Alosa

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Genus of fishes

title: "Alosa" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["alosa", "commercial-fish", "extant-eocene-first-appearances", "marine-fish-genera", "ray-finned-fish-genera"] description: "Genus of fishes" topic_path: "general/alosa" source: "https://en.wikipedia.org/wiki/Alosa" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of fishes ::

| name = Alosa | fossil_range = Potential Late Eocene occurrence | image = Alosa fallax.jpg | image_caption = Twaite shad, Alosa fallax | taxon = Alosa | authority = H. F. Linck, 1790 | type_species = * Clupea alosa* | type_species_authority = Linnaeus, 1758 | subdivision_ranks = Species | subdivision = See text. | synonyms = {{Genus list | Pomolobus | Rafinesque, 1820 | Alausa | Valenciennes, 1847 | Alausella | Gill, 1861 | Caspialosa | Berg, 1915 | Paralosa | Roule, 1925 | synonyms_ref =

Alosa is a genus of fish, the river herrings, in the family Alosidae. Along with other genera in the subfamily Alosinae, they are generally known as shads. They are distinct from other herrings by having a deeper body and spawning in rivers. Several species can be found on both sides of the Atlantic Ocean and the Mediterranean Sea. Also, several taxa occur in the brackish-water Caspian Sea and the Black Sea basin. Many are found in fresh water during spawning and some are only found in landlocked fresh water.

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 300 g or less, with A. pontica and A. fallax weighing up to 2 kg, and A. alosa can exceed 3–4 kg.

Biology

Shads are thought to be unique among the fishes in having evolved an ability to detect ultrasound (at frequencies above 20 kHz, which is the limit of human hearing). This was first discovered by fisheries biologists studying a type of shad known as blueback herring, and was later verified in laboratory studies of hearing in American shad. This ability is thought to help them avoid dolphins that find prey using echolocation. Alosa species are generally pelagic. They are mostly anadromous or semianadromous with the exception of strictly freshwater landlocked species. 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. 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 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.

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 habitats, and many taxa are migratory. A few forms are landlocked, including one from Killarney in Ireland, two from lakes in northern Italy, and two in Greece. 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. They are classified as being "multirakered", "medium-rakered", or "oligorakered".

Morphology is notoriously liable to adapt to changing food availability in these fish. Several taxa seem to have evolved quite recently, making molecular analyses difficult. In addition, hybridization may be a factor in shad phylogeny. Nonetheless, some trends are emerging. The North American species except the American shad A. sapidissima can probably be separated in a subgenus Pomolobus. Conversely, the proposed genus (or subgenus) Caspialosa for the Caspian Sea forms is rejected due to paraphyly.

Species by geographical origin

North America

Western Europe and the Mediterranean

Caspian Sea, Black Sea, the Balkans

Fossil species

::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/54/Clupeidae_-_Alosa_elongata.JPG" caption="website=paleobiodb.org}}"] ::

The former fossil species A. ovalis Rückert-Ulkümen, 1965 is now placed in Clupeonella as Clupeonella ovalis. The taxonomy of some of these other fossil species is also uncertain; A. fortipinnata appears most closely related to Brevoortia, while A. crassa and A. sculptata cannot be reliably placed in the genus either. However, A. elongata appears to be a definitive member of the genus.

Recreational fishing

Commercial fishing

::data[format=table]

Commercial capture production of wild shad in tonnes.1999200020012002200320042005200820102011201220132014
788,770860,346665,284589,692524,800569,160605,548588,978645,977611,371604,842628,622636,678
::

Management

Shad populations have been in decline for years due to spawning areas blocked by dams, habitat destruction, pollution, and overfishing. Management of shad has called for more conservative regulations, and policies to help the species have lower fishing mortality.{{cite web |url = http://www.asmfc.org/shadRiverHerring.htm |title = Atlantic States Marine Fisheries Commission: Shad |access-date = 2009-06-30 |archive-url = https://archive.today/20130414063741/http://www.asmfc.org/shadRiverHerring.htm |archive-date = 2013-04-14 |url-status = dead

Political significance

Shad serve a peculiar symbolic role in Virginia state politics. 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. American shad served as the focal point of John McPhee's book The Founding Fish.

