|Scientific Name:||Alosa alosa|
|Species Authority:||(Linnaeus, 1758)|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Freyhof, J. & Kottelat, M.|
|Reviewer/s:||Bogutskaya, N., & Smith, K. (IUCN Freshwater Biodiversity Unit)|
Presently only very locally distributed outside France. In the past it has been a victim of pollution, impoundment of large rivers and overfishing throughout Europe. However, most populations declined during first decades of 20th century and it now seems to have stabilised at a low or medium level in recent times.
|Range Description:||Baltic, North and western Mediterranean Seas, Atlantic coast of Great Britain, Ireland, France, Spain, Portugal and Morocco from where adults ascend rivers, migrating far upstream to spawn. Earlier ascended Rhine for about 850 km up to Basel (Switzerland). Now, nearly extirpated east of Rhine, most abundant in Loire and Garonne drainages (France). Landlocked populations in some man-made lakes in Morocco and Portugal.|
Native:Belgium; Denmark; France; Germany; Gibraltar; Guernsey; Iceland; Ireland; Isle of Man; Jersey; Lithuania; Morocco; Netherlands; Norway; Poland; Portugal; Russian Federation; Spain; Sweden; United Kingdom
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Currently large populations in France. Has declined outside France, mainly in the early 1900s, almost extirpated in Germany due to pollution in the 1920's (Freyhof pers comm.).|
|Habitat and Ecology:||
At sea, pelagic, in deep water down to 300 m. Juveniles remain close to shore and to estuaries. Migrates from sea upriver, spawning in main river or entering large and warm tributaries. Spawning sites often situated near a confluence.
Anadromous. Males migrate upriver at 3-9 years. Females first reproduce 1-3 years later than males. Adults start approaching coasts at end of February and enter rivers when temperatures reach 10-12°C, usually in May. Spawning commences when temperature reaches 15°C. Optimal temperatures 22-24°C. Spawns in large, very noisy schools near surface at night. Eggs sink to bottom. Spent fish migrate back to sea, but most die after reproduction, having mated only once. Most juveniles migrate to river mouth during first summer and remain at sea until they mature. Individual fish are thought to return to their natal spawning site. At sea, feeds predominantly on plankton. In freshwater, adults do not feed and juveniles prey on insect larvae.
|Major Threat(s):||Overfishing, pollution and dam constructions (cutting off access to spawning sites). Gravel extraction in France is a current threat to the species.|
|Conservation Actions:||Fish passes and elevators in France allow access to spawning sites. It is a (EU - Berne Convention) Natura 2000 species, requiring protection from range states.|
|Citation:||Freyhof, J. & Kottelat, M. 2008. Alosa alosa. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 March 2014.|
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