British Wildlife Wiki

The Allis Shad (Alosa alosa) is a species of fish in the Clupeidae family.


It is found in most of Europe and northwestern Africa.

Biology and Life-cycle[]

Alosa alosa has a similar lifecycle to Alosa fallax. They are known to live in sympatry with Alosa fallax. Some studies have suggested that the Alosa fallax and Alosa alosa species can hybridize. They are anadromous species just like many other species in the Alosa genus. However, there is some record of them being landlocked, suggesting an ability to adapt well to their environment. They primarily live at sea on feeding grounds and will migrate to their spawning grounds between April and June once they are sexually mature. Maturity usually ranges from 3-7 years of age.[1]Alosa alosa can usually only reproduce once in their lifetime. It is observed that juvenilles appear in estruaries, brackish water, around July to August. The salinity of brackish water may impose problems to the juveniles migrating from freshwater.

Population Reduction[]

Populations have been reduced primarily by overfishing, pollution, and habitat destruction. Hybridization between species is more likely with species affected by human disturbances. It is estimated that the estruarine phase, or the time that they are in the estruaries migrating from spawning grounds to sea, has a duration in Alosa alosa of up to six months. The estimate however does not take into account individual variation and/or survival of juveniles in the estruarine phase.


Four special areas of conservation have been designated in Ireland where Alosa species have been known to spawn. Alosa alosa "has been placed in Appendix III of the Bern Convention (1979) that lists protected fauna species as well as in Appendix II and V of the European Community Habitats Directive (1992) that list, respectively, species whose conservation requires the designation of special areas of conservation and that are subject to management measures.” However, Alosa alosa are currently under a moratorium (2008) in numerous French watersheds.