Many types of fish undertake migrations on a regular basis, on time scales ranging from daily to annual, and with distances ranging from a few meters to thousands of kilometers. The purpose usually relates to either feeding or breeding; in some cases the reason for migration is still unknown.
Migratory fishes are classified according to the following scheme:
- diadromous fishes travel between salt and fresh water. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two (Greek: 'Dia' is between) There are three types of diadromous fish:
- anadromous fishes live in the sea mostly, breed in fresh water (Greek: 'Ana' is up; The noun is "anadromy")
- catadromous fishes live in fresh water, breed in the sea (Greek: 'Cata' is down)
- amphidromous fishes move between fresh and salt water during some part of life cycle, but not for breeding (Greek: 'Amphi' is both)
- potamodromous fishes migrate within fresh water only. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly (Greek: 'Potamos' is river)
- oceanodromous fishes migrate within salt water only. (Greek: 'Oceanos' is ocean)
One of the best-known anadromous fish are the five species of Pacific salmon, which are Chinook (King), Coho (Silver), Sockeye (Red), Chum (Dog) and Pink (Humpback). Oncorhynchus is a Genus of in the family Salmonidae; it contains the Pacific Salmons and Pacific Trouts They hatch in small freshwater streams, go down to the sea and live there for two to six years, most staying in the ocean for around four years, then return to the same streams where they were hatched, spawn, and die shortly thereafter to feed fauna and replenish the earth. Salmon are capable of going hundreds of kilometers upriver, and humans must install fish ladders in dams to enable the salmon to get past. Fishways, most commonly called fish ladders but also known as fish passes and in Australia also referred to as fish steps, are structures on or around artificial A dam is a barrier that divides waters. Dams generally serve the primary purpose of retaining water while other structures such as Floodgates, Levees Other examples of anadromous fishes are sea trout, three-spined stickleback, and shad. The brown trout ( Salmo trutta morpha fario and S trutta morpha lacustris) and the sea trout ( S The three-spined stickleback, Gasterosteus aculeatus, is a Fish native to much of northern Europe, northern Asia and North America The shads or river herrings comprise the Genus Alosa, Fishes related to Herring in the family Clupeidae
The most remarkable catadromous fishes are freshwater eels of genus Anguilla, whose larvae drift on the open ocean, sometimes for months or years, before travelling thousands of kilometres back to their original streams (see eel life history). True eels ( Anguilliformes) are an order of Fish, which consists of four suborders 19 families 110 Genera and approximately 600 Anguillidae is a family of fishes that contains many of the freshwater eels. The Eel is a long thin bony fish of the order Anguilliformes.
An example of an amphidromous species included the Bull sharks living in Lake Nicaragua of Central America and in the Zambezi river of Africa. The bull shark, Carcharhinus leucas, also known as the bull whaler, Zambezi shark or unofficially known as Zambi in Africa and Nicaragua Both the aforementioned lake and river are fresh water, yet Bull sharks (a known man eater, and very aggressive shark) will live and feed in these waters as well as migrating to and from the sea (the Indian Ocean in the case of the Zambezi Bull shark and the Altantic Ocean in the case of the Lake Nicaragua Bull shark).
Diel vertical migration is a common behavior; many marine species move to the surface at night to feed, then return to the depths during daytime. Diel vertical migration refers to a pattern of movement that some Organisms living in the Ocean 's Photic zone undertake each day
A number of large marine fishes, such as the tuna, migrate north and south annually, following temperature variations in the ocean. Tuna, are several Species of ocean-dwelling Fish in the family Scombridae, mostly in the genus Thunnus. These are of great importance to fisheries. For the fishing industry and the practice of fishing see Fishing.
Freshwater fish migrations are usually shorter, typically from lake to stream or vice versa, for spawning purposes.
See also
- DSSAM Model
- Fish ladder
- Hydrology transport model
- Ocean Tracking Network
- Salinity
- Stenohaline
- Euryhaline
References
- Carl E. The DSSAM Model (Dynamic Stream Simulation and AssessmentModel is a Computer simulation developed for the Truckee River to analyze water quality Fishways, most commonly called fish ladders but also known as fish passes and in Australia also referred to as fish steps, are structures on or around artificial An hydrological transport model is a Mathematical model used to simulate river or Stream flow and calculate water quality parameters The Ocean Tracking Network is a research effort using implanted acoustic transmitters to study fish migration patterns Salinity is the Saltiness or dissolved salt content of a body of Water. Stenohaline describes an organism usually Fish, that cannot handle a wide fluctuation in the Salt content of Water. Euryhaline organisms are able to adapt to a wide range of salinities Bond, Biology of Fishes, 2nd ed. (Saunders, 1996), pp. 599-605.
- Michael Blumm, J. D. , Sacrificing the Salmon: A Legal and Policy History of the Decline of Columbia Basin Salmon, Bookworld Publications, 2002.
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