7145

• UCREFRP Catalog Number: 7145
• Author: Inslee, T. D.
• Title: Spawning of Razorback Suckers
• USFW Year: 1981.
• Copyright Material: NO

50,000
HISTORIC
® RECENT
40,000
U
LU
00 30,000
F-
LL.
U
20,000
U
10,000

52%
47%
SAN JUAN COLO GREEN
BLUFF STLN JENSEN
Figure 11. Change in mean peak flow (highest flow day of the year) for
three upper Colorado River basin rivers. Historic and recent periods for
each river are given in Figure 10. Percentages describe proportion of
historic mean peak flow that recent mean peak flow provides.
rivers (Fig. 11). Although other factors are no doubt associated with the
decline of these species, we hypothesize that differences in the present
status of endangered fish populations among rivers is in part related to
the degree of alteration of the natural hydrograph.
Razorback Sucker
The razorback sucker, the other rare fish that inhabits the Grand Valley,
has repeatedly exhibited spawning behavior within the 15-mile reach
(George Kidd personal communication, Valdez et al. 1982, Osmundson and
Kaeding 1989). The status of this species is very precarious. Though
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