Picture by Chad Thomas, Texas State University-San Marcos
Delaware and Chesapeake bays (Lesueur 1818).
Etymology/Derivation of Scientific Name
Doro, meaning “lanceolate”; soma, meaning “body,” in reference to the body shape of the young; cepedianum, in honor of Bernard Germain Etienne de la Ville sur Ilion, Comte de La Cepede (1756-1825) who, during the French Revolution, was known as Citoyen Lacepede; it was during this time, amidst unfavorable conditions, that Lacepede authored Histoire Naturelle des Poissons (Scharph 2005).
Megalops cepediana Lesueur 1818:361.
Dorosoma cepedianum Hay 1881:502, 1883:67; Hildebrand and Towers 1928:114; Miller 1950:405, 1960:373; Cook 1959:67.
Maximum size: 521 mm (20.5 in) TL (Miller 1960).
Coloration: Dorsal region blue-green with 6-8 dark, horizontal stripes; lateral region silver-white with black shoulder spot; ventral region silver-white.
Counts: Anal fin soft rays 29-33 (Hubbs et al 1991); lateral scales 59-67; midline of belly with 17-19 sharp scutes in front of pelvic fins and 10-12 behind (Miller and Robison 2004); dorsal fin soft rays 10-13 (Robison and Buchanan 1988).
Body shape: Deep body, laterally compressed.
Mouth position: Subterminal mouth.
Morphology: Blunt snout, adipose eyelid; axillary scale at base of pelvic fins; last ray of dorsal fin greatly elongated; ventral scales form a serrated edge. Gill rakers long and comblike (Miller and Robison 2004). Teeth present only on young fish; gizzard; long gut with numerous pyloric caeca; (Goldstein and Simon 1999).
Distribution (Native and Introduced)
U.S. distribution: Eastern part of US from Great Lakes to Mexico. Widely introduced.
Texas distribution: Statewide; can be highly abundant in reservoirs, often constituting over half of the fish biomass (Hubbs et al. 1991). Warren et al. (2000) listed the following drainage units for distribution of gizzard shad 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.
[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Baughman (1946); Edwards and Contreras-Balderas (1991); Linam and Kleinsasser (1996); Gelwick et al. (2001).]
Abundance/Conservation status (Federal, State, Non-governmental organizations)
Currently stable in southern United States (Warren et al. 2000).
Macrohabitat: Natural inland lakes, ponds, and pools and backwaters of low gradient streams (Megrey 1980); reservoirs (Hubbs et al. 1991).
Mesohabitat: Species prefers warm water with high phytoplankton production; occupies littoral and limnetic regions in lakes and reservoirs. Commonly enters brackish water and occasionally marine waters (Megrey 1980). This species tolerates water temperatures as high as 35°C, 95° F (Miller 1960). Along the Texas coast, species found at salinities up to 33.7 ppt (Gunter 1945). As turbidity increases, larval shad will concentrate near the surface (Matthews 1984). Bodola (1966) noted that very young shad were found in mid-summer close to shore, usually in shallow water; shad older than age-group III were rarely found in shallow water; the preference for deeper water seemed to increase with age. Riggs and Bonn (1959) reported that gizzard shad were the most abundant species in Lake Texoma, Oklahoma and Texas, and its tail waters; juveniles and adults were commonly taken throughout the lake down to a depth of 40 feet, and large schools of young-of-year occurred frequently in shallow water or ranging through most parts of lake near the surface.
Spawning season: In fresh water, spawning occurs with rising water temperature, from April through June (Bodola 1966; Baglin and Kilambi 1968; Megrey 1980). In western Lake Erie, heaviest spawning occurred at water temperatures of 19.4°C (66.9° F) or greater (Bodola 1966).
Spawning Habitat: Nonguarders; open substratum spawners. Freshwater lithopelagophils; rock and gravel spawners with free pelagic embryos (Bodola 1966; Simon 1999). Bodola (1966) reported spawning on a bar in shallow water, with a substrate of sand, gravel, and boulders; eggs sink slowly after they are spawned, the capsules adhering to surfaces such as submerged aquatic plants and gravel upon contact.
Spawning behavior: Most spawning occurred during the evening and night; not all mature eggs are expelled at the same time, but female may spawn on more than one occasion (Bodola 1966). Schools of male and female shad swim near the surface, rolling and tumbling about each other; eggs and milt are released during the process (Miller 1960).
