8291

• UCREFRP Catalog Number: 8291
• Author: Chart, T. E. and L. D. Lentsch.
• Title: Flow Effects on Humpback Chub ‎(Gila Cypha)‎ Populations in Westwater Canyon.
• USFW Year: 1997.
• USFW - Doc Type: Aspinal-46,
• Copyright Material: NO

WESIINATER CANYON: 1992-1996
YOY CHUB GROWTH VS DEGREE DAYS
0.9
0.8
~ 0.7
ca
~ 0.6
E
E
= 0.5
0.4
~ 0.3
0.2
0.1
__...--- _.g..._ .~....._.._._.._.._..__..__.----..._._...._.
o $ o^z
^
- z z .._.._.._._
^
z
0 ~ 100 200 300 .400 500
MONTHLY DEGREE DAYS (> 20C)
^ above canyon july z above canyon august
~ -a- canyon july S canyon august
Figure 5. •• Correlation of daily growth (mm~day) for YOY chubs collected in July and August in
the above Westwater Canyon and Ca~-on sub-reaches to accumulated monthly degree days
(>20°C) . Thermal data collected by the USGS ax the Near Cisco gage (No. 09180500): 1992-
1996.
Chub YOY Cohort Relative-Abundance
Sampling for YOY occurred throughout the summer, but mam- of the following analyses
considered only 7uly and August collection data. During these months YOY were most abundant
and still preferred low velocity areas opposed to Bowing water habitats. This shift in habitat
Preference typically occurred in September or when the YOY grew to 40 - SOmm TL. [During
the September, 1996 frsh comm:n:ity trip more YOYwere collected electrofishing the shoreline
than with seines in low velocity areas.) Young of the year chubs were collected in all three
sample strata with 1668 collected above the canyon (RM 127.5 - 124.6), 1477 in Westwater
DRAFT '
• ~ - - •' 12