Dorosoma cepedianum thrives in rivers, streams, reservoirs and lakes in the mid to eastern region of the United States and the middle and south of Canada around the Great Lakes. It can also be found all the way down to central Mexico and Florida.

(Murdy et al. 1997)

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: St. Lawrence-Great Lakes, Mississippi River, Atlantic, and Gulf drainages from Quebec to North Dakota and New Mexico, south to central Florida and Mexico; introduced outside native range; common (Page and Burr 1991). Mexico.

D. cepedianum grows to be about nine to fourteen inches long as an adult, and only four inches long as a juvenile. Usually, the adult eventually grows to be about two pounds.

D. cepedianum juvenile has a different appearance than the adult. The juvenile has a dark spot on its shoulder, but this marking fades as the fish grows. The adult's body is oblong shaped and is laterally compressed. It is usually silvery blue dorsally, silver on the sides, and dusky white ventrally. The last ray of the dorsal fin rays is long and thin; it resembles a whip. Its caudal fin has a deep fork in it. Its head is rounded and blunt on the front and its mouth is subterminal. Like many fish, there are no teeth. This fish has no lateral line.

(Konrad 2001)

Average mass: 1089 g.

Length: 35 cm

This is mostly a freshwater fish, usually living in lakes, ponds, rivers, streams, and reservoirs. However, it lives in the Chesapeake Bay, and there it is anadromous, meaning it lives in both salty and freshwaters. In the bay, it spends most of the time in the salty lower region, and migrates up the bay to the freshwater regions to breed in the spring. This fish prefers brakish, not densely vegetated areas of deep waters to live as adults, and juveniles live in the more clear and shallower waters when they are calm. The lakes that D. cepedianum occupy are mostly soft-bottomed with a lot of mud and sediment. The ideal temperature for gizzard shad to live in is between 50 and 70 degrees F, or 10 and 21 degrees C. If the temperature drops to around 2 or 3 degrees C, D. cepedianum will die.

(Konrad 2001, Lippson 1997)

Aquatic Biomes: lakes and ponds; rivers and streams

Habitat Type: Freshwater

Comments: Medium to large rivers, reservoirs, lakes, swamps, bays, sloughs, and similar quiet open waters, from clear to very silty; an open water species; often ascends creeks and small rivers that have well-developed pools; commonly enters brackish water (Page and Burr 1991). Juveniles occur in quiet surface waters, adults in deeper water or near bottom (Sublette et al. 1990). Spawns in shallow water usually over sandy/rocky substrates; eggs scattered, adhere to objects (Sublette et al. 1990). May ascend smaller streams or ditches to spawn. Has spawned in 1 m of water over sandy rocky bar in Lake Erie (Becker 1983).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

An adult D. cepedianum is primarily an omnivore. It is a filter feeder using the 190 rakers on the first gill arch's lower limb. It feeds mostly on phytoplankton and zooplankton, such as perphyton, chrysophyta, and rotifera. Since this fish filters the surrounding water and sediment for food, it also ingests and digests detritus. The substance on the freshwater bed is known as ausfwulchs assemblage, which is what gizzard shad feed on. Sediment and sand are also ingested by the gizzard shad that helps it to digest food in its muscular gizzard.

(Klingel 1990, Konrad 2001)

Comments: Juveniles are nonvisual planktivores, taking protozoans, small crustaceans, Chlorophyta, and Chrysophyta (Sublette et al. 1990). Adults primarily bottom filter-feeding detritivores; eat large quantities of material from aufwuchs assemblage, especially from littoral areas; also takes phytoplankton in open water (Sublette et al. 1990).

Travels in schools. Important source of food for piscivorous fishes and for certain waterfowl (e.g., mergansers) (Sublette et al. 1990).

Average lifespan

Status: wild: 10.0 years.

D. cepedianum reproduces like many fish and even mammals do: one female mates with many males to ensure fertilization. The female is prolific. She mates randomly and does not stay around to care for her young. Gizzard shad reproduce during spawning season, which is in the spring between late April and early August. They mate nocturnally. Also, they prefer to spawn over sandy and rocky substrates so the eggs will have a surface to adhere to once they are laid. Furthermore, the temperature of the water should be around 21 degrees Celsius for optimum breeding conditions. The fish will spawn in shallow water, usually less than 1.2 meters deep. After mating, up to 400,000 eggs are released in the shallow, clear, and calm waters of the freshwater environment. The D. cepedianum incubation period is two to four days, depending on the water temperature and environmental conditions. The young hatch in the larval stage, develop into the juvenile stage, and then on to the adult stage. The young reach sexual maurity after one year. Breeding is random, so there is no social system to D. cepedianum spawning.

(Klingel 1990, SCBASS Federation 2001)

Average age at sexual or reproductive maturity (male)

Sex: male: 730 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 730 days.

Spawns at night, spring to summer. Eggs hatch in about 2-4 days. Sexually mature usually in 2-3 years. Life span generally about 4-6 years; few survive beyond age III (Sublette et al. 1990).

Gizzard shad are currently not in any need of special protections.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Generally, D. cepedianum is viewed as a trash fish that is simply a nuisance. Not many sports fish eat the adult gizzard shad. Actually, the only fishes that do eat this fish are catfish and striped bass. The young shad is usually in competition with the valuable sports fishes that co-exist in the same habitat. In fact, one study shows that D. cepedianum eats young crappie (a more valuable fish) in Texan reservoirs. This factor decreases the gizzard shad's usefulness to humans.

(Drenner 1990, Konrad 2001, SCBASS Federation 2001)

Humans use D. cepedianum as bait to catch larger fish. This fish is sold as a basic live or cut bait. Also, larger pelagic sport fishes eat gizzard shad, which keeps the human sportfishing industry up.

(Bonds 1998, SCBASS 2001)