Fecundity: Depending upon size and age, females from Beaver and Bull Shoals reservoirs, Arkansas, contained about 20,000-170,000 mature ova (Kilambi and Baglin 1969). Range between 22,400 - 543,910 oocytes per fish measuring between 225-363 mm (8.86-14.3) SL; fish of 282-285 mm (11.1-11.2) SL had highest fecundity values (Bodola 1966). In Mississippi, Hildebrand and Towers (1928) reported collection, during the month of June, of a ripe female measuring 315 mm (12.4) in length and containing about 50,000 eggs. Hatching occurs in 95 hours at 16.1°C (61.0°F), or 36 hours at 26.7°C, 80.1°F (Bodola 1966; Robison and Buchanan 1988)
Age at maturation: Age 1 for a few; most by age 2; rarely at age 3 (Bodola 1966).
Migration: When ready to spawn, females migrated from deeper water to inshore spawning sites, returning to deeper water after spawning; males also migrated to the spawning sites (where they were 2-3 times as numerous as females;
Growth and Population structure: In western Lake Erie, Bodola (1966) reported an abundance of age-groups 0, I, and II in samples, while age-group III was significantly less well represented, and older fish extremely scarce; seasonal growth was most rapid in July-August, and much reduced or absent January-April; males reached average standard lengths of 141 mm (5.55 in), 273 mm (10.7 in), 313 mm (12.3 in), 343 mm (13.5 in), and 349 mm (13.7 in), at the end of years 1-5, respectively; females attained standard lengths of 140 mm (5.51 in), 285 mm (11.2 in), 335 mm (13.2 in), 364 mm (14.3 in), and 386 mm (15.2 in), at the end of years 1-5, respectively. In Indiana, average standard lengths were 72 mm (2.83 in), 193 mm (7.60 in), 246 mm (9.69 in), 267 mm (10.5 in), 287 mm (11.3 in), and 325 mm (12.8 in) at the end of years 1-5, respectively. (Lagler and Applegate 1942).
Longevity: Up to 6 years (Kilambi and Baglin 1969).
Food habits: Goldstein and Simon (1999) list first and second level trophic classifications as herbivore and filter feeder, respectively. Completely herbivorous filter feeders (Whitehead 1985; Goldstein and Simon 1999). Juveniles feed on plankton (Goldstein and Simon 1999); adults consume zooplankton, microcrustaceans, phytoplankton, and detritus (Megrey 1980). Adults use hundreds of long, thin gill rakers to remove particulate matter from the water (Bodola 1966); adult fish also graze over the bottom ingesting detritus, sand and bottom ooze (Baker et al.1971).
Phylogeny and morphologically similar fishes
Closely related to Dorosoma petenense (threadfin shad), which has a terminal mouth, 42-48 lateral line scales, a shorter anal fin (20-27 rays), and fewer than 17 ventral scutes before the pelvic fins; the caudal fin and back are also more yellowish than in D. cepedianum (Miller and Robison 2004). Characteristics which differentiate D. cepedianum and D. petenense larvae: in fish ranging from 3-5 mm TL, D. cepedianum lack eye pigmentation, but the eye is pigmented in D. petenense; in fish ranging from 6-20 mm TL, D. cepedianum specimens have 46-54 total myomeres, while D. petenense specimens have 40-46 total myomeres; D. cepedianum sized >22 mm TL have 29-35 anal fin rays, while D. petenense sized >22 mm TL have 17-27 anal fin rays (Santucci and Heidinger 1986). Species hybridizes with D. petenense (Minckley and Krumholz 1960). D. cepedianum is superficially similar to Hiodon alosoides (goldeye), Alosa chrysochloris (skipjack herring), and Brevoortia patronus (Gulf menhaden) but differs in having an elongate last dorsal ray and median predorsal area naked and not crossed by scales (Boschung and Mayden 2004).
Trematoda, Acanthocephala (Mayberry et al. 2000).
Commercial or Environmental Importance
Used as a forage fish in reservoirs, likely inhibits production of game fishes by interspecific competition when overabundant (Megrey 1980).
Baglin, R.E., and R.V. Kilambi. 1968. Maturity and spawning periodicity of the gizzard shad, Dorosoma cepedianum (Lesueur), in Beaver Reservoir. Proc. Ark. Acad. Sci. 22:38-43.
Baker, C.D., D.W. Martin, and E.H. Schmitz. 1971. Separation of taxonomically identifiable organisms and detritus taken from shad foregut contents using density-gradient centrifugation. Trans. Amer. Fish. Soc. 100(1):138-139.
Baughman, J.L. 1946. An interesting association of fishes. Copeia 1946(4):263.
Bodola, A. 1966. Life history of the gizzard shad, Dorosoma cepedianum (Lesueur), in western Lake Erie. Fishery Bulletin of the U.S. Fish and Wildlife Service 65(2):391-425.
