Fish of the family Catostomidae, consisting of 11 genera and about 57 species, comprise a significant part of the fish fauna of Western North America. Life history information of some species is available (Bailey, 1969, and Brown and Graham, 1953, Catostomus catostomus; Dence, 1948, .f. commersoni; Douglas, 1952, Xyrauchen texanus; Geen et al., 1966, C. catostomus and C. coI!Dllersoni; Greenfield et al., 1970, .f. santannae; Harris, 1962, C. catostomus; Hauser, 1969,C. platyrhynchus; MacPhee, 1960, .f. macrocheilus; Nelson, 1968, .f.cotmnersoni and C. macrocheilus; Raney and Webster, 1942, C. commersoni; Smith, 1966, entire subgenus Pantosteus; Spoor, 1938, C. commersoni; Willsrud, 1966, C. tahoensis). Utah suckers, except those in Utah Lake, have received little attention (Frogley, 1950; Hatton, 1932; Lowder, 1951; Smith, 1966; Standing, 1954; Stubbs, 1966; Tanner, 1936). Reproductive studies of suckers have been limited to a description of spawning activities and estimates of fecundity (Geen, 1958, C. connnersoni C. catostomus and C. macrocheilus; Hauser, 1969, C. platyrhynchus; Mcswain and Gennings, 1972, Minytrema melanops; Wagner and Cooper, 1963, Erimyzon oblongus).