Lepomis microlophus

redear sunfish

Type Locality:

St. Johns River, Florida (Günther 1859 in: Eschmeyer 1990).

Etymology/Derivation of Scientific Name:

Lepomis, Greek, meaning “scaled gill cover”, microlophus, Greek, meaning “small nape” (Pflieger 1975).

Synonymy:

Pomotis microlophus: Gunther 1859:264 in: Eschmeyer 1990.

Eupomotis notatus: Forbes 1884:67.

Eupomotis heros: Large 1903:25; Forbes and Richardson 1908:259-260; O’Donnell 1935:487).

Lepomotis microlophus: Smith 1965:9.

Characters

Maximum size: 355 mm TL (Carlander 1977).

Life colors: Opercle margined with scarlet (normally faded in preserved material; Hubbs et al 1991). Back is iridescent olive green to brown, and sides below lateral line silvery to greenish brown with pale brown spots. Breast is white to yellow. Opercular spot black with a bright red-orange margin. Pectoral and pelvic fins are light; median fins are dusky. Young fish have irregular vertical bars along sides. Coloration of breeding males is very intense with an overall darker body color, so that ventral parts of head, breast, and pelvic fin appear black (Ross 2001).

Counts: Fewer than 55 lateral line scales; 3 anal spines (rarely 2 or 4); 6-13 dorsal fin spines; 6 or 7 branchiostegals (Hubbs et al 1991); 10-12 dorsal rays; 10-11 anal rays; 13-14 pectoral rays (Ross 2001).

Body shape: Relatively robust, somewhat elongate with pointed snout and small mouth (Ross 2001). Body depth usually contained two to two and one-half times in standard length (Hubbs et al 1991).

Mouth position: Terminal oblique (Goldstein and Simon 1999). No teeth on tongue or pterygoids (Hubbs et al 1991).

External morphology: Opercle stiff to its margin; gill rakers short, not reaching below base of second raker below when depressed; pectoral fins long and pointed, upper pectoral fin rays much longer than lower; pectoral fin contained 3.5 or fewer times in standard length; supramaxilla absent or shorter than breadth of maxilla; maxillary width less than suborbital; lateral line present (curved upward anteriorly; Ross 2002); scales ctenoid (Hubbs et al 1991).

Distribution (Native and Introduced)

U.S. distribution: Ranges throughout most of the southeastern United States (Hubbs et al. 1991). Native to peninsular Florida, lower Atlantic slope and Gulf slope drainages west to Texas, and north to southern Indiana (Lee 1980).

Texas distribution: Native to the eastern two-thirds of Texas from the Red River to the Rio Grande River; has been widely transplanted throughout the state (Hubbs et al. 1991). Warren et al. (2000) list the following drainage units for distribution of Lepomis microlophus in the state: Red River (from the mouth upstream to and including the Kiamichi River), Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River. Sparsely, but widely distributed throughout Little River drainage, Central Texas, with the exception of species absence in collections from the Blackland Prarie (Rose and Echelle 1981).

Abundance/Conservation status (Federal, State, NGO)

Populations in the southern United States are apparently secure (Warren 2000).

Habitat Associations

Macrohabitat: Found in large rivers, bayous, lakes (Carlander 1977).

Mesohabitat: Common in warm, clear, quiet water where vegetation, stumps, logs, and other cover abound; occasionally brackish water (12.3 ppt.) (Lee 1980). Species seems to be better adapted to brackish water than basses or other sunfishes, but at salinities above 4 ppt, individuals appear to be in poorer condition, perhaps due to the metabolic expense of maintaining proper water balance (Peterson 1991). In Louisiana study, turbidity not considered important factor to species habitat (Carlander 1977).

Biology

Spawning season: In Texas, season lasts from early May - early July (Schloemer 1947). Spawning occurs at water temperatures of 21-32 degrees C during the spring and early summer (Clugston 1966; Lee 1980). In Florida, spawning season may extend from March into August (Clugston 1966). Some evidence exists that peaks in spawning activity may correspond to times of full or new moons (Wilbur 1969).

