7155

• UCREFRP Catalog Number: 7155
• Author: Holden, P. B., W. White and G. Somerville
• Title: Threatened Fishes of Utah
• USFW Year: 1974
• USFW - Doc Type: 51, Part 2
• Copyright Material: YES

. ,

,.;.

.

,~.

.

"

, -
.>

..

S3

UTAH ACADEMY PROCEEDINGS, VOL. S 1, PART 2, 1974

-

Figure 2. Bony tail chub (top) and humpback chub adults.

Holden and Stalnaker (1970) suggest the humpback might be best con-
sidered a subspecies of the bony tail. The term humpback chub will be used
here to refer to those humped Gila not bony tails. Characters separating
these two groups are: caudal peduncle deeper in humpback than bony tail
(0.049-0.057 of S.L. to 0.035-0.049 of S.L. respectively); overhanging
fleshy snout in humpbacks, not in bony tails ; humpbacks have a more
abrupt nuchal hump with a crease separating head and trunk; dorsal fin
rays usually 9 or 10 in humpbacks and 10 in bony tails. Holden (1973)
reports collecting juvenile chubs that appear to be humpbacks. They were
distinguished from other chubs by a nuchal hump.
Documentation: Endemic to the CuoradoRiver basin, the humpback
chub appears restricted to the swift water canyons. It was first reported in
the 1940s from Grand Canyon (Millei', 1946). Since that time it has rarely
been found and never in great numbers. Miller (1955) reported remains of
this fish from Indian ruins in the lower Colorado basin, indicating some
degree of abundance in prehistoric times. The humpback chub has not
been collected in recent times below the Grand Canyon. It was considered
rare in the upper basin by Holden (1973). In Utah, humpback chubs are
found in the Green River in Desolation Canyon and in Lake Powell, where
they are declining. They are also found in the Green and Yampa Rivers of
Colorado in Dinosaur National Mon~nt and in the Grand Canyon area
of Arizona. Reproduction appears likely for this form in Desolation
Canyon (Holden, 1973).

~__~",,,,,~,--,,,,~~,,,,,"..~_~.-.-.._t'___~_ _,

.>

~~

.

.

.

+

.I'

,

.,