9383

• UCREFRP Catalog Number: 9383
• Author: SWCA, I.
• Title: Recovery Goals for the four Colorado River Endangered Fish Species.
• USFW Year: 2000.
• USFW - Doc Type: Logan.
• Copyright Material: NO

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

Glen Canyon Dam to increase the range of the current population upstream and reduce the
n with nonnative salmonids. Another action is to potentially locate and establish a
opulation within the Grand Canyon reach of the lower Colorado River. However,
recovery criteria for humpback chub in the Lower Colorado River Basin are yet to be determined.
San Juan River Basin

There has been no historical evidence, nor are there currently, any humpback chub in the
San Juan River Basin; hence no recovery actions, plans or criteria exist or are expected for the
species in this basI

Table 3. Preliminary population estimates for adult humpback chub in five populations. Best
first estimate will be used when current estimate is not considered reliable.

Population Population 95% I Reliability of Estimate Kilometers Citation
Estimate Confidence Occupied
Intervals
Black Rocks 1,528 888-2,750 Reliable 3.7 McAda (1999)
Westwater Canyon 5,186b not available Not currently reliable; 12.9 Chart and
data available to improve Lentsch (1999)
precision
Yampa Canyon 600d not available Not currently reliable 73.6 Karp and Tyus
1'1990)
Desolation-Gray Canyons 1,500" not available Not currently reliable 62.8 Chart and
Lentsch (I 998)
Cataract Canyon 500f not available Not currently reliable 19.3 Valdez (1990)
TOTALS: 14,047 236.6

Table 4. Target numbers of humpback chub needed in popul ~ or population complexes for
genetic and demographic viability.
Age Survival A Number Proportion of Population
(lower and upper range) (lower and upper range)
3 0.76 630 0.24
(500 - 860) (0.20 - 0.30)
4+ 0.76 2,100 0.76

29