Alosidae

Allis shad

Alosa alosa

Coastal shoals pressing far upstream into great rivers

• Gray
• Silver
• Temperate
• Coastal
• Nearshore
• Globally widespread
• Marine fish
• Fusiform
• Compressed cross-section
• Large
• Temperate fish

Steeped in riverine folklore and commanding vital ecological roles along western European coastlines, the allis shad is a large, deep-bodied anadromous clupeoid renowned for its migratory stamina. Its laterally compressed, shimmering silver body displays a dark blue-green dorsal surface that reflects iridescent emerald highlights under sunlight, broken behind the gill cover by a conspicuous, dark circular shoulder blotch occasionally trailed by smaller dots. The upper jaw features a distinct central notch that accommodates the tip of the lower jaw, while the gill arches house over ninety fine, comb-like gill rakers used to strain microplankton. Distributed along the eastern Atlantic Ocean from Norway and the British Isles to Portugal and Morocco, adults spend several years schooling in coastal shelf waters down to one hundred meters depth, feeding on mysids and small shrimps. In late spring, mature shoals ascend large pristine rivers like the Loire and Gironde, gathering at night over gravel shallows to spawn in vigorous surface circles. Maximum recorded length attains eighty-three centimetres.

Sources: FishBase & MBA — Allis Shad, Alosa alosa