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AMERICAN SHAD

DID YOU KNOW? American shad was introduced in the Pacific Northwest in the late 1800's, and in 1990 the population of shad entering the Columbia River was over 4 million fish.

SCIENTIFIC NAME: Alosa sapidissima, alosa is an old name for European shad and sapidissima meaning most delicious.

COMMON NAMES: Atlantic shad, Potomac shad, white shad, common shad, North river shad, and Connecticut river shad.

DESCRIPTION: A compressed silvery fish with a row of dark spots (3-23) along its side. It can be easily distinguished by its sharp saw-like scales or "scutes" along its belly. Average sized shad are 12-25 inches in length and 2.5 to 5 pounds.

LIFECYCLE: The American shad is a highly migratory anadromous species that returns to its freshwater natal (birth) areas to spawn. Shad spawn in estuaries, streams, and rivers in the spring and early summer months. Spawning usually takes place over gently sloping areas with fine gravels or sandy bottoms. In small groups; males and females disperse eggs and sperm together and fertilization takes place in the water column. Males and females may return to spawn more than once, and female shad can produce 30,000 to 600,000 eggs. The fertilized eggs float downstream and hatch in 3 to 10 days. Juvenile shad tend to survive best in the slow waters of reservoirs. They migrate downstream towards the ocean during late summer and fall, with most migrating to the open ocean before winter. Some shad will reside in rivers and estuaries up to one year before entering the ocean. Shad normally spend 3-4 years at sea before returning to spawn.

RANGE: Along the Pacific coast from California to Alaska.

HABITAT AND ECOLOGY: The construction of dams on the Columbia river basin has contributed to the decline of almost all species of anadromous fish except the shad. Since the completion of the lower Columbia river dams, shad populations have been on the rise. The slow moving waters of reservoirs apparently provide ideal conditions for juvenile shad.

The shad is a plankton feeder who's diet varies depending upon the geographical region. Throughout its life a shad consume copepods, amiphipods, shrimp, zooplankton, and other small fishes. In freshwater the shad itself falls prey to white sturgeon, juvenile salmonids, harbor seals, and other predators, while in the ocean phase of life a shad is preyed upon by sharks, tuna, sea lions, and others.

The American shad is very temperature sensitive and any changes in the temperature of its habitat may result in negative impacts. Reservoirs often act as ideal rearing habitat for juveniles; however, fish ladders, and dam bypass systems are necessary to assist in migration past dams. Water irrigation projects may also negatively impact shad populations.

ECONOMIC VALUE: Sport fisheries for shad have been building for years in the Pacific Northwest. Shad are used as bait for other fisheries and it is considered a good fighting sportfish that is rich in flavor and is known for its excellent roe. Commercial fisheries have existed in the Columbia River since the 1930's. Due to poor market demand and incidental catches of protected salmon runs, significant commercial fisheries do not exist in the Pacific Northwest.


Revised 12/16/96