The salmons group is a relatively small group of fish, but with enormous economic and cultural importance to humans. There are 66 species in one family. All salmons and trout are originally from the northern hemisphere, although they have been introduced throughout the world for food and sport fishing. Many salmon species have a life cycle with both freshwater and marine stages: they are born in freshwater rivers and migrate to the oceans to grow, then migrate back to the freshwater rivers where they hatched to reproduce. Salmons are very popular food fish and are widely fished commercially and for sport.