8062

• UCREFRP Catalog Number: 8062
• Author: Langlois, D.
• Title: Status of the Razorback Sucker and Bonytail Chub in Western Colorado.
• USFW Year: 1977.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

classes were found in the area until 1964, when few young-of-the year and
yearling fish were observed downstream from the dam. They concluded that the
environmental requirements of the bonytail chub were no longer being met in
that stretch of the Green River. Holden and Stalnaker (1975) sampled the
lower Yampa River and the Green River below the mouth of the Yampa River in
Dinosaur National Monument from 1967 to 1973. Only 36 specimens were taken
and they concluded that the species was rapidly losing ground in an area where
it was recently abundant.
David Starr Jordan (1891) seined several bonytail chubs from the
Gunnison River near Delta, Colorado. -Recent studies by Kidd (1974; 1977)
during the early 1970's found no bonytail chubs in either.the Colorado River
or Gunnison River in Colorado. Kidd also collected 16 miles of the lower
Yampa River in 1972 and 1974 and found no bonytail chubs. Prewitt and Carlson
(1976) failed to collect any bonytail chubs from the lower Yampa River. Thus,
records of bonytail chub distribution exist for the Gunnison River upstream
to Delta, Colorado, the Colorado portion of the Green River, and the mouth
of the Yampa River in Dinosaur National Monument. Green and Yampa River popu-
lations have declined greatly since the closure of Flaming Gorge Dam. Little
can be said about changes in abundance in the Colorado and Gunnison Rivers,
except that no specimens have been found in recent years.
Both species have been reduced in numbers and range in Colorado
since the turn of the century. Some authors consider both fishes to be quite
rare.
REASONS FOR DECLINE
Some 30 years ago, R. R. Miller (1946) pointed out the urgent need
for ichthyological surveys of the major rivers in western North America because
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