Cornish Biodiversity Network  -  Supporting Wildlife Recording

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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Alosa fallax - Twaite Shad

Habitat & Distribution

This fish is found in inshore waters, entering the rivers in spring when the water

temperature reaches 10-12\'baC, they penetrate upstream to spawn on stony ground, then returning immediately to the sea. It is distributed along the Atlantic coastline from Morocco to Iceland and is more common than the Allis Shad, but both species should now be considered as rare or very scarce. This species can be relatively common at times in the Falmouth Bay and Estuary area.


This species has been in decline since the mid-nineteenth century, due to interruption of its spawning migration resulting from obstructions along the various river courses. Deterioration of water quality as a result of agricultural and industrial pollution has also played a part. Numerous specimens are accidentally caught in nets, set for other fish species, in the open sea.


Listed under Appendix III of the Bern Convention; listed under Annex IIa and Va in the EC Habitats Directive; It was added to Schedule 5 of the Wildlife and Countryside Act (1981) in 1998, S.9 (4) (a) \endash 1998, damage/destruction of place of shelter/protection. It is also on the UK List of Priority Species and is an NIMF candidate species.


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.

Cornish Biodiversity Network. 2017.