Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic). American Shad.
GEORGIA COOPERATIVE FISHERY AND WILDLIFE RESEARCH UNIT ATHENS
Pagination or Media Count:
Species profiles are literature summaries of the life history, distribution, and environmental requirements of coastal fishes and invertebrates. Profiles are prepared to assist with environmental impact assessment. The American shad Alosa sapidissima was the most valuable food fish on the Atlantic coast prior to the 1940s but landings have declined drastically since that time, and sport fishing has become more important than commercial fishing in most rivers where stocks still exist. The American shad is anadromous adults congregate offshore in areas within the North Atlantic Bight during summer, move southward in coastal waters during fall and early winter, and move up rivers to spawn during late winter and spring. In rivers in the South Atlantic Region, the spawning run peaks during January and February, but can continue through April and May. Larval shad live in upriver aras and eat a variety of small invertebrates, Juveniles gradually move downriver and live in estuaries, where they grow to about 100 mm in length and migrate to sea where they live 3-5 years before maturing. Most American shad return to ther natal river to spawn and in the South Atlantic Bight, most adults die after spawning once. Development of eggs requires water temperatures of 14 to 21 C, dissolved oxygen concentration of at least 5 mglo, and current velocities capable of buoying eggs during incubation. Downstream transport of the young and spawning migrations of adults can be adversely affected by excessive alteration of the river flow.
- Biological Oceanography