Fish migration
Fish migrate for feeding or spawning, often over vast distances.
Fish migration is the mass relocation of fish from one area or body of water to another, occurring on time scales from daily to annually and over distances from a few metres to thousands of kilometres. These movements are usually for better feeding or reproduction, though in some cases the reasons are unclear. Migrations involve schools of fish on a scale larger than normal daily activities and include anadromous (sea to fresh water to spawn) and catadromous (fresh water to sea to spawn) types.
- field
- Ichthyology, Marine Biology
- known_for
- Mass relocations of fish for feeding or spawning, including anadromous and catadromous migrations
- types
- Anadromous, Catadromous, Diadromous, Amphidromous, Potamodromous, Oceanodromous
- longest_freshwater_migration
- Dourada catfish, 5,500 km up the Amazon River
- notable_examples
- Salmon, striped bass, freshwater eels, bull shark, capelin, tuna
Lore & Background
Fish migration encompasses a variety of patterns. Anadromous fish, such as salmon and striped bass, live in the sea and migrate into fresh water to spawn. Catadromous fish, like freshwater eels, live in fresh water and migrate into salt water to spawn. The bull shark is a euryhaline species that moves freely between fresh and salt water. Many marine fish perform diel vertical migration, rising to the surface at night to feed and sinking by day. Tuna move north and south following temperature gradients. The dourada catfish makes the longest freshwater migration, traveling 5,500 km up the Amazon River.
Reader's Guide
Fish migration is significant for both ecological and economic reasons. Forage fish like capelin make large migrations between spawning, feeding, and nursery grounds, often in triangular patterns, which may help prevent cannibalism. The United Nations Convention on the Law of the Sea lists certain large pelagic fish as highly migratory species, which move in and out of exclusive economic zones and are treated differently under the treaty. These migrations are of great interest to the fishing industry. Dams increasingly disrupt traditional freshwater migrations, such as those of salmon swimming upriver to spawn. Zoologists have developed empirical classifications for fish migrations, including terms like diadromous, amphidromous, potamodromous, and oceanodromous, which can apply to any aquatic organism. The patterns of migration, influenced by ocean currents and food availability, remain a key area of study.
Did You Know?
- The dourada catfish travels 5,500 km up the Amazon River, the longest freshwater migration.
- Salmon and striped bass are well-known anadromous fish; freshwater eels are catadromous.
- The bull shark is a euryhaline species that moves at will from fresh to salt water.
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