7982 - Laserfiche WebLink

Home Browse Search

'I l( , 1): Chapter 19 Ecology and Management of Colorado Squawfish Harold M. T yus Introduction The Colorado squawfish (Ptychocheilus lucius) is the largest minnow (family Cyprini- dae) native to North America, reaching total ,lengths of 1.8 m and weights of 36 kg (R. R. Miller 1961). Popular names of "salmon," "white salmon," "whitefish" (Evermann and Rutter 1895), and "Colorado River salmon" (Measeles 1981) were applied to this attrac- tive species (Fig. 19-1), reflecting its large size, body shape, coloration in springtime, and mi- gratory nature. American Indians and early settlers knew about squawfish and used it for food (Minckley 1965, 1973; Seethaler 1978). Ichthyologists of the later nineteenth century documented its widespread distribution, and it was reponed common in'most larger rivers of the Colorado River system from Wyoming to ..... Mexico (Girard 1856; Evermann and Rutter i~,.1895; D. S. Jordan and Evermann 1896b, ..,J'1923; R. R. Miller 1961). :'.. Although squawfish were common in the lower Colorado River basin in Arizona and ,(;alifornia until the 193.0S (R. R. Miller ~961), records were few after then, and efforts ,to collect them there in the mid-1960s met with failure (Minckley 1973). By the early ',970S the species was essentially gone from "e"lower basin (Moyle 1976; Minckley ~985b). It fared better in the upper basin in CoI~rado and Utah (Fig. 19-2.) and now exists in largest numbers in the Green River sub- basin (Holden and Wick 1982; Tyus et aI. 1982a, 1987; Archer et aI. 1986). It was listed as an endangered species by the US. Bureau of Sport Fisheries and Wildlife (now US. Fish and Wildlife Service [USFWS]) in 1967 (Federal Register 32[43]:4001) and received protec- tion under the Endangered Species. Act (ESA) of 1973 (US.c. 1531, et seq.) in early 1974 (Federal Register 39[3]:1175). Historical information on the Colorado squawfish is largely taxonomic and distribu- tional, and little was known of its life history until the 1960s (R. R. Miller 1964a). Interest in extant populations increased at that time, and pre- and postimpoundment studies of Flaming Gorge Reservoir began under section 8 of the Colorado River Storage Project Act (Binns et aI. 1963). These studies, conducted by various governmental agencies (Bosley 1960; McDonald and Dotson 1960; Azevedo 1962.a, b, c; Binns 1967a, b) and graduate stu- dents at Colorado State and Utah State univer- sities (Banks 1964; Vanicek 1967; Holden 1968, 1973; Seethaler 1978), contributed much toward early understanding of the biol- ogy of squawfish and other endemic Colorado River fishes. The environmental movement, energy crisis, and water-development issues of the 1970S stimulated intensified research on rare and im- periled fishes. This was reflected by a sudden P79<64- i ~l ,j ,I If I if' !, !~ ~: R .'j ~ l H ~}! !,.~ i.IiJ.". i "Ii.' iii~:::i!:i:" 379