shad fly: see mayfly.

shad, fish, Alosa sapidissima, of the family Clupeidae (herring family), found along the Atlantic coast from Newfoundland to Florida and successfully introduced on the Pacific coast. The shad is one of the largest (6 lb/2.7 kg average) of the herrings and has delicious but bony flesh; its roe is valued as a delicacy. Shad ascend rivers to spawn in the spring; water pollution and indiscriminate netting have cut down their numbers. The gizzard shad, Dorosoma (named for its muscular gizzardlike stomach), a swift, silvery fish, 1 ft (30 cm) long, is found along the Atlantic coast from New Jersey to Texas and up the Mississippi to the Great Lakes. Shads are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Clupeiformes, family Clupeidae.

Any of several saltwater food fishes of the herring family (Clupeidae) that swim up rivers to spawn. Shad eggs (roe) are a delicacy in the U.S. Adult shad are toothless. The lower jaw of shad in the genus Alosa fits into a notch at the tip of the upper jaw. The American shad (A. sapidissima), an Atlantic fish introduced into the Pacific, is a migratory plankton eater and a good game fish. The Allis (or Allice) shad (A. alosa) of Europe is about 30 in. (75 cm) long and weighs about 8 lbs (3.6 kg). Seealso whitefish.

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