twaite shad
Alosa fallax
Conservation status data sourced from the IUCN Red List of Threatened Species.
36
Countries
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Twait_shad
Taxonomy & Classification
Kingdom
Animalia
Phylum
Chordata
Order
Clupeiformes
Family
Clupeidae
Genus
Alosa
twaite shad belongs to the family Clupeidae, order Clupeiformes, within the unknown class.
Species Profile
Species profile data sourced from the IUCN Red List of Threatened Species.
The twaite shad faces severe population declines across its range due to habitat degradation and barriers to migration. Dam construction and river modifications have blocked access to critical spawning grounds, while water pollution and overfishing have further reduced populations to critically low levels.
Key Facts
Habitat & Distribution
Anadromous fish inhabiting coastal marine waters, estuaries, and lower reaches of rivers along the Atlantic coasts of Europe and North Africa. Adults migrate upstream to spawn in freshwater rivers, typically in areas with gravel substrates and moderate currents.
Threats
IUCN Red List: Critically Endangered
The twaite shad faces severe population declines across its range due to habitat degradation and barriers to migration. Dam construction and river modifications have blocked access to critical spawning grounds, while water pollution and overfishing have further reduced populations to critically low levels.
Habitat degradation in spawning rivers
Overfishing and bycatch in commercial fisheries
River barriers and dam construction blocking spawning migration
Water pollution and eutrophication in rivers and estuaries
Climate change affecting marine and freshwater environments
Found in 36 Countries
National vs Global Threat Status
How this species is assessed at the national level compared to its IUCN global status (CR).
| Country | National Status | Global Status | Comparison |
|---|---|---|---|
| EU | LCLeast Concern | CRCritically Endangered | Lower local risk |
| EU | LCLeast Concern | CRCritically Endangered | Lower local risk |
National Red List data sourced from the National Red List Project (nationalredlist.org, ZSL) and country-specific Red List authorities.
Community Sightings
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Sources & Attribution
How to Cite
IUCN: IUCN (2025). The IUCN Red List of Threatened Species. Version 2025-1. Available at: https://www.iucnredlist.org. doi:10.2305/IUCN.UK.2025-1.RLTS
GBIF: GBIF.org (2025). GBIF Home Page. Available at: https://www.gbif.org
National Red Lists: ZSL (2025). National Red List. Zoological Society of London. Available at: https://www.nationalredlist.org
This page: SpeciesRadar (2025). twaite shad (Alosa fallax). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/twaite-shad