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
Herring to dwell in deeper waters. Predators of herring include seabirds, marine mammals such as dolphins, porpoises, whales, seals, and sea lions, predatory fish such as sharks, billfish, tuna, salmon, striped bass, cod, and halibut. Fishermen also catch and eat herring. The predators often cooperate in groups, using different techniques to panic or herd a school of herring into a tight bait ball. Different predators species then use different techniques to pick the fish off in the bait ball. The sailfish raises its sail to make it appear much larger. Swordfish charge at high speed through the bait balls, slashing with