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.
Pelecus cultratus Pelecus cultratus Pelecus cultratus, known variously as the sichel, the ziege, the sabre carp or sabrefish, is a species of cyprinid fish from an Eastern Europe and adjacent Asian regions. It is the only species of its genus. This species inhabits lower reaches of rivers and brackish waters of eastern Baltic, Black, Caspian and Aral Sea basins. This fish has no major threats and the IUCN lists it as being of "Least Concern". The ziege resembles a large Baltic herring in appearance. It grows to about in length. It has a keel on its belly which from the side looks