8117

• UCREFRP Catalog Number: 8117
• Author: Modde, T. and G. Smith.
• Title: Flow Recommendations for Endangered Fishes in the Yampa River.
• USFW Year: 1995.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

J'" chub

Adult humpback chubs (230 mm) have been collected in canyon-bound areas
in the lower35 miles of the Yampa River (Figure 3, from Tyus and Karp
1989) (Tyus et al. 1982a, Karp and Tyus 1989, Fish and Wildlife Service and
Colorado State University unpublished data) and in the lower Little Snake
River and Upper Yampa Canyon by Fish and Wildlife Service and Colorado
State University (unpublished data). Adult humpback chubs were most often
collected in eddy habitat (average depth, 2 m), particularly in shoreline
eddies created by large boulders and rapids (Karp and Tyus 1989). Radio
telemetry monitoring of an adult humpback chub near Mathers Hole (RM 19)
in 1993 indicated only localized movement during the summer months
(Colorado State University, unpublished data). Two adult humpback chub
implanted with radio transmitters in the lower nine miles of the Little Snake
River in June 1995, moved downstream into Yampa Canyon in late July as
flows in the Little Snake River declined (Fish and Wildlife Service~
unpublished data).

Juvenile (less than 230 mm) humpback chub have been collected between
RM 0.1 and 40 in Yampa Canyon by the Fish and Wildlife Service (Karp and
Tyus 1989). Identification of juvenile Gila as the humpback form was based
on the same complex of morphologic characters use to differentiate the adult
life history stage (Karp and Tyus 1989). Most young humpback chubs were
captured in shoreline eddies and runs. Problems with specific identification
of small chubs has hindered the evaluation of habitat needs of small
humpback chub.

Razorback sucker

Adult razorback sucker have been collected between RM 13 and RM 0.1
(Fish and Wildlife Service, unpublished data) of theYampa River. In 1979
one adult razorback sucker was collected in Lily Park (Ed Wick and John
Hawkins, Colorado State University, Personal Communication). Most fish
have been collected during the spring at a documented razorback sucker
spawning site located in the Yampa River just upstream from its confluence
with the Green River. Telemetry data indicate that some fish spawning in the
Yampa River may reside the remainder of the year in the Green River
(Modde et aI., in preparation). Tyus (1987) o~served nonbreeding adult
razorback sucker occupying shoreline runs and sites near midchannel sand
bars (depths < 2 m) on the Green River, while Modde et al. (in preparation)
observed razorback sucker using deeper habitats associated with deep runs
and eddies as weli as shallow habitats. Adult razorback suckers were
observed to overwinter in Echo Park (McAda and Wydoski 1980, Valdez and
Masslich 1989).

Only one juvenile razorback sucker has been collected in the Yampa River.
The single fish, a 389 mm juvenile, was collected at RM 39 in June 1994
(Fish and Wildlife Service, unpublished data). Razorback sucker have been