Alewife, a fish of the genus alosa (A. tyrannies, Latrobe), also called spring herring, and in the British provinces gaspereau, or American alewife. It appears in great numbers in Chesapeake bay from the south in March, on the New York and New England coasts with the shad in April, and in the British provinces about May 1. Like the shad, it ascends the northern rivers to deposit its spawn. In the bay of Fundy the alewife is abundant; in the gulf of St. Lawrence it is less common, and of smaller size; the bay of Mira-michi appears to be its extreme northern limit. It ascends rivers generally to the head of the tide, and returns to the sea in July. The fishery is prosecuted with small meshed seines drawn across the streams, and so successfully that hardly a fish escapes; the fishing lasts about six weeks, commencing as soon as the rivers are clear of ice. It prefers a soft, muddy bottom, and turbid water, and its favorite food is shrimps and the shad worm. The length of the alewife is 4 to 12 inches; the body is compressed; the head small, with golden gill covers; the eyes large, with silvery iris and black pupil; the mouth very large, the lower jaw slightly the longer, and the upper jaw deeply notched in its centre.

The color on the. back is bluish purple; the sides are light copper color, beneath silvery; on the sides are 4, 5, or even more indistinct greenish lines passing from the head to the tail; just behind the upper angle of the gill cover is a deep black spot. The scales on the body are very large, and deciduous; the entire abdominal edge is serrated by strong bony spines, largest between the ventrals and the vent; the dorsal fin is single, and the tail is deeply notched. Though thin, dry, and inferior to the herring and the shad, the alewife is a valuable fish. For home consumption, alewives are salted and smoked, like herring. The fishery in the British provinces is valuable.