Laserfiche WebLink
45 <br />Humback Chub (Gila c ha) <br />The humpback chub is an unusual fish uniquely adapted for life in the <br />torrential current of the large rivers of the Colorado River basin. It's <br />most prominant characteristic is a large nuchal hump rising abruptly from <br />behind the head. The size of the hump is variable, and it may overhang the <br />occiput in large adults. The caudal peduncle is thin, but not elongated as <br />found in the bonytail chub (G. elegans). The mouth is inferior and overhung <br />by a pronounced snout. Fins are large and falcate (Holden et al., 1974). <br />The humpback chub has never been abundant in the Colorado basin. It <br />was originally described from a single specimen collected from the Grand <br />Canyon (Miller, 1946). At one time its range apparently extended down the <br />Colorado River as far as the present site of Hoover Dam (Minckley, 1974). <br />It was also found throughout the upper system including the Green and Yampa <br />Rivers. <br />Specimens of the humpback chub complex (Holden and Stalnaker, 1970) have <br />recently been collected in Echo Park on the Green River (McAda and Seethaler, <br />1975) and in Desolation Canyon (Holden and Stalnaker, 1975a). Specimens <br />most nearly representing the G. c ha type species, have been collected from <br />the Colorado River in Ruby Canyon (McAda et al., 1977). <br />A fish collected in the lower river (Figure 22) was identified as a <br />roundtail chub (Gila robusta) in the field. Its length was 345 mm and it had <br />bright red spawning colors on the ventral part of the body. Later examination <br />of several photographs (Figure 22) taken of the fish indicated it was not a <br />roundtail chub but was either a bonytail chub (Gila elegans) or a Gila ele ans <br />x Gila c ha hybrid (P. Holden, BioWest, Inc., personal communication). <br />Bonytail Chub (Gila ele ans) <br />The bonytail chub is the most streamlined of any fish found in the <br />Colorado River basin. The dorsal surface on the skull is concave and arches