Is the name of a sea fish of the Herring kind; it is also called the Mother of Herrings; by some authors Clupea and Trissa; by the Ancients Trechis, or Trichias; and the Clupea Alosa of Linnæus. In its general form, it very much resembles the Herring; only it is flatter and broader, and grows to a cubit long and four inches broad. The back is convex and rather sharp; the head sloping considerably from it. The body grows gradually less to the tail from thence. The lower jaw is rather longer than the upper; the teeth very minute. The dorsal fin is small, and placed very near the center: the middle rays are the longest. The pectoral and ventral fins are small; the belly very sharp; the tail forked: the body is of a dusky blue. Above the gills is a line of black spots, which mark the upper part of the back on each side. The number of these spots is different in different fish, from four to ten.

It is very common in many of our seas, and in some of our rivers which lie near the sea. They run up there in great numbers, and are then very fat; they afterwards become lean, and go down to the sea again. They usually swim in large shoals together.

The Shad is in higher perfection in the Severn than in any other river in Great Britain. It appears there in May, and in very warm seasons, in April; it continues about two months. At its first appearance, it is esteemed a very delicate fish; especially at Gloucester, where it sells dearer than Salmon. The London fishmongers distinguish it from that of the Thames by the French name of Alose. Whether they spawn in the Severn and Wye, is not determined, as their fry has not yet been ascertained. The old fish come from the sea in full roe.

The fishermen imagine, very erroneously, that the Bleak, which appear in multitudes near Gloucester in the months of July and August, are the fry of the Shad: many of these are taken in those months only; but none of the emaciated Shad are ever caught in their return.

The Thames Shad does not frequent the river till the month of July, and is thought a very coarse, insipid fish. At that time, the Twaite, a variety of Shad which makes its appearance in Gloucester, and is taken in great numbers in the Severn, but held in as great disrepute as the Shad of the Thames. The real Shad weighs sometimes eight pounds; but in general from four to five. The Twaite, on the contrary, weighs from half a pound to two pounds, which it never exceeds. It only differs from the small Shad, by having one or more black spots on its side, which are generally placed one under the other.