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.
Fish as food "fiscas") which was pronounced as it is today. English also has the term seafood, which covers fish found in the seas and oceans as well as other marine life used as food. Over 32,000 species of fish have been described, making them the most diverse group of vertebrates. In addition, there are many species of shellfish. However, only a small number of species are commonly eaten by humans. Fish can be prepared in a variety of ways. It can be uncooked (raw) ("e.g.," sashimi). It can be cured by marinating ("e.g.," ceviche), pickling ("e.g.," pickled herring), or smoking ("e.g.," smoked