Boschung, H.T., Jr., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Books, Washington, D.C. 736 pp.
Cook, F.A. 1959. Freshwater fishes in Mississippi. Mississippi Game and Fish Commission, Jackson.
Edwards, R.J., and S. Contreras-Balderas. 1991. Historical changes in the icthyoffauna of the lower Rio Grande (Rio Bravo del Norte), Texas and Mexico. The Southwestern Naturalist 36(2):201-212.
Gelwick, F.P., S. Akin, D.A. Arrington, and K.O. Winemiller. 2001. Fish assemblage structure in relation to environmental variation in a Texas Gulf Coastal wetland. Estuaires 24(2):285-296.
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. 671 pp.
Gunter, G. 1945. Studies on marine fishes of Texas. Publ. Inst. Mar. Sci. Univ. Tex. 1(1):1-190.
Hay, O.P. 1881. On a collection of fishes from eastern Mississippi. Proc. U.S. Nat. Mus. 3:488-515.
Hay, O.P. 1883. On a collection of fishes from lower Mississippi valley. Proc. Bull. U.S. Fish Comm. 2:57-75.
Hildebrand, S.F., and I.L. Towers. 1928. Annotated list of fishes collected in the vicinity of Greenwood, Mississippi, with descriptions of three new species. Bulletin of the Bureau of Fisheries 43(2):105-136.
Hubbs, C., E.J. Roberts, 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.
Kilambi, R.V., and R.E. Baglin. 1969. Fecundity of the gizzard shad, Dorosoma cepedianum (Lesueur), in Beaver and Bull Shoals reservoirs. American Midland Naturalist 82(2):444-449.
Lagler, K.F., and V.C. Applegate. 1942. Age and growth of the gizzard shad, Dorosoma cepedianum (Lesueur), with a discussion of its value as a buffer and as forage of game fishes. Invest. Ind. Lakes and Streams 2:99-110.
Lesueur, C.A.1818. Descriptions of several new species of North American fishes. J. Acad. Nat. Sci. Phil. 1(2):222-235, 359-368.
Linam, G.W., and L.J. Kleinsasser. 1996. Relationship between fishes and water quality in the Pecos River, Texas. River Studies Report No. 9. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 10 pp.
Matthews, W.J. 1984. Influence of turbid inflows on vertical distribution of larval shad and freshwater drum. Trans. Amer. Fish. Soc. 113:192-198.
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 100 pp.
Meador, M.R., and W.J. Matthews. 1992. Spatial and temporal patterns in fish assemblage structure of an intermittent Texas stream. American Midland Naturalist 127(1):106-114.
Megrey, B. A. 1980. Dorosoma cepedianum (Lesueur), Gizzard shad. pp. 69 in D. S. Lee, et al. Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.
Miller, R.R. 1950. A review of the American clupeid fishes of the genus Dorosoma. Proc. U.S. Nat. Mus. 100(3267):387-410.
Miller, R.R. 1960. Systematics and biology of the gizzard shad (Dorosoma cepedianum) and related fishes. Fish. Bull. (U.S.) 60!173):371-392.
Miller, R.J., and H.W. Robison. 2004. Fishes of Oklahoma. University of Oklahoma Press, Norman. 450 pp.
Minckley, W.L., and L.A. Krumholz. 1960. Natural hybridization between the clueiod genera Dorosoma and Signalosa, with a report on the distribution of S. petense. Zoologica 45:171-180.
Riggs, C.D., and E.W. Bonn. 1959. An annotated list of the fishes of Lake Texoma, Oklahoma and Texas. The Southwestern Naturalist 4(4):157-168.
Robison, H.W., and T.N. Buchanan. 1988. Fishes of Arkansas. University of Arkansas Press, Fayetteville. 536 pp.
Santucci, V.J., Jr., and R.C. Heidinger. 1986. Use of total myomere numbers to differentiate larvae of threadfin and gizzard shad. Transactions of the Illinois Academy of Science 79(3/4):197-202.
Scharpf, C. 2005. Annotated checklist of North American freshwater fishes, including subspecies and undescribed forms. American Currents, Special Issue 31(4):1-44.
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.
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.
Whitehead, P.J.P. 1985. Clupeoid fishes of the world (suborder Clupeioidei): An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, shads, anchovies and wolf-herrings. Part 1-Chirocentridae, Clupeidae and Pristigasteridae. FAO Fish Synop. FAO species catalogue. Vol 7. 125(7/1):1-303. p233. Available online at ftp://ftp.fao.org/docrep/fao/009/ac482e/AC482E31.pdf