The Severn’s Silver Spring Passage
Gloucester’s Twaite Shad Run
In May, the tidal River Severn near Gloucester briefly fills with one of Britain’s most elusive migratory fish: the twaite shad. Silver-sided and herring-shaped, it arrives on the flood tide, moving through the split channels towards gravel where spawning can take place. The run is short, powerful and highly mobile, a sharp remnant of the vast spring migrations once recorded on the river.
Tide, Weirs and Moving Water
The Gloucester passage is shaped by two channels and two major weirs. Maisemore controls the western route, while Llanthony stands on the eastern channel. On a strong rising tide, shad can gain the depth needed to clear these structures, then press upstream as the current slackens near the crest. The key is movement in the water, not simply a high river level.
For an angler studying the Severn, the most revealing places are the tidal reaches around Maisemore, the channels through Gloucester and the river downstream towards Tewkesbury. Haw Bridge, below the town, sits within a stretch where spawning activity has been recorded. A pair of binoculars is often more useful than a cast: the fish may appear as quick silver flashes in the flow before disappearing on the ebb.
Clean gravel is central to the story. Shad scatter their eggs across mobile stones rather than soft silt, making the gravel belt below Diglis and near the Teme confluence an important nursery landscape. After spawning, adults drift back downriver, leaving only disturbed stones, fading rings and a few bright scales on the shallows. At dusk, the Severn’s tide turns beneath Gloucester’s bridges, and the brief silver passage begins again.