Alosa to detect ultrasound (at frequencies above 20 kHz, which is the limit of human hearing). This was first discovered by fisheries biologists studying a type of shad known as blueback herring, and was later verified in laboratory studies of hearing in American shad. This ability is thought to help them avoid dolphins that find prey using echolocation. "Alosa" species are generally pelagic. They are mostly anadromous or semianadromous with the exception of strictly freshwater landlocked species. "Alosa" species are generally migratory and schooling fish. Males usually mature about a year before females; they spawn in the late spring to summer.
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