fish migration

Many species of salmon are anadromous and can migrate long distances up rivers to spawn Allowing fish and other migratory animals to travel the rivers can help maintain healthy fish populations

Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.