American gizzard shad
|American gizzard shad|
|American gizzard shad|
Like other gizzard shads, the body is deep somewhat forward of the middle. It is a grayish or silvery blue above, becoming silver on the sides and white below. The dorsal fin has 10-12 rays; in adults, the last ray is very long, extending beyond the rest of the fin. The caudal fin is deeply forked. They can reach a length of 22.5 inches (57 cm), and weigh up to 4.37 lbs (1980 grams). 15% of D. cepedianum breeds in its second year about 59,000 eggs, the rest about 379,000 in its third year.
American gizzard shad begin life feeding on zooplankton, using their teeth to catch them. At about 1 inch in length, they lose the teeth, become deeper-bodied, develop the muscular gizzard, and become filter feeders, consuming both small invertebrates and phytoplankton, as well as some sand for the gizzard.
They live in a variety of open waters, both clear and silty, including rivers, swamps, lakes, and bays, typically near the surface. They avoid fast-moving water, But have been witnessed in large schools near, and under, dams, warm water outlets, and turbine outflows.
Native range extends from the Great Lakes and St. Lawrence River area west to eastern South Dakota and central New Mexico, as well as to the Gulf of Mexico, where it has been found as far south as Rio Panuco in Mexico.
The specific epithet cepedianum honors French naturalist Bernard Germain de Lacépède (1756-1825).
Forage Fish Controversy
|This article may contain inappropriate or misinterpreted citations that do not verify the text. (May 2009)|
Gizzard shad are a preferred food of the largemouth bass, an economically important sport fish, and they reproduce rapidly. For this reason, it is widely believed that bass fishing is best where gizzard shad are abundant. The practice of introducing gizzard shad to improve bass fishing is controversial.
Gizzard shad do provide large bass with a steady supply of quality food. They grow faster than bluegill and are easier for bass to swallow, so large bass (approx. five pounds or larger) benefit from shad introduction. Also, by providing bass with alternate prey, they reduce predatory pressure on young bluegill. However, in public lakes with heavy fishing pressure, gizzard shad are of questionable value because they grow quickly and can easily grow too large for most bass to swallow.
Due to conflicting results in many field experiments, their value as a forage fish is questionable.
- William F. Sigler and John W. Sigler, Fishes of Utah (University of Utah Press, 1996), pp. 59–62
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Dorosoma cepedianum" in FishBase. October 2006 version.
- Doug Keller, "The Truth about Shad." Outdoor Indiana, May/June 2006, pp. 37–39.
- "Stocking Gizzard Shad for Trophy Bass," Kedric Nutt. Retrieved 3/14/2008.
- Elements of Ecology, 6th edition, Robert Leo Smith, Thomas M. Smith, Pearson Education, Inc., Benjamin Cummings, 2006; Italian version Elementi di Ecologia, Pearson Paravia Bruno Mondadori S.p.A, 2009, page 172