Shad

Twaite shad are anadromous fish, spending most of their adult lives in coastal marine waters before migrating into freshwater rivers to spawn. Members of the herring family, they are silvery, laterally compressed fish typically marked with a row of dark spots along the flank behind the gill cover. They form schools and feed on plankton and small fish, while serving as prey for larger fish, seabirds, and marine mammals, linking marine and freshwater food webs during their migratory movements.

The species has a wide range spanning the eastern Atlantic, Mediterranean, and connected river systems, with populations recorded across much of Europe, North Africa, and parts of North America, including the United Kingdom, France, Spain, Portugal, Germany, Italy, Morocco, Tunisia, and Canada, among many others. It inhabits both marine coastal waters and freshwater rivers and estuaries used for spawning.

No reliable population trend data currently exists, though the species is classified as Critically Endangered. Its decline stems from dam and weir construction that blocks access to historic spawning grounds, pollution and eutrophication degrading river and estuarine water quality, overfishing and incidental bycatch in commercial fisheries, and physical habitat degradation of spawning rivers through dredging and channelization. Climate change is an additional and growing pressure on both its marine and freshwater habitats.

Conservation responses include river restoration projects, construction of fish passes to restore access to spawning habitat, water quality improvement programs in some watersheds, and fishing regulations in parts of its range. Enforcement and habitat restoration remain uneven across the many countries it inhabits. Given the ongoing, multiple, and unresolved pressures acting simultaneously on both its marine and freshwater life stages, the species' overall outlook remains precarious without substantially expanded and coordinated international action.

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.