COLORADO SQUAWFISH Ptychocheilus lucius (Girard, 1856) 



Order: CYPRINIFORMES Family: CYPRINIDAE 



Distinguishing characteristics : Body slender, dusky-greenish above, sides silvery, 

 belly yellowish to whitish; long, slender, depressed head, caudal peduncle stout, lateral 

 line decurved, eye small, pharyngeal teeth 2, 5-4, 2; dorsal and anal fin rays 9. 



Present distribution : Middle and lower Green River, main Colorado River above Lake 

 Powell , and Salt River . 



Former distribution : Widely distributed in the Colorado River and major tributaries . 



Status : Seriously depleted . 



Estimated numbers : Unknown . 



Fecundity : Natural reproduction is known to occur only in the Yampa River and the 

 Green River below the mouth of the Yampa down to the confluence of the Colorado River. 



Reasons for decline : Modification of habitat by man through construction of large 

 reservoirs . The species will not reproduce in cold tailwaters below high dams nor in 

 reservoirs behind these dams. The species is adapted to life in turbid, swift, warm 

 rivers. Introduced fishes may have a decimating effect in waters not affected by dams. 



Measures proposed : No water developments should be made on the Yampa River upstream 

 from Dinosaur National Monument which would lower the stream temperature to that below 

 the levels required for reproduction of the species . Studies on ecological and reproductive 

 requirements should be continued. 



Number in captivity : Unknown . 



Breeding potential in captivity : Unknown . 



Remarks : The very specialized ecological requirements for spawning and successful 

 natural reproduction are the major factors contributing to the reduction in numbers of 

 this species . 



References: 



Girard, C. 1856. Researches upon the cyprinoid fishes inhabiting the fresh waters of 

 the United States of America, west of the Mississippi Valley, from specimens 

 of the Smithsonian Institution. Acad. Nat. Sci. Phila. Proc . 8 (1856), p. 165-213. 



Miller, R. R. 1961. Man and the changing fish fauna of the American Southwest. 

 Pap. Mich. Acad. Sci. Arts and Letters. Vol. 46, (1960), p. 365-404. 



Vanicek, C. D. and R. H. Kramer. 1969. Life history of the Colorado squawfish, 

 Ptychocheilus lucius, and the Colorado Chub, Gila robusta, in the Green River 

 in Dinosaur National Monument, 1964-1966, Trans. Amer. Fish. Soc . Vol. 98. 

 No. 2. p. 193-208. 



Vanicek, C. D., R. H. Kramer and the late D. R. Franklin. 1970. Distribution of 



Green River fishes in Utah and Colorado following closure of Flaming Gowge Dam. 

 Southwest. Nat. Vol. 14, No. 3, p. 297-315. 



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