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t68 The .Southurrs(rrn A'o(uralit! vol. 2t1, no. 2 concentration o[ salts. Hubbs (1960) found archaeological remains of young razorback suckers abou[ 82.5 km upstream from the Salton Sea in Fish Creek Cali(omia, indicating successful reproduction in that system during high lake stages. The species re-entered the Salton Sea when it re-filled in 1905-07 (Evermann, ]916), but disappeared with increasing salinity by 1929 (Cole- man, 1929). In the mainstream Gila River, razorback suckers occurred near Yuma (Evermann and Rutter, 1895), in the now-dry reach between Yuma and Gila Bend (Bartlett, 1854), in the Phoenix area where they were called "buffalo" or "bu[falofish" (Miller, ]961; Minckley, 1973), in archaeological sites near Casa Grande (Minckley, 1976), and almost to New Mexico (Kirsch, 1889; Chamberlain, 1904) (Fig. 1). They also ranged far upstream in the Verde River (Minckley and Alger, 1968; K'agner, 1959), to well above the present Roosevelt Lake on Tonto Creek (Hubbs and Miller, 1953) and the Salt River (Ellison, 1980), and to the upper San Pedro River (Miller, 1955, 1961). Razorback suckers remained locally abundant until recently. They were common in irrigation channels of the Palo Verde Valley, California, until the 1940s (Loudermilk, pers. comm.). In the early 1900s they were so com- mon in canals in the Phoenix area and in the Salt River above Roosevelt Lake that "wagon loads" were collected by local people (Miller, 196]; Elli- son; 1980). Carl L. Hubbs collected an adult in Roosevelt Lake in 1926 (UMMZ 94749, 71.5 cm TL). T. T. Fraizer, local resident, considered the species extirpated in Roosevelt Lake by 1950 (Hubbs and Miller, 1953; R. R. Miller, pers. comm.). As late as 1999 a commercial fishery [or razorback suckers that ranged to 6 kg individual weight existed in Saguaro Lake, cen- tral Arizona (Hubbs and Miller, 1953). In 1966 that reservoir was drained and none was present (Minckley and Deacon, 1968). The species persisted as adults in the Verde River until at least ]954 (Wagner, 1954), and in canals northeast o{ Mesa, Arizona, .to about that same time (Vardell Blau, Mesa, Arizona, pers. comm.). Young razorback suckers were last preserved from the Gila River drainage in 1926 (Hubbs and Miller, 1953; 5 specimens, 52-100 mm TL, UMMZ 94877). 7n the Colorado River mainstream, razorback suckers "were doing well" in the 1940s and early 1950s (Wallis, 1951; Jonez and Sumner, 1959). Large concentrations of spawning adults were observed in Lake Mohave and in the river below that reservoir (Douglas, 1952), and the species was considered common (Mo[te[t, 1942; Dill, 1944; Jonez et al., 1951; Wallis, 1951). Minckley and Deacon (1968) noted that no specimens shorter than about 90 cm TL had been caught from the lower Colorado River "in recent years," and this pattern o[ only large individuals being present has generally per- sisted to date. Few razorback suckers were taken or observed in Lake Mead in the 1970s (Anonymous, 1973), and McCall (1980) and Sue Morgenson (AGFD, pers. comm.) recorded only 18 large individuals (55.2 to 67.0 cm TL for 11 fish measured) while sampling that reservoir itt 1976-80. Between Davis Dam and Lake Havasu, 8 adult razorback suckers (54.5-68.0 cm TL for 7 fish measured) were recorded by CFGD in 1972-76. Lake Havasu popula- tions also are low (Guenther and Romero, 1973; Mike Donahoo, USFWS, pers. comm.); none was taken there or in the river below in a 1975-76 survey May 1988 Minckley-S~a~us of Razorback Sucker 169 by Minckley (1979). Downstream from Lake Havasu a 2.05 kg razorback sucker (not measured) was taken in 1969 near Blythe, California, an angler caught a 56.0 cm TL specimen in the Palo Verde Valley in 1976, and another ca. 60 cm fish was found dead there in 1977. Atrammel-net survey by Loudermilk (pers. comm.) from Parker to Morelos dams in 1980-81, spe- cifically for razorback suckers, caught none, but a small population persists in Senator Wash Reservoir, California. Two small individuals (32.7 and 37.1 cm TL) were caught from canals in the Blythe-Parker area in 1980 (Dona- ' hoo, in Anonymous, ]981), an adult was netted from Imperial Reservoir in March 1973 (ASU 6283), and five young fish (ca. 15 cm TL) were caught from the East Highline Canal and from commercial fish ponds filled from that canal near Niland, California, in 1973 and 1974 (St. Amant et al., 1974). Over the past 5 years, 1 or 2 individuals pet year have been reported by fishermen from [he Imperial-Coachella Valley irrigation system. The fish i remains common in Lake Mohave as large adults (Gustafson, 1975a-b), as will be detailed below. Young-of-the-year or juvenile razorback suckers were collected in 1950 from the Colorado Rivet from pools below Laguna Dam (2 individuals, 17 and 20 mm TL, UMMZ 162645), below Davis Dam (3 individuals, 80-135 mm TL, UMMZ 160730; Douglas, 1952), near Cottonwood Landing (6,100 specimens, 12-42 mm TL, UMMZ 162845 and ASU 3719), and in Lake Havasu (Douglas, 1952). Jonez and Sumner (1954) also identified young razorback suckers from below Davis Dam in 1950. One larva was caught by University of Nevada, Las Vegas (UA'LV), biologists below Hoover Dam in 1979 (ASU 8455), larvae have been collected in Senator Wash Reservoir, and from along the' shoreline o[ Lake Mohave in 1981 (Loudermilk, pers. comm.), and in plankton tows in Lake Mohave in 1982 (Larry Paulson, UNLV, pers. comm.). Fishes oJL¢ke Mohave.-Twenty-nine species of fishes have been reliably reported from Lake Mohave, of which only six are native (Table 1). Four o[ the six, speckled dace, Colorado squawfish, humpback chub, and ^annel- mouth sucker, have almost certainly been long extinct in the reservoir. Of introduced species, the Pacific salmons, goldfish, golden shiner, and fathead minnow also are rare or extirpated. Utah chub (Gila nlraria [Girard]) was reported below Lake Mead and in bait shops along the lower Colorado River by Jonez et al. (1951) and Miller (]952), but has yet to become esta- blished and is tentatively excluded. Other introduced fishes are both up- and ', downstream from the reservoir and are thus to be expected. Native fishes ', that occurred both north and south of the area and were thus at least tran- sient include roundtail chub (Gila robusta Baird and Girard) and woundfin (Plagoplerus argenlissimus Cope). Nel Calches.-Carp dominated catches in trammel nets in Lake Mohave (Table 2). They were relatively rare only in cold water below Lake Mead. In 1979, carp used nets as spawning substrate, and in May were so abundant that sampling was curtailed when catches exceeded an average of 40 carp per 100 m= o[ netting per day. Catfish and bass were relatively consistent in occurrence, but trout domi- nated only in cold water below Hoover Dam. Surface temperatures of Lake