Twaite Shad
Twaite shad are anadromous members of the herring family that spend most of their lives at sea before pushing into estuaries and rivers each spring to spawn. Once common across British rivers, populations collapsed due to weirs, pollution and overfishing.
Today they are fully protected in the UK — no targeting, retaining or deliberate disturbance is permitted — but anglers fishing estuaries for bass, mullet or sea trout may encounter them as accidental bycatch.
Scientific Name: Alosa fallax
Also known as May fish, twaite
- Herring-shaped body with a bluish-green back, silvery flanks and a sharp, keel-like belly edge; adult fish typically 25–40 cm.
- Most reliable field mark: a row of 6–10 large dark spots running behind the gill cover along the upper flank — these can fade quickly after death.
- Gill cover is ridged with radiating lines; tail deeply forked with large plate-like scales at the base.
- Easily confused with allis shad — the twaite has fewer gill-rakers (40–60 vs 90–130) and more anal fin rays (19–23 vs 25–26 on allis); spot count alone is not definitive.
What to know
Habitat Distribution
- Native to UK coastal and estuarine waters; spends the majority of its adult life at sea before entering rivers to spawn.
- Strongest remaining UK populations are associated with the River Severn, River Wye and River Usk systems in the west; also recorded in the Solway Estuary in Scotland and estuaries of the Tamar, Towy and Humber.
- Spawning takes place in the lower and middle river reaches over clean gravel and cobble substrates in well-oxygenated water; eggs are released into the water column and settle between stones.
- Weirs and other in-river barriers have historically cut off access to upstream spawning grounds; fish pass projects on the Severn have recently reopened stretches closed since the 1840s.
Key Locations
- River Severn — the most significant UK population; fish pass projects have recently reopened historic spawning grounds between Worcester and Stourport after nearly 180 years.
- River Wye and River Usk — both designated Special Areas of Conservation partly for their twaite shad populations; known spawning areas on shallow gravel near deeper holding pools.
- Solway Estuary, Scotland — the main Scottish location, though spawning sites here are not well documented.
- Estuaries of the Tamar, Towy and Humber — recorded shad presence during spring migration runs, where bycatch encounters are most likely.
Specific Spots
- During spawning runs, fish congregate in deeper holding pools adjacent to shallow gravel runs — the shallows are where spawning happens at night, the pools are where fish rest by day.
- Tidal reaches and estuary mouths concentrate fish as they stage before moving upriver; anglers targeting other species near these areas are most likely to encounter shad as bycatch.
- Near weirs and fish passes, fish can stack up waiting for suitable water levels — these are known shad pinch-points on rivers like the Severn.
Twaite Shad FAQ
Answers from onWater's species guide.
What are the best lures and bait for Twaite Shad?
No lure or bait selection is relevant for deliberate targeting, it is illegal. Small silver spinners and shad-profile lures are the most common accidental triggers and should be avoided in known shad areas during spring runs.
What flies work for Twaite Shad?
No fly selection is relevant for deliberate targeting, it is illegal. Small wet flies and surface patterns fished in estuaries during spring can accidentally hook shad; anglers should be prepared to release any accidental capture immediately with minimal handling.
When is the best time to fish for Twaite Shad?
Spring (late April–June): spawning migration brings fish into estuaries and up rivers, the only time shad are present in freshwater and the period when accidental bycatch is most likely. Outside the spawning run, twaite shad are at sea and rarely encountered by UK anglers.
How do you catch Twaite Shad?
Deliberately targeting twaite shad is illegal in the UK. Anglers most commonly encounter them as accidental bycatch while fishing estuaries and tidal river reaches for bass, mullet or sea trout during the spring spawning run, typically between late April and June.
What do Twaite Shad eat?
At sea, twaite shad feed on marine invertebrates, zooplankton and small fish; once they enter freshwater to spawn they largely stop digesting, though they will still strike at food through what appears to be instinct.
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