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American gizzard shad
The Gizzard shad (''Dorosoma cepedianum'') is a member of the herring family of fish, and is native to large swaths of fresh and brackish waters of the United States of America.〔Wuellner, M.R., Graeb, B.D.S., Ward, M.J., and Willis, D.W. (2009) Review of Gizzard Shad Population Dynamics at the Northwestern Edge of it's Range. ''American Fisheries Society Symposium'' 62: 37-653〕 The adult has a deep body, with a silvery-green coloration above fading to plain silver below.〔Miller, R.R. (1957) Origin and Dispersal of the Alewife, Alosa Pseudoharengus, and the Gizzard Shad, Dorosoma cepedianum, in the Great Lakes. ''Transactions of the American Fisheries Society'' 86: 97-111〕 The gizzard shad commonly resides in freshwater lakes, reservoirs, rivers, and streams but can reside in brackish waters, as it does on the Atlantic coast of the United States. Their range is across most of the continental United States, although they typically go no further north than New York and no further west than New Mexico.〔 They are large parts of many of the ecosystems they inhabit, and can drive changes in phyto- and zooplankton, thereby indirectly affecting other planktivorous fishes.〔Shepard, W.C. and Mills, E.L. (1996) Diel Feeding, Daily Food Intake, and Daphnia Consumption by Age-0 Gizzard Shad in Oneida Lake, New York. ''Transactions of the American Fisheries Society.'' 125: 411-421.〕 The gizzard shad has been widely used as a food source for game fish, with varied success in management and effectiveness.
== Physical description ==
The gizzard shad's dorsal fin starts behind the insertion of the pelvic fins, and the last ray is greatly lengthened in adults but not in the young. They have a long anal fin, with 25 to 36 long soft-rays on the fin. The mouth of the Gizzard shad has a short, wide upper jaw with a deep notch along the ventral margin, and a weak, relatively smaller lower jaw. The mouth itself is subterminal to inferior (on the lower portion of the head), and the adults possess no teeth.〔http://www.seagrant.wisc.edu/home/Default.aspx?tabid=605&FishID=56〕 The gizzard shad also has 90 to 275 gill rakers along the lower limbs.〔 Their ventral (pelvic) fins are in the thoracic position, or in the chest region of the fish. The gizzard shad can range from millimeter and milligram size when fry to a maximum recorded length of and maximum weight of .〔Williamson, K.L., and Nelson, P.C. (1985) Habitat suitability index models and in stream flow suitability curves: Gizzard Shad. ''U.S Fish and Wildlife Services Biological Reports.'' 82: 1-33〕 The average length is typically larger in northern waters, and ranges from mm at age three years to at age 10.〔 They have a highly reduced lateral line system, a feature shared by other members of the herring family.〔Stephens, R.R. (1985) The Lateral Line System of the Gizzard Shad, Dorosoma cepedianum Lesueur (Pisces: Clupeidae). ''Copeia.'' 1985: 540-556.〕 To compensate for this reduction in their mechanical sensory system, they have developed other methods of sensing movement.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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