fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
, the river herrings, in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Clupeidae
Clupeidae is a family of ray-finned fishes, comprising, for instance, the herrings, shads, sardines, hilsa, and menhadens. The clupeoids include many of the most important food fishes in the world, and are also commonly caught for production of ...
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
and the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
. Also, several taxa occur in the brackish-water
Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
and the
Black Sea
The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...
basin. Many are found in fresh water during spawning and some are only found in landlocked fresh water.
Fossil record
These fishes lived from the
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
to
Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
(from 55 million years ago to now). Fossils have been found in Canada, the United States, Greece, Kazakhstan, Azerbaijan, Hungary, Romania, and Italy.
Appearance
''Alosa'' species are generally dark on the back and top of the head, with blue, violet, or greenish tints. Some can be identified as having a grey or green back. Spots are commonly found behind the head, and the fins may vary from species to species or individually. Most species of ''Alosa'' weigh or less, with one species, ''A. pontica'', weighing up to 2 kg.
Biology
Shads are thought to be unique among the fishes in having evolved an ability to detect
ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
(at frequencies above 20 kHz, which is the limit of human hearing).Mann, D. A.; Higgs, D. M.; Tavolga, W. N.; Souza, M. J.; and Popper, A. N. (2001). Ultrasound detection by clupeiform fishes. ''Journal of the Acoustical Society of America'' 109:3048–3054 This was first discovered by fisheries biologists studying a type of shad known as
blueback herring
The blueback herring, blueback shad, or summer shad (''Alosa aestivalis'') is an anadromous species of herring from the east coast of North America, with a range from Nova Scotia to Florida. Blueback herring form schools and are believed to mi ...
, and was later verified in laboratory studies of hearing in American shad. This ability is thought to help them avoid
dolphins
A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (t ...
that find prey using echolocation. ''Alosa'' species are generally
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
. They are mostly
anadromous
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...
or semianadromous with the exception of strictly freshwater landlocked species. ''Alosa'' species are generally migratory and schooling fish. Males usually mature about a year before females; they spawn in the late spring to summer. Most individuals die shortly after spawning. ''Alosa'' species seemingly can change readily to adapt to their environments, as species are found in a wide range of temperatures and waters.
Lifecycle and reproduction
As ''Alosa'' species are generally anadromous, they face various obstacles to survival.Lochet, A., S. Boutry, and E. Rochard. ''Estuarine Phase during Seaward Migration for Allis Shad Alosa Alosa and Twaite Shad Alosa Fallax Future Spawners.'' Ecology of Freshwater Fish 18 (2009): 323-35. They may have to pass through numerous barriers and waters to get to either their spawning grounds or normal habitats (the sea in most cases). Estuaries are a major factor in numerous ''Alosa'' species' migrations. Estuaries can be highly variable and complex environments contributing to fluctuating biological interactions, with shifts in osmolarity, food sources, predators, etc. Since many adult ''Alosa'' species die after spawning, only the young generally to migrate to the sea from the spawning grounds. Duration of migration varies among fish, but can greatly affect survival.
Reproduction varies by species. Studies done on ''Alosa'' in Iranian waters have shown that spawning varies in time, place, and temperature of the waters they inhabit. Fecundity may also vary. Species are known to spawn as early as April or as late as August. Temperatures range from about 11 to 27 °C. Fecundity can range from 20,000 to 312,000 eggs. Eggs are pelagic. Geography and temperature are important environmental factors in egg and young-of-year development.
The lifespan of ''Alosa'' species can be up to 10 years, but this is generally uncommon, as many die after spawning.
Systematics
The systematics and distribution of ''Alosa'' shads are complex. The genus inhabits a wide range of
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s, and many
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
are migratory. A few forms are landlocked, including one from
Killarney
Killarney ( ; ga, Cill Airne , meaning 'church of sloes') is a town in County Kerry, southwestern Ireland. The town is on the northeastern shore of Lough Leane, part of Killarney National Park, and is home to St Mary's Cathedral, Ross Castl ...
in
Ireland
Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
, two from lakes in northern Italy, and two in
Greece
Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...
. Several species are native to the Black and Caspian Seas. ''Alosa'' species of the Caspian are systemically characterized by the number of rakers on the first gill arch.Malkin, E. M., and S. B. Andrianova. ''Biology and Traits of the Formation of Stock of Big-eyed Shad Alosa Saposchnikowii.'' Journal of Ichthyology 48.6 (2008): 443-51. They are classified as being "multirakered", "medium-rakered", or "oligorakered". The multirakered are primarily plankton feeders, the oligorakered have large rakers and are predators, and the medium-rakered generally consume a mixed diet. Most current species of the genus ''Alosa'' in North America can be found in Florida, whereas the distribution of most of them is broader.Richard S. McBride (2000). ''Florida's Shad and River Herrings (Alosaspecies): A Review of Population and Fishery Characteristics''. Florida MAR8INE Research Institute Technical Reports: Technical Report TR-5, Florida Fish and Wildlife Conservation Commission. St. Petersburg, Florida.
Morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
is notoriously liable to
adapt
ADAPT (formerly American Disabled for Attendant Programs Today) is a United States grassroots disability rights organization with chapters in 30 states and Washington, D.C. They use nonviolent direct action in order to bring about disability just ...
to changing food availability in these fish. Several taxa seem to have evolved quite recently, making molecular analyses difficult. In addition,
hybridization
Hybridization (or hybridisation) may refer to:
*Hybridization (biology), the process of combining different varieties of organisms to create a hybrid
*Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals
*Nu ...
may be a factor in shad
phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
.Faria, R.; Weiss, S.; and Alexandrino, P. (2006). ''A molecular phylogenetic perspective on the evolutionary history of ''Alosa'' spp. (Clupeidae).'' ''Molecular Phylogenetics and Evolution'' 40(1): 298–304. (HTML abstract). Nonetheless, some trends are emerging. The North American species except the
American shad
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 ...
''A. sapidissima'' can probably be separated in a
subgenus
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
''Pomolobus''. Conversely, the proposed genus (or subgenus) ''Caspialosa'' for the
Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
forms is rejected due to
paraphyly
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
Rafinesque
Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultimat ...
Alosa agone
''Alosa agone'' is a species of ray-finned fish in the genus ''Alosa
''Alosa'' is a genus of fish, the river herrings, in the family Clupeidae. Along with other genera in the subfamily Alosinae, they are generally known as shads. tp://ftp. ...
'' (
Scopoli
Giovanni Antonio Scopoli (sometimes Latinized as Johannes Antonius Scopolius) (3 June 1723 – 8 May 1788) was an Italian physician and naturalist. His biographer Otto Guglia named him the "first anational European" and the "Linnaeus of the Au ...
Regan
The family name Regan, along with its cognates O'Regan, O Regan, Reagan, and O'Reagan, is an Anglicized form of the Irish surname Ó Riagáin or Ó Ríogáin, from Ua Riagáin. The meaning is likely to have originated in ancient Gaelic ''ri'' ...
Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
, 1758) (allis shad)
* ''
Alosa fallax
The twait shad or twaite shad (''Alosa fallax'') is a species of fish in the family Clupeidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea and is an anadromous fish which lives in the sea but migrates into fresh water to s ...
Suvorov
Alexander Vasilyevich Suvorov (russian: Алекса́ндр Васи́льевич Суво́ров, Aleksándr Vasíl'yevich Suvórov; or 1730) was a Russian general in service of the Russian Empire. He was Count of Râmnicu Sărat, Rymnik, C ...
Grimm
Grimm may refer to:
People
* Grimm (surname)
* Brothers Grimm, German linguists
** Jacob Grimm (1785–1863), German philologist, jurist and mythologist
** Wilhelm Grimm (1786–1859), German author, the younger of the Brothers Grimm
* Christian ...
Alosa maeotica
''Alosa maeotica'', known as the Black Sea shad or Azov shad, is a species of clupeid fish endemic to the Sea of Azov and the western part of the Black Sea basin. It is found in Bulgaria, Georgia, Moldova, Romania, Russia, Turkey, and Ukraine
...
Alosa tanaica
''Alosa tanaica'', called in English the Azov shad or Black Sea shad, is a species of clupeid fish endemic to the Ponto-Caspian basin. It is an anadromous species, spawning in the lower reaches of rivers. It is widespread in the eastern Black ...
Shad populations have been in decline for years due to spawning areas blocked by dams, habitat destruction, pollution, and
overfishing
Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...
. Management of shad has called for more conservative regulations, and policies to help the species have lower fishing mortality.
Political significance
Shad serve a peculiar symbolic role in
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
state politics. On the year of every gubernatorial election, would-be candidates, lobbyists, campaign workers, and reporters gather in the town of
Wakefield, Virginia
Wakefield is an incorporated town in Sussex County, Virginia, United States. Per the 2020 census, the population was 729.
Wakefield is widely known for the Virginia Diner, the Airfield Conference and 4-H Educational Center, and the National We ...
, for
shad planking
The Shad Planking is an annual political event in Virginia which takes place every April near Wakefield in Sussex County. It is sponsored by a chapter of the Ruritans, a community service organization which was founded in the small town of Hollan ...
. American shad served as the focal point of
John McPhee
John Angus McPhee (born March 8, 1931) is an American writer. He is considered one of the pioneers of creative nonfiction. He is a four-time finalist for the Pulitzer Prize in the category General Nonfiction, and he won that award on the fourth ...
's book ''The Founding Fish''.
Culinary use
The
roe
Roe ( ) or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses, of fish and certain marine animals such as shrimp, scallop, sea urchins and squid. As a seafood, roe is used both as a cooking, coo ...
, or more properly the entire engorged uterus of the
American shad
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 ...
—filled with ripening eggs, sautéed in clarified butter and garnished with parsley and a slice of lemon—is considered a great delicacy, and commands high prices when available.
See also
*
The Shad Foundation The Shad Foundation is an international non-profit 501(c)(3) organization established in 1996 for the study, protection, and celebration of shads around the world. Currently, there are more than 30 recognized shad species worldwide. tp://ftp.fao.or ...