Culinary use

::figure[src="https://upload.wikimedia.org/wikipedia/commons/d/de/Shad_roe.jpg" caption="Shad roe"] ::

The American shad’s egg sacs, known as shad roe, are a seasonal springtime ingredient traditionally sautéed in butter and served with lemon and parsley. Due to their short availability and unique, rich texture, they are considered a specialty, commanding higher prices in early spring when the female fish migrate up rivers to spawn. These delicate, lobe-shaped, or ribbon-like, sets are typically cooked carefully to maintain their structure, resulting in a savory, mild flavor that is often paired with bacon or other rich ingredients.

References

References

  1. Sepkoski, Jack. (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology.
  2. {{Cof family
  3. "''Alosa'' Linck, 1790".
  4. "Alosinae".
  5. Whitehead, Peter J.P.. (1985). "FAO species catalogue. Vol. 7. Clupeoid fishes of the world. An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, anchovies and wolfherrings. Part 1 – Chirocentridae, Clupeidae and Pristigasteridae". FAO.
  6. (2001). "Ultrasound detection by clupeiform fishes". The Journal of the Acoustical Society of America.
  7. (2001). "Shad Species In Greek Waters – An Historical Overview And Present Status". Bulletin Français de la Pêche et de la Pisciculture.
  8. Ingram, Travis R.. (2007). "Age, growth and fecundity of Alabama shad (''Alosa alabamae'') in the Apalachicola River, Florida". Clemson University.
  9. Bianco, P. G.. (2002). "The Status of the Twaite Shad, ''Alosa agone'', in Italy and the Western Balkans". Marine Ecology.
  10. (2009). "Estuarine phase during seaward migration for allis shad ''Alosa alosa'' and twaite shad ''Alosa fallax'' future spawners". Ecology of Freshwater Fish.
  11. Coad, Brian. (1997). "Shad in Iranian Waters". [[Shad Journal]].
  12. (October 2020). "Growth models and growing degree-days: assessment of young-of-year Alewife and Blueback Herring in Potomac River tributaries". Environmental Biology of Fishes.
  13. (2008). "Biology and traits of the formation of stock of big-eyed shad ''Alosa saposchnikowii''". Journal of Ichthyology.
  14. 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.
  15. (2006). "A molecular phylogenetic perspective on the evolutionary history of ''Alosa'' spp. (Clupeidae)". Molecular Phylogenetics and Evolution.
  16. Bagils, R. Zaragüeta. (2001). "LES ALOSA FOSSILES ET LA NOTION DE GENRE EN SYSTÉMATIQUE PHYLOGÉNÉTIQUE.". Bulletin Français de la Pêche et de la Pisciculture.
  17. Rückert-Ülkümen, Neriman. (1994). "Zur systematischen Stellung einiger Clupeidae aus Thrakien, Türkei". Mitteilungen der Bayerischen Staatssammlung für Paläontologie und historische Geologie.
  18. "PBDB Taxon".
  19. (2015-12-01). "Fish otoliths from the Konkian (Miocene, early Serravallian) of Mangyshlak (Kazakhstan): testimony to an early endemic evolution in the Eastern Paratethys". Paläontologische Zeitschrift.
  20. "Clupeid scales from the Menilite Beds (Palaeogene) of the Carpathians - Acta Palaeontologica Polonica".
  21. Kevrekidis, Charalampos. (2024-11-01). "Uncovering the relationships among herring-like fossils (Clupei: Teleostei): a phylogenetic analysis". Zoological Journal of the Linnean Society.
  22. [[FAO]] (2006) [https://web.archive.org/web/20170518134931/ftp://ftp.fao.org/FI/STAT/summary/default.htm ''Yearbooks of Fishery Statistics Summary Tables'']
  23. [[FAO]] (2014) [https://web.archive.org/web/20170518134923/ftp://ftp.fao.org/FI/STAT/summary/a1d.pdf ''Yearbook - Fishery and Aquaculture Statistics''], no. 24.
  24. "American Shad - Fish Reference Library - RedOrbit." RedOrbit - Science, Space, Technology, Health News and Information. 3 Apr. 2007. Web. 27 Nov. 2011. http://www.redorbit.com/education/reference_library/science_1/fish/2579052/american_shad/index.html.
  25. singlegirldin. (2012-02-29). "The Beauty of Shad Roe".

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