Twait shad Twait shad The twait shad or twaite shad ("Alosa fallax") is a species of fish in the family Clupeidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea and is an anadromous fish which lives in the sea but migrates into fresh water to spawn. In appearance it resembles an Atlantic herring but has a row of six to ten distinctive spots on its silvery flanks. They become mature when three or more years old and migrate to estuaries, later swimming up rivers to spawn. Populations of this fish have declined due to overfishing, pollution and habitat
Atlantic herring not considered to be an Arctic species. The small-sized herring in the inner parts of the Baltic Sea, which is also less fatty than the true Atlantic herring, is considered a distinct subspecies ("Clupea harengus membras") ("Baltic herring"), despite the lack of a distinctive genome. The Baltic herring has a specific name in many local languages (Swedish "strömming", Finnish "silakka", Estonian "räim", "silk", Livonian "siļk", Russian "салака", Polish "śledź bałtycki, sałaka", Latvian "reņģes", Lithuanian "strimelė") and is popularly and in cuisine considered distinct from herring. For example, the Swedish dish surströmming is made from Baltic herring. Herrings reach sexual maturity