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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. Fish usually migrate to feed or to reproduce; in other cases the reasons are unknown. ==Classification== As with various other aspects of fish life, zoologists have developed empirical classifications for fish migrations. Two terms in particular have been in long-standing wide usage: * Anadromous fishes migrate from the sea up (Greek: ἀνά 'ana', up and δρόμος 'dromos', course) into fresh water to spawn, examples - Salmon, Striped Bass.〔Moyle, P.B. 2004. Fishes: An Introduction to Ichthyology. Pearson Benjamin Cummings, San Francisco, CA.〕 * Catadromous fishes migrate from fresh water down (Greek: κατά 'kata', down and δρόμος 'dromos', course) into the sea to spawn.〔Moyle, P.B. 2004. Fishes: An Introduction to Ichthyology. Pearson Benjamin Cummings, San Francisco, CA.〕 Tyus, H.M. 2012. Ecology and conservation of fishes. Taylor and Francis Group, CRC Press, Boca Raton, London, New York. In a 1949 journal article, George S. Myers coined the inclusive term ''diadromous'' to refer to all fishes that migrate between the sea and fresh water. Like the two well known terms, it was formed from classical Greek ((), "through"; and (), "running"). ''Diadromous'' proved a useful word, but terms proposed by Myers for other types of diadromous fishes did not catch on. These included ''amphidromous'' (fishes that migrate from fresh water to the seas, or vice versa, but not for the purpose of breeding), ''potamodromous'' (fishes whose migrations occur wholly within fresh water), and ''oceanodromous'' (fishes that live and migrate wholly in the sea).〔 Although these classifications were originated for fishes, they are, in principle, applicable to any aquatic organism. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fish migration」の詳細全文を読む スポンサード リンク
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