7354

• UCREFRP Catalog Number: 7354
• Author: Wydoski, R. S.
• Title: Biological Review of Endangered or Imperiled Fish in the Upper Colorado River Basin.
• USFW Year: 1985.
• USFW - Doc Type: Washington, D. C.
• Copyright Material: NO

Table 2. Biological Summary of Rare Colorado River Fish (continued)
item Humpback Chub
6` 11 a SyL
Status/Distribution
Age and Growth I
(TL in mm) II
III
IV
Y
Maximum Size
Maximum Age
Reproduction
Endangered; Absent from such of its historic range;
Fewer fish in present range; See Figure 2 for summary
of distribution and identification of sensitive areas.
Little Colorado River
n-192 -
119
269
278
313
363
,57 mm
6 years
Size/Age at Maturity 200-300 mm TL; unknown
Fecundity hatchery; na7; average 2.523 (2.392/lb.)
hatchery; n:9; average 3.333
hatchery; n?3; average 6'.000
Spawning Period late JuBe - early July
Temperature at Spawning 13 - 20 C
Streamflow at Spawning Descending Hydrograph
620-310 m /sec.
Food Habits Young - diatoms and small invertebrates.
Adults - invertebrates; midges and blackfly larvae were
predominant in one study although larger organisms
(e.g. freshwater shrimp) were available.
Anglers catch them using worms and grasshoppers as bait. One
investigator reported that they fed on floating terrestrial
insects and could be caught readily on artificial flies at that
time.
Habi tat
Little Colorado River
Young - Less than 3 ¦. deep; water velocity less than 30 ca/sec.;
silt substrate.
Juveniles - Water from 3-9 m. deep; water velocity less than
30 ca/sec.; silt. sand, or gravel substrates.
Adults - Deep water 3-9 ¦. deep; water velocity less than
30 ca/sec.; silt, sand, boulder. and bedrock.
Colorado River Mainstream
Inhabit P@ s in deepwater canyon areas; average water depth in
Black Rocks and Westwater Canyons. near the Colorado-Utah
border, was 15.2 ¦. deep with vertical rock walls and bedrock
substrate (maximum of 28 m.)
Movement Radio-tracked fish did not move more than 1 river mile from
where they were tagged.
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