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Alosa fallax

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII CLUPEIFORMES CLUPEIDAE

Scientific Name: Alosa fallax
Species Authority: (Lacepède, 1803)
Common Name(s):
English Twaite Shad, Twait Shad
Synonym(s):
Clupea fallax Lacepède, 1803

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-01-01
Assessor(s): Freyhof, J. & Kottelat, M.
Reviewer(s): Bogutskaya, N., & Smith, K. (IUCN Freshwater Biodiversity Unit)
Justification:
Now only very locally distributed (large estuaries), a victim of pollution and impoundment of large rivers throughout Europe. Most populations declined during first decades of 20th century. Current status of the species is good and is increasing in the North Sea and Baltic.
History:
1996 Data Deficient (Baillie and Groombridge 1996)
1996 Data Deficient

Geographic Range [top]

Range Description: Southern shore of Baltic, North Sea northward to Bergen, Atlantic coasts from Scotland and Ireland to Morocco, northern Mediterranean (and Nile) and rarely in northern Black Sea occasionally east to Crimea, from where adults ascend rivers, migrating a short distance upstream to spawn. Ascended Drin to Lake Ohrid. Earlier ascended Rhône for 600 km.
Countries:
Native:
Albania; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; Denmark; Egypt; France; Georgia; Germany; Gibraltar; Greece; Guernsey; Ireland; Israel; Italy; Jersey; Latvia; Lebanon; Lithuania; Monaco; Montenegro; Morocco; Netherlands; Norway; Palestinian Territory, Occupied; Poland; Portugal; Romania; Russian Federation; Serbia (Serbia); Spain; Sweden; Switzerland; Syrian Arab Republic; Turkey; Ukraine; United Kingdom
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Quite common in north sea basins and French Atlantic coast. Populations increasing in the Baltic
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Habitat:
At sea, pelagic. Juveniles remain close to shore and estuaries. Migrates from sea to rivers, spawns in main river often only few kilometres above limit of brackish water. Spawning also reported from small rivers over gravel bottom.

Biology:
Anadromous. Males migrate upriver at 2-3 years, females at 3-4. Many individuals spawn 3-4 seasons. Adults congregate near estuaries in April and enter rivers when temperatures reach 10-12°C, mainly in May-June. Spawning starts when temperature reaches about 15°C or more, in May-June. Spawns in large, very noisy schools near surface after midnight. Eggs sink to bottom or are pelagic. Spent fish migrate back to sea. Most juveniles migrate to river mouth during first summer and move to sea at end of second year, where most shads remain until they mature. Individual fish are thought to return to their natal spawning site. At sea, feeds predominantly on crustaceans and small fishes. In freshwater, adults do not feed. Juveniles prey on planktonic crustaceans.
Systems: Freshwater

Threats [top]

Major Threat(s): Dams blocking spawning sites, pollution.

Conservation Actions [top]

Conservation Actions: It is a (EU - Berne Convention) Natura 2000 species, requiring protection from range states.

Citation: Freyhof, J. & Kottelat, M. 2008. Alosa fallax. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 20 August 2014.
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