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:om- The the :ers. few :udy Irea hed 't'nt ,~w- ,jue- .IOW aJ- !ult Ice 'ed III :do rel ,,1- 'x- If- 'ilt I~r .\ I', :il rn \1 ,f 'e .1 '. '0 " ~ HOLDEN AND ST ALNAKER--COLORADO RIVER FISHES 225 been ideal habitat for this species. Taba, Murphy, and Frost (1965) reported that the red shiner was very abundant near Moab, Utah, in 1962-63. Stone, Fields, and Miller (1965) reported that the red shiner "ex- ploded" in 1963 in Lake Powell. It is therefore doubtful whether this fish, not present in Glen Canyon in 1959, could be- come so abundant over 200 miles upstream by 1962, if it moved upriver from the lower Colorado basin. More probable is an intro- duction near Grand Junction, Colorado, in the late 1950's or early 1960's, with subse- quent downstream movement and more re- cent movement up the Green River. Sand shiner--Notropis stramineus Cope. The sand shiner was first reported from the upper Colorado basin by Holden and Stalnaker (1974). It was collected in 1971 in areas 7 and 8, also in the Dolores River. It was abundant and may spread much as the red sruner. Its numbers and distribu- tion suggest it had been present for several years, perhaps introduced as a uaitfish, as it is common in the South Platte River system of eastern Colorado. The sand shiner was inadvertently planted into the Little Colorado Rivcr in 1938 (Miller and Lowe 1964). Creek chub-Semotilus atromaclllatus Mitchill. Another introduced cyprinid is the creek chub. It was found only around Echo Park in areas 2 and 3. Vanicek, Kramer, and Franklin (1970) found it below Flaming Gorge Dam, collecting ouly 12 specimens in fOllr years. Most of these werc taken in the area between the Dam and the mouth of the Yampa River. Simon (1946) reported the creek chub's presence in the Little Snake River. Therefore it has been in the Green River system fo~ some time but apparently has not fonnd condi- tions favorable for maintaining large popu- lations. Catostomidae Flannelmollth sllcker-Catostomus lati- pinnis Baird and Girard. The Oannelmouth "'.\cker is by far the mosl abundant large native species. Wen over 6000 adults were (\lllected during the study (Table 2). Adults and young were caught in all study sec- tions. The species was least abundant in areas 5 and 6. They were collected in all habitat types, fast current, riffles, eddies, and stagnant backwaters. In area 12 they were collected only in tributary streams. In upper parts of the study area, flan- nelmouth suckers were usually dark brownish- green dorsally, yellowish or orange laterally, and white ventrally. In river sections of generally more turbid water and sand bottom, they were light tan on the back and silvery white on the sides and belly. Bluehead sucker-Catostomus discoholus Cope. The bluehead sucker is abundant in areas 1, 2, 3, 8, 9, and 10; common in 4, 7, and 12; and rare in 5 and 6. This dis- tribution corresponds to the relative amount of rocky substrate in the valious areas. The bluehead sucker was usually collected over rocky bottom and was com- mon in riffles. In the sandy bottom reaches of the study area it was collected only over the few rocky areas created by talus slopes extending into the river. Bluehead suckers were also common in clear, rocky tributary streams. Stream specimens seldom exceed 20 cm in total J'ength, whereas 25-30 cm spccimens are common in the main river. In area 12 they were collected only in tributaries, but were common in riffle habitats of the main stream in 1968 (J. E. Deacon, personal communication). The bluehead sucker is polymorphic in the Colorado River system with slender and dcep peduncled forms present. The slender peduncled type is thought to be adapted for swift-water areas (Miller 1946). Both forms were collected during the study, as were intermediate individuals. All types were collected together. Deep forms are most common in the upper, colder parts of the basin and slender forms most common in the middle sections, especially area 4. No difference in habitat preference was noted when they were collected together. Liule or no difference was noted ill the hl\storical distribution or abundance of this species (Jordan and Evermann 1896). ..;;r: