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Last modified
7/14/2009 5:01:44 PM
Creation date
5/20/2009 5:10:20 PM
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UCREFRP
UCREFRP Catalog Number
7147
Author
Holden, P. B. and C. B. Stalnaker
Title
Distribution and Abundance of Mainstream Fishes of the Middle and Upper Colorado River Basins, 1967-1973
USFW Year
1975
USFW - Doc Type
Transactions of the American Fisheries Society
Copyright Material
YES
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<br />l <br />t ~ <br /> <br />[. TRANSACTIONS of the <br />AMERICAN <br />FISHERIES SOCIETY <br /> <br /> <br />, . -k~-L/~ /}/1 ~ s~~ <br />,/ ,IV I q~5b' <br /> <br />~ <br />()1147_ <br /> <br />April 1975 <br /> <br />VOLUME 104 <br />NUMBER 2 <br /> <br />Distribution and Abundance <br />of Mainstream Fishes of the Middle and Upper <br />Colorado River Basins, 1967-1973 <br /> <br />PAUL B. HOLDEN AND CLAIR B. STALNAKER <br /> <br />Utah Cooperative Fishery Unit <br />Logan, Utah <br /> <br />ABSTRACT <br /> <br />Twellty-nine species of fishes were collected in the middle and upper C"lorano River basins <br />in 1967-1973. The native sllckcn;, Catostornus lotipinnis and C. discobolus, wcre the d')lIlinant <br />spccies in the study area. Introduced species oUlnumbered native specie" 19 to J.D. The intro- <br />duced hta/ums [lllllctatus and Notropis lutre"sis were abulldant throngboul most of the upper <br />basin. The abundance of introduced species has incH",sed steadily since 1900 as has the intro- <br />ductions of new species. Four endemic species, Ptychocheilus lucius, Gila dc'gans, Gila cypha, <br />and Xyrauchen texanus, are considered endangered. These rare forms reproduce in the lower <br />Yampa River, Desolation Canyon of middle Green River, and the lower Green River in Canyon- <br />lands National Park. The major reasons for the dedine of native fi"hes arc considered to be <br />alterations of habitat by high darns and introductiolls of exotic: speeies. <br /> <br />The native fishes of the Colorado River <br />basin comprise a unique fish fauna in <br />North America. Miller (1959) detcrmined <br />that 74('10 of native Colorado River basin <br />fishes are endcmic. This high degree of <br />endemism is intcgrally tied to the geologic <br />history of the basin, which involved long <br />periods of isolation. The Colorado H.iver <br />bcgins as a cold, clear stream in the <br />Rocky Mountains, then plunges inlo a dry <br />desert where it has cut spectacular can- <br />yons. In its pristine state it was a warm, <br />turbirl, often violent river, given to sudden <br />and drastic changes in volume and <br />turbidity. Endemic fishes of this area can <br />he placed in two categories: small-stream <br />forms fOll!ld primarily in ,he lower basin, <br />and large-river forms found in the main <br />stream and larger tributaries throughout <br /> <br />J <br /> <br />the basin. Much of the Colorado system <br />today is composed of large reservoirs with <br />cold, clear tail waters. This, along with <br />water diversion, has had a pronounced ef- <br />fect on t he native fish fauna. Miller (1961) <br />and Minckley and Deacon (1968) docu- <br />mented the decrease in native fishes in the <br />lower basin. The large-river fishes are ex- <br />tremely rare, if not extinct, in the lower <br />basin below Lake Mohave (Minekley 1973). <br />Therefore, the upper and middle basins <br />provide the last extensive natural strong- <br />hold for these endemic fishes. This group ./: <br />includes Ptvchocheilus I/lr;/I~ (Colorado V . <br />squawfi~, Gila cypha (humpback chub), <br />Cila elegalls (honytail chub), Gila rou/l.sta <br />(roundtail chub), Catost0I1111S latipinnis <br />(flannclmoulh sucker), and Xyrauchen tex- <br />anlts (humpback sucker). <br /> <br />217 <br /> <br />'1-~ <br />
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