Spawning location: Polyphils; miscellaneous substrate and material nesters that have adhesive eggs either attached or occur in clusters on any available substrate (Childers 1967; Hardy 1978; Simon 1999). Usually nesting in areas of water less than 3 feet deep, in colonies, on firm substrates, often in locations exposed to the sun (Childers 1967). Clugston (1966) reported community spawning, with nests located very close together at depths of 457-914 mm. Wilbur (1969) reported nests constructed over bottom types ranging from sand to soft mud, and nests constructed in areas containing aquatic plants.

Reproductive strategy: Guarders; nest spawners (Childers 1967; Simon 1999). Males produce grunt-like or popping sounds near the sides and around head of female during courtship (Gerald 1971). Males usually do not feed during the period that they are courting and defending the nest area (Wilbur 1969). Fry remain in nest about a week with male guarding (Carlander 1977).

Fecundity: Females reported to produce about 2,000 – 10,000 eggs; fertilized eggs range 1.3 – 1.6 mm in diameter; eggs hatch in 6 – 10 days (Carlander 1977).

Age at maturation: In Texas, individuals may spawn late in 1^st year of life (Carlander 1977). Normally matures by 2^nd year, although some studies indicate regional variation (Wilbur 1969; Lee 1980); Wilbur (1969) noted some individuals spawning within 1^st year of life.

Migration:

Longevity: Usually 5-6 years; fish may occasionally reach 9^th year (Carlander 1977).

Food habits: Trophic classifications and mode for this species: Invertivore, benthic and drift; crusher. Main food items are snails and small mussels, with aquatic insects taken also. Because of feeding mode, this species is known as the shell cracker in some parts of range (Goldstein and Simon 1999). Seldom feeds at surface; aquatic snails are major food item throughout range; diet also includes insect larvae and cladocerans (Carlander 1977, Lee 1980). Huish (1958) and Wilbur (1969) note this species feeding primarily on bottom-inhabiting organisms; common foods including mollusks (primarily small snails), midge larvae (chironomids), amphipods, and mayfly and dragonfly larvae. Individuals may swim head-down into the bottom, raising a cloud of sand or mud, when feeding on bottom-inhabiting prey such as mayflies or snails (Wilbur 1969). The feeding pattern of this species, crushing and consuming large numbers of snails, is unique among sunfishes found in Texas.  To accommodate feeding, both the bones of the pharyngeal jaws are enlarged, as are muscles responsible for the crushing movement. Species also shows a specialized pattern of muscle contraction that is not found in other, nonmolluskan-feeding sunfishes (Wainwright and Lauder 1992). Feeding involves acquiring a snail using the jaws, followed by the transfer of the snail to the pharyngeal area for crushing. After crushing shell, the soft tissues are held between upper chewing pad and pharyngeal teeth, remnants of the shell (about 85% of shell material) is then expelled (Stein et al. 1984). Major food items in Lake Ponchartrain, Louisiana, included mud crabs (Rhithropanopeus), other small crustaceans (especially gammarid amphipods) and midges. Midges more important in diet of small individuals; large large fish fed primarily on mud crabs (Desselle et al. 1978).

Growth: In Tennessee, L. microlophus average 109 mm TL in second summer, and 152, 175, 190, and 206 mm TL in succeeding summers; no significant difference in rate of growth between sexes (Schoffman 1939). Carlander (1977) noted average growth rates in the southeastern U.S.: 144 mm TL after one year, and 197 mm, 224 mm, and 226 mm at years 2-4, respectively.

Phylogeny and morphologically similar fishes

L. microlophus most similar to L. macrochirus (bluegill) and L. megalotis (longear sunfish); differs from L. macrochirus in lacking a distinct spot at the base of the soft dorsal fin and in having short and stubby versus long and slender gill rakers; species can be distinguished from L. megalotis by its long, pointed pectoral fin and by its very short ear flap. Although L. gulosus (warmouth) also have a red opercular spot, the combination of the red opercular spot and long pectoral fins differentiates L. microlophus from L. gulosus and other Lepomis (Ross 2001). Childers (1967) found the intergeneric centrarchid hybrid, L. microlophus X C. gulosus to be fertile.

Host Records

Trematoda, Cestoda, Nematoda, Acanthocephala (Arnold 1967).

Commercial or Environmental Importance

Lepomis microlophus reported to be good test animals, as individuals are easy to handle and not nervous (Carlander 1977). Ross (2001) noted that L. microlophus populations tend to decline in abundance in some lakes and ponds over time, perhaps due to competition for food and space with other sunfishes. Also, species may spawn only once during the summer, which puts them at a disadvantage, especially in bass-crowded situations.

