7362

• UCREFRP Catalog Number: 7362
• Author: Karp, C. A. and H. M. Tyus.
• Title: Habitat Use, Spawning, and Species Associations of Humpback Chub,
• USFW Year: 1989.
• Copyright Material: NO

temperatures at which we captured ripe fish were similar to the 14-240C
range noted by Kaeding et al. (in press), but slightly higher than the
11.5-160C temperatures noted by Valdez and Clemmer (1982), both in the
upper Colorado River. Capture of few ripe female chubs (5 humpback and 5
roundtail chubs, 4% of all breeding captures) may suggest that females are
ripe for a limited time and thus, experience a short spawning period.
All humpback chub (including ripe adults) were captured in shoreline
eddies, indicating that the fish spawned in these quiet-water habitats or
in nearby areas. Although limited, recapture data (N=11) indicated that
adult fish exhibited a fidelity to specific eddy habitats during the
spawning period. Ten of the 11 fish were recaptured in the same eddy as
the initial capture (50% in two different spawning seasons) and 73% were
captured in breeding condition at least once. Although we did not
investigate movements of humpback chubs, seasonal loss of their spring
habitats (habitats created by high spring runoff) due to declining flows
indicated that the fish leave such areas after the spawning period. Our
observations of chubs in pools near Big Joe Rapid (km 38.4) in September
1989 suggested that during low-flow periods, the fish moved into impounded
and relatively deep habitats and remained within the 48 km spawning reach
in Yampa Canyon.
Humpback and roundtail chubs were sympatric in DNM, but humpback
chubs appeared to inhabit only deeper water habitats whereas roundtail
chubs were ubiquitous and also inhabited riffles and shoreline runs. The
temporal and spatial overlap in spawning we noted for humpback and
roundtail chubs has also been observed in the upper Colorado River
(Kaeding et al., in press). The low number of intermediate (or possible
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