8003

• UCREFRP Catalog Number: 8003
• Author: Haynes, C. M. and R. T. Muth.
• Title: Identification of Habitat Requirements and Limiting Factors for Colorado Squawfish and Humpback Chubs ‎(January 1, 1981 to June 30, 1982)‎.
• USFW Year: 1982.
• USFW - Doc Type: SE-3-4,
• Copyright Material: NO

~~ ~ ~~ ~~- ~ ~do~j
,
JOB PROGRESS REPORT
State of COLORADO
Project No. 5E-3-4 Endangered Wildlife Investigations
Work Plan No. 1 Job No. 1
Job Title Identification of Habitat Requirements and Limiting Factors
-for Colorado squawfish and Humpback Chubs
Period Covered: ~:~#
Personnel: C.,~, R. Muth, G. Skiba, L. Wycoff
~.
ABSTRACT
Field collections were made in two study areas in the Upper Colorado River
drainage during January 1, 1981 through June 30, 1982. Field and
laboratory methods are presented. Identif ications, counts and measurements
of 1981 samples are completed and Yampa River data has been stored on the
FWS MANAGE computer program (Colorado State University). Preliminary lab
processing of 1982 samples will be initiated in fall, 1982. In 1981,
Yampa River samples were dominated by red shiners (7563 individuals)
and, overall, introduced species were more numerous both in number of
species (11 of 18 taxa) and individuals (9660 versus 9398 natives).
In the Colorado River, 17 species were collected of which 11 were introduced.
Red shiners and fathead minnows were the predominant species with 24,353
and 16,019 individuals, respectively. In 1981, 23 Colorado squawfish
were collected in the Yampa study area during July and August. All were
collected in the lowermost 20 km of the Yampa Canyon, Dinosaur National
Monument. Only one squawfish YOY was collected in the mainstem Colorado
River. This individual was collected at a site in Mesa County west of
Grand Junction in July. Analysis of known-age hatchery-reared humpback
chubs is presented and analysis of various genetic crosses of humpbacks,
bonytails, and roundtails in addition to known-age bonytails and roundtails
will begin in fall, 1982. Those analyses will be used to evaluate
unknown field-collected chubs for the possible presence of humpbacks in
the study areas.

This Job Report represents a preliminary analysis and is subject to change.
For this reason, information presented herein MAY NOT BE PUBLISHED OR
QUOTED without permission of the Director.
~`