Salmon is the common name for several species of fish in the family Salmonidae. Other fish in the same family are called trout. The difference between salmon and trout is sometimes said to be that salmon migrate and trout are resident, and that salmon spawn once and trout spawn many times, though these distinctions are not always strictly true.[citation needed] Salmon live along the coasts of both the North Atlantic (the migratory species Salmo salar) and Pacific Oceans (half a dozen species of the genus Oncorhynchus), and have also been introduced into the Great Lakes of North America. Salmon are intensively produced in aquaculture in many parts of the world.
Typically, salmon are anadromous: they are born in fresh water, migrate to the ocean, then return to fresh water to reproduce. However, populations of several species are restricted to fresh water through their lives. Folklore has it that the fish return to the exact spot where they were born to spawn; tracking studies have shown this to be true, and this homing behavior has been shown to depend on olfactory memory.
