9384

• UCREFRP Catalog Number: 9384
• Author: Valdez, R. A. and R. J. Ryel.
• Title: Summary of Recovery Goals for the Four Endangered Fishes of the Colorado River Basin.
• USFW Year: 2000.
• USFW - Doc Type: Logan.
• Copyright Material: NO

Humpback Chub - 4

T blIP r .

I .

fi d I h

b k h b'

I f

a e re lmmary popu atIon estImates or a ut ump ac c u m SIX popu a IOns.
Population Population 95% Reliability of Estimate Kilometers Citation
Estimate Confidence Occupied
Intervals
B lack Rocks 1,528 888-2,750 Reliable . 3.7 Ryel (1998)
Westwater Canyon 5,186b not available Not currently reliable; 12.9 Chart and
data available to improve Lentsch (1999)
precision
Grand Canyon --Little 4,508 4,330-4,811 Last estimate of 1993 ]4.9 Doug]as and
Colorado River outdated Marsh (1996)
Grand Canyon--Colorado 225c not available Last estimate of ] 993 294.9 Valdez and Ryel
River outdated 1997)
Yampa Canyon 600d not available Not currently reliable 73.6 Karp and Tyus
] 990)
Desolation-Gray Canyons 1,500" not available Not currently reliable 62.8 Chart and
Lentsch (1998)
Cataract Canyon 500f not available Not currently reliable 19.3 Valdez (1990)
TOTALS: 14,047 236.6

Table 2. Target numbers of humpback chub needed in populations or population complexes for
genetic and demographic viability.

Age I Survival A Number Proportion of Population
I (lower and upper range) (lower and upper range)
3 I 0.76 I 630 0.24
I
(500 - 860) (0.20 - 0.30)
4+ 0.76 i 2,000 0.76

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