The American shad (Alosa sapidissima), is a species of anadromous clupeid fish naturally distributed on the North American coast of the North Atlantic, from Newfoundland to Florida, and as an introduced species on the North Pacific coast. The American shad is not closely related to the other North American shads. Rather, it seems to form a lineage that diverged from a common ancestor of the European taxa before these diversified 
The American shad has been described as "the fish that fed the (American) nation's founders". Adult shad weigh between Script error: No such module "convert". and Script error: No such module "convert". and they have a delicate flavor when cooked. It is considered flavorful enough to not require sauces, herbs or spices. It can be boiled, filleted and fried in butter, or baked. Traditionally, a little vinegar is sprinkled over it on the plate. In the eastern United States, roe shad (females) are prized because the eggs are considered a delicacy.
The shad spends most of its life in the Atlantic Ocean, but swims up fresh rivers to spawn. Northern populations are iteroparous, thus they may survive breeding, return to the sea and then return to freshwaters to spawn several more times. However, southern populations exhibit semelparity, similar to Pacific salmon. In the marine environment, shad are schooling fish. Thousands are often seen at the surface in spring, summer, and autumn. They are hard to find in the winter, as they tend to go deeper before spawning season in the range 13-18 °C.; they have been pulled up in nets as deep as Script error: No such module "convert"..
Like other herrings, the American shad is primarily a plankton feeder, but will eat small shrimp and fish eggs. Occasionally they eat small fish, but these are only a minor item in their general diet.
The sexually mature fish enter coastal rivers in spring or early summer, usually when the river water has warmed to Script error: No such module "convert".. Cooler water appears to interrupt the spawn. Consequently the shad run correspondingly later in the year passing from south to north along the coast, commencing in Georgia in January; in March in the waters tributary to Pamlico and Albemarle Sounds; in April in the Potomac; and in May and June in northern streams generally from Delaware to Canada.
In large rivers, such as the Connecticut, American shad run far upstream. The apparent longest distance is in the St. Johns River of Florida, an extremely slow (1" drop per mile, 1.5 cm per km) river that widens into large lakes; shad have been found Script error: No such module "convert". upriver.
The spawning fish select sandy or pebbly shallows and deposit their eggs primarily between sundown and midnight. Females release eggs in batches of about 30,000 eggs, though it has been estimated that as many as 156,000 eggs are deposited by very large fish. Total annual egg production is 200,000–600,000 eggs per female with larger fish producing more. In rivers north of Cape Fear the spent fish, now very emaciated, return to the sea immediately after spawning. In southern rivers, most shad die after spawning.
The eggs are transparent, pale pink or amber, and being semi-buoyant and not sticky like those of other herrings, they roll about on the bottom with the current. The eggs hatch in 12 to 15 days at Script error: No such module "convert"., in 6 to 8 days at Script error: No such module "convert"., which covers the range characteristic of Maine and Bay of Fundy rivers during the season of incubation.
The larvae are about 9 to 10 mm long. Juvenile shad remain in the rivers until fall, when they move down to salt water; they are now 1½ to 4½ inches (70 to 110 mm) long, resembling their parents in appearance.
They prefer open waters and temperatures in the range 13-18 °C. Wheeler, Timothy B. (8 May 2015). "Once nearly wiped out, shad stage an uneven comeback in the Chesapeake Bay". Baltim. Sun. Retrieved 10 May 2015 – via baltimoresun.com.
Like most herring species, American shad are very high in omega 3, and in particular contain nearly twice as much per unit weight as wild salmon. They are also very low in toxins like PCBs, dioxins, and mercury by EPA standards. The American or Atlantic shad (A. sapidissima) is a valued food fish.
There were documented declines in the Atlantic coast shad population as early as the turn of the 20th century. Traditionally, shad were caught along with salmon in set nets which were suspended from poles driven into the river bed reasonably close to shore in tidal water. Many of the rivers where shad were once common now suffer from pollution; however, the short length of time spent by shad in fresh water may minimize contamination. For example, fisheries scientists have found that shad in the Hudson River are not in the river long enough to be affected by PCBs and other contaminants (however, fishing for or possessing American Shad (including catch and release) in the Hudson River or Marine District is now prohibited). Pollution, however, may impact shad reproduction and studies have been undertaken to determine whether fingerlings suffer DNA damage.