References

Arnold, J. G., Jr. 1967. The Parasites of the fresh water fishes of Louisiana. Proceedings of the Twenty-First Annual Conference Southeastern Association of Game and Fish Commissioners, September 24-27, 1967. 1968:531-542.

Carlander, K. D. 1977. Handbook of Freshwater Fishery Biology. The Iowa State University Press, Ames 2:431.

Childers, W. F. 1967. Hybridization of Four Species of Sunfishes (Centrarchidae). Illinois Natural History Survey, Bulletin 29:159-214.

Clugston, J.P. 1966. Centrarchid spawning in the Florida Everglades. Quart. J. Fla. Acaad. Sci. 29(2):137-143.

Desselle, W.J., M.A. Poirrier, J.S. Rogers, and R.C. Cashner. 1978. A discriminant functions analysis of sunfish (Lepomis) food habits and feeding niche segregation in the Lake Pontchartrain, Louisiana estuary. Trans. Amer. Fish. Soc. 107(5):713-719.

Eschmeyer, W. N. 1990. Catalog of the genera of recent fishes. California Academy of Sciences, San Francisco.

Forbes, S. A. 1884. A catalogue of the native fishes of Illinois. Report of the Illinois State Fish Commissioner for 1884:60-89

Forbes, S. A. and R. E. Richardson. 1908. The fishes of Illinois. Illinois State Laboratory of Natural History cxxxi + 357 pp. + separate atlas containing 102 maps.

Gerald, J. W. 1971. Sound production during courtship in six species of sunfish (Centrarchidae). Evolution 25(1):75-87.

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.

Hardy, J.D. 1978. Development of fishes of the Mid-Atlantic Bight, an atlas of egg, larval, and juvenile stages, Vol. III. Aphredoderidae theough Rachycentridae. U.S. Fish Wildlife Service Biological Service Program. FWS/OBS-78/12.

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

Huish, M.T. 1958. Food habits of three Centrarchidae in Lake George, Florida. Proc. S.E. Assoc. Game Fish Comm. 11:293-302.

Large, T. 1903. A list of the native fishes of Illinois with keys. Appendix to Report of the State Board of Fish Commissioners for Sept. 30, 1900 to Oct. 1, 1902. 30pp.

Lee, D. S. 1980. Lepomis microlophus (Günther), Redear sunfish. pp. 601 in D. S. Lee, et al. Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

O'Donnell, J. 1935. Annotated list of the fishes of Illinois. Illinois Natural History Survey Bulletin 20(5): 473-500.

Peterson, M.S. 1991. Differential length-weight relations among centrarchids (Pisces: Centrarchidae) from tidal freshwater and oligohaline wetland habitats. Wetlands 11(2):325-332.

Rose, D. R. and A. A Echelle. 1981. Factor analysis of associations of fishes in Little River, Central Texas, with and interdrainage comparison. American Midland Naturalist 106(2):379-391.

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

Schloemer, C. L. 1947. Reproductive cycles of five species of Texas centrarchids. Science 106:85-86.

Schoffman, R. J. 1939. Age and growth of the red-eared sunfish in Reelfoot Lake. Jour. Tennessee Acad. Sci. 14(1):61-71.

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

Smith, P. Wayne. 1965. A preliminary annotated list of the lampreys and fishes of Illinois. Illinois Natural History Survey Biological Notes 54. 12p.Smith, Philip Wayne. 1979. The Fishes of Illinois. University of Illinois Press, Chicago 314 pp.

Stein, R.A., C.G. Goodman, and E.A. Marshall. 1984. Using time and energetic measures of cost in estimating prey value for fish predators. Ecology 65(3):702-715.

Wainwright, P. C. and G. V. Lauder. 1992. The evolution of feeding biology in sunfishes (Centrarchidae). Pages 472-491 in R. L. Mayden, ed. Systematics, Historical Ecology, and North American Freshwater Fishes. Stanford University Press, Stanford, California. xxvi + 969 pp.

Warren, L. W., 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.

Wilbur, R.L. 1969. The redear sunfish in Florida. Fish. Bull. Fla. Game Freshwater Fish Comm. 5:1-64.