Alosa vistonica Alosa vistonica Alosa vistonica is a species of shad, a freshwater fish in the Clupeidae family. It is endemic to a single shallow lake, Lake Vistonida in Greece. It is classified as critically endangered (CR) and is threatened by sewage, industrial effluents, destruction of spawning sites by agricultural development and increased salinity following the opening of a canal into the sea. It has been suspected to be extinct already. "A. vistonica" reaches a maximum length of 17 cm (SL). It is distinguished from other members of its genus entering freshwater of the Mediterranean basin by having 78-97 gill rakers and
Mattapoisett River mill purposes" and featured three herring weirs; the "Upper Herring Weir" in Rochester, the "Middle Weir" or "Church's Weir", and the "Lower Herring Weir" at the entrance to Mattapoisett Harbor. Fish populations drastically declined during the twentieth century until they were almost extinguished, but local restoration efforts from the 1980s onwards have fostered a slow recovery. The principal restoration tactic has been to remove snags and other obstacles from the river that serve to impede fish migrations. The Lower Herring Weir is one of the few rivers emptying into Buzzards Bay that has electronic fish counters installed. Reports from Alewives