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:Jth ,in ,jle ','ar ,Ih wt !ck ,re :of le- ,-a] .In "'r~ ig- .re ,10 ':'f, 'IS ,n ,j" 15 '1- i.~ m \e '0 :e ,} ":g i\ r "1. [II \. '. .r '.1 ,I I HOLDEN AND STALNAKER--COLORADO RIVER FISHES 227 1892-93 or 1906. It apparently became es- tablished throughout the Colorado River system in the early 1900's, as many older fishermen believed it to be a native speCIes. Black bullhead-Ictalurus melas Rafinesque. The black bullhead is rare in the upper and lower sections of the study area, but more abundant in the slower water of Canyonlands National Park. It was collected exclusively in stagnant water areas, and usually only one or two indi- viduals were taken in anyone sample. Ellis (1914) reported that the species was successfully raised in ponds near Montrose and Grand Junction, Colorado. Thus, an early introduction into the river was possi- ble. C yprinodontidae Rio Grande killifish-Fundulus zcbrinus Jordan and Gilbert. The introduced Rio Grande killifish was collected only from the Colorado River and its tributary, the Gunnison River. It was not eommon; sel- dom were more than one or two taken in an area. The killifish was reported in Glen Canyon in 1954 and 1958 by Smith (1959) and in 1959 by McDonald and Dotson (1960). Miller and Lowe (1964) reported that this species was inadvertently intro- duced into Little Colorado River in 1938. It may have spread upstream from this poiqt but more likely was introduced separately illto the upper basin as a baitfish. Centrarchidae Largemouth bass-Micropterus salmoides LacCpede. The introduced largemouth hass is common only in area 6. Most of I hese fish are assumed upstream migrants from Lake Powell. The largemouth is rare in the remainder of the Colorado River to Grand Junction. Juvenile bass, age group I, were most commonly found. Spawning may occur in ponded areas along the river in area 8 and perhaps also area 6. Olle adult bass was collected in area 2 i,! 1970, one ill area 4 in 1971, and one In .nea 11 in 1970. Largemouth bass were present in Glen Canyon in 1958 (McDonald and Dotson 1960), being originally stocked in Lake Mead in 1939 (Miller and Alcorn 1943). Bluegill-Lepomis macrochirus Rafin- esque. One adult bluegill was collected in area 2 in 1969. It may have originated from a pond either in upper Yampa drain- age or Duchesne River system. Bluegill are in Lake Powell but were not collected in the Canyonlands National Park area. Green sunfish-Lepomis cyanellus Rafinesque. Green sunfish were collected throughout the study area except in areas 1, 9, 11, and 12. They were almost exclu- sively taken in quiet, backwater areas. In the Green River system they are rare. Hundreds of young of the year were found in a small, drying cutoff pool in Desolation Canyon in 1969. Green sunfish are com- mOil in Colorado River. Apparently the slower water of the Colorado offers better habitat for this species than the Green River. Green sunfish were collected in the lower Colorado basin in 1926 (Miller and Lowe 1964). Wallis (1951) suggested that this species was inadvertently planted in Lake Mead in 1937. McDonald and Dotson (1960) reported green sunfish to be abun- dant in Glen Canyon. R. R. Miller (per- sonal communication) collected it in area 12 in 1968. It is not known whether this species moved up the Colorado River to the upper basin or was separately intro- duced. Percidae Walleye-Stizostedion vitreum Mitchill. Walleyes were taken occasionally in area 2, one in 1969 and four in 1970. They are somewhat more common at Ouray; three were collected in one week in March, 1969. The suspected source of these fish is the Duchesne River system, where walleye were stocked in a small reservoir. Cottidae Mottled scu1pin-Cottus bairdi Girard. Mottled sculpin were collected only at Echo Park. Being a cool water species, it i~