Biomass: American shad, hickory shad, and blueback herring are experiencing coastwide reductions in all stocks compared to historical populations. Current spawning runs of East Coast North American shad populations have been reduced to 10 percent of historical sizes and have been extirpated from more than 4,000 km (2,500 miles) of riverine habitat. Several alosine stocks (riverine populations) are of unknown status because no directed studies have been conducted.
Overfishing: Because they are anadromous species, and tend to return to natal rivers to spawn, alosines are assessed and managed most directly by river system. Taken in total, American shad stock in particular do not appear to be recovering, but are at record lows. The lack of data makes it difficult to accurately assess most stocks.
Overfished: See above.
Fishing and habitat: American shad, hickory shad, and river herring formerly supported important commercial and recreational fisheries throughout their range. Fisheries are executed in rivers (both freshwater and saltwater), estuaries, tributaries, and oceans. Although recreational harvest data are scarce, most harvest is believed to come from the commercial industry. Commercial landings for all these species have declined dramatically from historic highs. Blockages to migration (especially dams) are the main limiting factor for spawning habitat.
By-catch: By-catch varies depending upon the gear used. The ocean intercept fishery has a high by-catch and was recently phased out.
Aquaculture: None known.
Science and Management
Currently, alosines are managed by the states (though the Maryland Department of Natural Resources, Virginia Marine Resource Commission, and Potomac River Fisheries Commission) following a fishery management plan set by the Atlantic States Marine Fisheries Commission (ASMFC). The stock is managed coastwide, with specific management actions implemented on a river-by-river basis. Young-of-the-year populations are tracked through seine surveys, but adult populations are harder to track.
Under the Interstate Fishery Management Plan for Shad and River Herring for the Atlantic Coast, commercial and recreational fisheries are closed for American shad and river herring along the Atlantic Coast unless a jurisdiction has a sustainable fisherey management plan approved by ASMFC. This plan also includes required American Shad Habitat Plans for each jurisdiction.
Historically, the fishery for American shad in particular was one of the most important on the Atlantic coast. Overfishing, reduction in spawning areas due to impediments, and poor environmental conditions led to the collapse of the fishery. Although fishery managers have been working with restoration programs to restore alosine stocks, the stocks have not seemed to recover as expected.
NOAA Fisheries conducted a review of river herring status in 2013 after a petition to list river herring as an endangered species. The 2013 review concluded that an endangered listing was not appropriate at that time. Collaboration among NOAA, ASMFC, jurisdictions, and stakeholders resulted in a River Herring Conservation Plan, published in 2015.
Life History and Habitat
Geographic Range: Along the Atlantic Coast, alosines range from the St. Lawrence River in Canada to St. John's River in Florida.
Habitat: Historically, American shad probably spawned in virtually every accessible river and tributary along the Atlantic coast. Blockage of spawning rivers by dams and other impediments and degradation of water quality, however, has severely depleted suitable American shad spawning habitat.
Life Span: Female American shad may live as long as 10 years, but repeat spawners are rare in Chesapeake Bay waters.
Food: The young of the year remain in fresh to brackish water, feeding on copepods (and other zooplankton) and terrestrial insect larvae until early fall before entering the sea. Some juveniles do not enter the sea, but rather overwinter in deep holes near the Bay mouth. While at sea, American shad feed on plankton, small crustaceans, and small fish.
Growth Rate: Growth rates are variable, depending on a combination of season, location, age, sex, and competition.
Reproduction: Spawning of American shad occurs in both tidal and nontidal freshwaters, and the spawning migration to natal streams is timed to correspond to favorable river water temperatures (55-61° F). In Virginia, spawning is generally between mid- to late March and early June. Shad usually migrate without feeding and far enough upstream that the eggs drift downstream and hatch before reaching saltwater. The American shad has a relatively high fecundity of 100,000-600,000 eggs per female. After spawning, adults either die or return to the sea. The young of the year remain in fresh to brackish water until they migrate to the ocean (usually in their first or second year), where they may spend three to six years before returning to the same river to spawn.
Migrations: Alosines are anadromous and migrate from the coastal waters to inland waters to spawn. Timing varies by species.
Predators: In the ocean, they have a variety of predators including sharks, tunas, mackerel and marine mammals, including porpoises and dolphin. In estuaries, both adult and juvenile alosines are consumed by American eel and striped bass. Juvenile herring are high quality prey for largemouth bass.
Commercial and Recreational Fishing Interest: Moratorium; catch-and-release
Distinguishing Characteristics: Most are laterally compressed, with relatively large scales. Scales on the midline of the underside form sharp scutes that produce a saw-toothed ridge. Coloration is dark bluish, greenish or bronze on the back, silvery on the sides and white below, and varies depending on color and turbidity of water. The mouth is near the midline of the snout, and a series of several dark spots usually extends backward to below the dorsal fin from near the operculum and pectoral fin. The fins are dark and without spines and the tail is deeply forked.
Role in the Ecosystem
During all life stages, alosines contribute greatly as prey to the dynamics of food chains in freshwater, estuarine, or marine habitats. While at sea, alosines are prey for many species including sharks, tunas, mackerel, and marine mammals, including porpoises and dolphin. In fresh and brackish waters, both adult and juvenile alosines are consumed by American eel and striped bass. Juvenile herring are high-quality prey for largemouth bass. As consumers, they eat a wide variety of foods, including plankton in some species such as American shad. Thus, they provide an important link between plankton and larger predatory fish.
Did You Know?
Updated June 2016