The following spring they migrate northward to the Chesapeake Bay area and into New England waters. Atlantic menhaden are the most important and one of the most abundant fish species in the Chesapeake Bay. During summer months, these fish swim in large schools and their silvery bodies can often be seen near the water's surface. Juveniles primarily feed on zooplankton, but adults are mainly herbivores, but retain the ability to feed on zooplankton. The adults are very adaptable and will feed on several species of phytoplankton, as well as suspended organic plant detritus.
Atlantic menhaden are an ecologically critical fish species.
They consume and redistribute a significant amount of energy within and between the Chesapeake Bay and other estuaries, and the coastal ocean. This is due, in part, to their tremendous numbers, individual growth rate, filter feeding capacity, and seasonal movements. An adult fish can filter up to a million gallons of water every 180 days. Menhaden are also an extremely important prey species for many predatory fish such as striped bass, bluefish, weakfish, and spanish mackerel. Because or their schooling behavior, they are also a favorite target for the common loon, herons, egrets, ospreys, and eagles.