3125

• UCREFRP Catalog Number: 3125
• Author: Wick, E. J., et al.
• Title: Colorado Squawfish and Humpback Chub Population and Habitat Monitoring.
• USFW Year: 1984.
• Copyright Material: NO

5
with water years to establish relationships.
RESULTS AND DISCUSSION
Seethal er (1978) calculated total lengths for Colorado squawfish of the
Colorado, Green and Yampa Rivers. These total lengths, when compared to the
total lengths computed for Yampa River specimens of Colorado squawfish (Tables
1 and 2), made me hypothesize that I overlooked one annulus. Therefore, all
calculations for Yampa River specimens of Colorado squawfish were moved back
one year (computed Age IX+ is actually an Age X+ Colorado squawfish).
Colorado squawfish scales exhibit a very high proportion of regeneration.
Approximately 50 Percent of the scales removed from Colorado squawfish from the
Yampa River were -ado squawfish scales are also very dif_°_cult
to analyze. The anterior field of the scales was often unclear and a diagonal
analysis had to be used. Annuli then could be followed to the anterior field
for measurement. Because of the problems encountered with the analysis of
Colorado squawfish scales and the high percentage of regeneration, many scales
should be removed from each specimen and only the perfect scales should be
analyzed. Analysis of Colorado squawfish scales is possible if the above
criteria are met.
Colorado squawfish captured in the Yampa River in 1982 were VI+ to XII+
years old (Table 3). Causes for low numbers of VI+ and VII+ Age Colorado
squawfish are discussed in the section dealing with flow and temperature data.
Seethaler (1978) collected and aged Colorado squawfish scales collected from
the Colorado River. Similarities were noted between year classes of Pampa
and Colorado squawfish (Figure 1). The age class VIII+was dominant over all
other year classes in both rivers. Since the Yampa River fish were captured