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 scad little importance to fisheries, taken occasionally on hook and line gear. Herring scad The herring scad ("Alepes vari") (also known as the duskyfin crevalle and trevally scad), is a common species of tropical marine fish in the jack family Carangidae. The species inhabits the surface waters of coastal regions throughout the Indo-West Pacific region, feeding on a variety of crustaceans and small fishes. It is the largest fish of the scad genus "Alepes", growing to a recorded length of 56 cm. The herring scad is identified among the genus "Alepes" by its more numerous and smaller scutes and the number