Connecticut River Coordinator's Office
Northeast Region
 
Photo of American shad viewed through a window at the Holyoke Dam - Photo credit:  U.S. Fish and Wildlife Service
Photo of American shad viewed through a window at the Holyoke Dam. Credit: USFWS

Description

The gizzard shad (Dorosoma cepedianum) is relatively new to the Connecticut River (see STATUS). Gizzard shad look similar to American shad, but tend to be somewhat smaller and are less delicate. Their snout is relatively blunt and the last ray of the dorsal fin is extended. They may reach lengths of 20 inches and weigh up to 7 pounds.

Gizzard Shad. Credit: USFWS
Gizzard Shad. Credit: USFWS

Life History

Although gizzard shad migrate upriver in the springtime, the full migratory strategy of the gizzard shad in the Connecticut River system is unclear. Truly anadromous (migrating from the ocean to freshwater specifically to reproduce) populations exist further south but have not been documented in the Connecticut River. Though spawning is known to occur in Massachusetts, this may be the activity of established freshwater populations. Freshwater populations of gizzard shad are generally found in ponds, lakes, pools, or slow-moving waters. Gizzard shad prefer warm water. Spawning occurs in late spring and early summer as water temperature increases.

Distribution

The gizzard shad is found in freshwaters throughout much of eastern and central North America. In the Connecticut River, gizzard shad are found in the mainstem up to Bellows Falls Dam (175 miles from the mouth). Anadromous populations occur along the mid-Atlantic coast.

Status

The gizzard shad is a newcomer to the Connecticut River watershed. This species has naturally expanded its range northward to the Connecticut River, where it was first observed at the mouth in 1980. By 1986, it had expanded its range to the Holyoke Dam. Since then, populations counted at the Holyoke Dam have grown from 27 in 1986 to 2,100 in 1997 (see Migratory Fish Return Numbers).

Restoration Efforts

Though gizzard shad have benefited from fish passage facilities in the Connecticut River watershed, there are no current programs specifically designed to increase gizzard shad populations. In fact, because of their invasive tendencies, some fisheries managers are concerned about the threat of gizzard shad to other fish populations. In more southerly river systems, gizzard shad have become so prolific that they place a strain on existing fish passage facilities that were designed for less numerous species.

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Last updated: September 8, 2010
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