7740

• UCREFRP Catalog Number: 7740
• Author: McAda, C. W. and L. R. Kaeding.
• Title: Physical Changes in the Gunnison and Colorado Rivers Resulting from Construction of the Aspinall Unit and Related Projects, with Hypotheses to Assess the Effects on the Endangered Fishes
• USFW Year: 1991.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

Nc
G
2
~_
L.L
.~
LL,
U
z
Q
w
w
O
u,
C~
.20
.15
.10
.05
0
85
86 TT
87 ~ 1
88 ~ 83
~ T 84
2 I I
i i i i
10 20 30 40 50 60 70 80
MAXIMUM-ANNUAL DISCHARGE (CFS X 1000)
Figure 8. Plot of geometric-mean catch per effort (C/E) versus maximum-annual
discharge (stateline gage) for post-larval Colorado squawfish collected
in the Colorado River between river miles 0 and 110 during October,
1982-1988. Lines indicate ± 1 standard error; numbers indicate year of
collection. Excerpted from McAda and Kaeding (1989).
the observed differences: none-the-less, spring runoff is obviously important
to successful reproduction by Colorado squawfish.
Numerous investigators have found relations between maximum-annual
discharge and the relative abundance of other fish species (McAda and Kaeding
1989; Osmundson and Kaeding 1989, 1990; Valdez 1990). Considerable variation
exists, but in general, relative abundance of young-of-the-year of native
species is positively correlated with maximum-annual discharge and relative
abundance of introduced species is negatively correlated with the same value.
Osmundson and Kaeding (1989) observed that fathead minnow Pimephales promelas,
red shiner Notropis lutrensis, and sand shiner N. stramineus developed large
26