Most of the rivers across the historic range of shad are now heavily dammed, eliminating many of the spawning grounds. For example, the number of shad harvested in the Merrimack River declined from almost 900,000 in 1789 to 0 in 1888, likely due to the inability to reach their spawning ground following a period of heavy dam construction. In recent years,[timeframe?] fish passage efforts have begun to remedy this situation, including the Chesapeake Bay Program. While recreational angling has almost no measurable impact on shad populations, shad populations are susceptible to commercial overfishing. Because of their highly migratory life history and their recreational and commercial importance, American shad are co-managed by the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and state fisheries agencies. The Atlantic States Marine Fish Commission serves as a key forum for coordinating the collective effort to conserve American shad.
Introduced in the North Pacific
American Shad were introduced into the San Francisco Bay/Sacramento River system in California in the 1800s. Shad have spread throughout many river systems on the West Coast of North America. There is currently a large shad population in the Columbia River. In recent years, shad counts at Bonneville and The Dalles Dams have ranged from over two million to over five million fish per year. Spawning shad return to the Columbia in May and June and migrate above Lower Granite Dam on the Snake River and above Priest Rapids Dam on the Upper Columbia. Unlike many introduced species, it has not been confirmed that American Shad have serious negative effects on the environment or other native fish species in the Columbia.
Shad are also valued as a sport fish that exhibit complex and little-understood feeding behavior while spawning. Unlike salmon, shad retain the ability to digest and assimilate food during the anadromous migration. Like other fish, their feeding instinct can be triggered by a variety of factors such as turbidity and water temperature. Anglers use both spinning and fly fishing tackle to pursue shad. Spin fisherman use a shad dartjig or a flutter spoon. Some anglers use a downrigger to place the artificial lure at the desired depth and location. This is usually in the channel, or deepest part of the river. Migrating shad tend to occupy the lower potion of the water column which makes this the typical depth of choice for fishing. In the North, April through June is when shad spawn in coastal rivers and estuaries once water temperatures have reached 58 degrees Fahrenheit (14 °C). Fishing conditions typically improve as water temperatures warm and flow decreases.
Society and culture
Shad serve notable symbolic roles in regional politics and culture. On the year of every gubernatorial election, would-be candidates, lobbyists, campaign workers, and reporters gather in the town of Wakefield, Virginia for Shad Planking. Similarly, in Connecticut, the towns of Essex and Windsor hold annual shad festivals.
- Froese, Rainer and Pauly, Daniel, eds. (2015). "Alosa sapidissimia" in FishBase. April 2015 version.
- Faria, R.; Weiss, S. & Alexandrino, P. (2006): A molecular phylogenetic perspective on the evolutionary history of Alosa spp. (Clupeidae). Molecular Phylogenetics and Evolution 40(1): 298–304. doi:10.1016/j.ympev.2006.02.008
- Wheeler, Timothy B. (8 May 2015). "Once nearly wiped out, shad stage an uneven comeback in the Chesapeake Bay". Baltim. Sun. Retrieved 10 May 2015 – via baltimoresun.com.
- "Grass Shad-another Fine Bait- Southeastern King Mackerel Club – King Mackerel Fishing in Southeastern North Carolina." Southeastern King Mackerel Club – King Mackerel Fishing in Southeastern North Carolina-. Web. 15 Dec. 2011. <http://southeasternkingmackerelclub.com/grass-shad-another-fine-bait/>.
- "American Shad". Fish Reference Library. Nashville, TN, USA: RedOrbit. Description. Retrieved 10 May 2015.
- New York State Freshwater Fishing 2010–2011 Official Regulations Guide
- "Hudson River Maritime Museum Kingston Shad Festival". Hudson River Maritime Museum. August 2006. Archived from the original on 20 August 2006.
- A. sapidissima (Wilson,1811) - американский шэд Позвоночные животные России. sevin.ru