L. Bart Jr., R. C. Cashner, D.A. Etnier, B. J. Freeman, B.R. Kuhajda, R.L. Mayden, H. W. Robison, S.T. Ross, and W. C. Starnes. 2000. Diversity, distribution and conservation status of the native freshwater fishes of the southern United States. Fisheries 25(10):7-29.

Winchell, A. 1864. Description of gar-pike, supposed to be new - Lepidosteus (Cylindrosteus) oculatus. Proc. Acad. Net. Sci. Phil. 16:183-185.

Winemiller, K.O., F.P. Gelwick, T. Bonner, S.C. Zeug, and C. Williams. 2004. Response of Oxbow Lake Biota to Hydrologic Exchanges with the Brazos River Channel. Report to the Texas Water Development Board. 59 pp.