Alewives have a short jaw that juts out when the mouth is closed. Spawning occurs in early spring when large schools of alewives move into tidal waters from the ocean. These spawning runs begin slowly with only a few fish at a time migrating in. As more fish arrive, they remain along the shore in the main rivers. Spawning fish can often be seen swirling about in small groups.
Young alewives are often hard to find, as they hide in weedy beds and deep water during the day.
Like shad, as fall approaches they leave the estuary and migrate out to the ocean. Alewives are found all along the eastern Atlantic Ocean from Newfoundland to North Carolina. They follow the same general pattern of migration as shad, moving north in early summer and south in the fall. These fish spend two to three years at sea before returning home to spawn. It is thought that they move off the east coast and wander over most of the Continental Shelf.