6013 - Laserfiche WebLink

Home Browse Search

H~anpback chubr •re relatively eo~on in Desolation-Gray canyon• in the Little Colorado Aiver (personal communication, •C. (Holden 1977). Hinckley, Museum of Northern Arizona),. and the Black Rocks area of Colo- rado (Kidd 1977). The Desolation-Gray canyons area probably contains the largest population, as the other two areas have less suitable habitat. The Little Colorado Aiver is serving as a refugium for the Crand Canyon population from the cold, f luctuatiag conditions of the Colorado River in that area. Humpback chubs are relatively rare is the Green and Yampa rivers of Dinosaur National Monument where they usually have been takes from one or two rather restricted reaches (Holden and Stalnaker 1975; Seethaler et al. 1976). Life Hist~ No avecific research has been conducted an humpback chub life mentioned previously. Therefore, history except the microhabitat study life-history information must be extrapolated from data on closely ze- lated species (boaytail and roundtail chubs) and the occasional observa- tions of field researchers. Spawning of roundtail and-bonytail chubs appears to occur at river te~peratu=es of approximately 18°C (yanicek and Kramer 1969; Holden 1973). Due to the close systematic relationship between these species and the humpback chub, it is reasonable to assume that similar temperatures are required-by the~hunpback-chub. Paul Holden (personal communication, Logan, Dtah) collected a ripe male humpback chub in the lower .Yamaha River The specimen had at the same time that roundtail males were ripe there. alight breeding tubercles in the dorsum and splashes of orange-coloration near the paired fias;,similar to that noted in roundtails and bonytaila. Size of humpback young in Desolation and Gray canyons is September or June whey water temperature suggests that spawning occurs in May first reaches 18°C. Suttkus and Clemaer (1977) stated that spaWaing of humpback-chubs "probably-vccuYS~during June and July is the Grand Canyon area." Growth of young humpbacks, as shown by length/frequency analysis indicates that is 5e tember Desolation Canyon young-of- (flolden 1977), p ' the year 'arc'30-70 a,m and juveniles (age I and IIZ) are 70-150 mn. 7