4206

• UCREFRP Catalog Number: 4206
• Author: Armantrout, N. B.
• Title: Endangered Fish of the Colorado
• USFW Year: 1978
• USFW - Doc Type: Changes in the Environment of the Colorado River Pose a Threat to Native Fishes
• Copyright Material: YES

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of the Colorado siphoned on and
carried, via fipelines, for
hundreds 0 miles to make possi-
ble the urban and agricultural
development of the southwest.
The demands for water have
changed the nature of the River__,
rnverarr flow has dechne~'
~fthe remaining watef-high~
'JaltU_r1.d..se<fiment~. Tl:Je spring
~f100ds have lieen reduced or
eliminated, and ~fle old annual )/
BYcles of low water and high wa?
~e now a thing of the pjs.l-/
Dams have now lurned long
stretches of the once raging river
into quiet lakes. Below the dams,
waler flowing through the power
turbines comes out so cold and
clear that it is suitable for trout.
But this is a far cry from the warm,
silty water in which the native
fishes thrived.
As the river changed, so did
the fish. New species were in-
troduced and thrived in the cool-
er, clearer water. Some native
species, especially some of the
suckers and smaller minnows,
survived too, and even pros-
pered, but there were four spe-
cies-that could not adapt to the
new conditions. Two of these,
the Colorado squawfish and the
humpback chub, were among the
first fish to be listed as endan-
gered by the U.S. Fish and Wild-
life Service. The other two have
since been proposed for listing;
the bonytail chub as an endan-
gered species and the humpback
sucker as threatened. Even before
the Federal Government took ac-
tion, several states along the Col-
orado River had acted to protect
these once numerous fishes.
Two of the four species were
so numerous at one time that
they supported an active fishery.
The Colorado squawfish, the larg-
est minnow in the United States,
reached a length of six feet and
weighed close to one hundred
pounds. It was taken as a food
fish and eaten fresh or smoked.
Because it made migrations up-
stream, the early settlers called it
the "Colorado River Salmon." It
was considered an excellent food
fish and supported a commercial
fishery, for many years.
While less prized by early set-
tlers, the humpback sucker had a

317.48; 0 . 78 . I

Fisheries biologIsts
set a seine in an in-
ventory of'endan-
gered fish in Green
River's DesolatIon
Canyon. The Green is
a tributary of the
Colorado River.

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tt..l;;!;", - . ..' .' - . ;4~:;(_~~~~~ 7" ...,.-
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This stretch of
the Green River
Is thought to
have had the
least change of
any fisheries
habitat in the
Colorado River
system.

.. .

much longer history in the kitch-
en. From earliest times the Indi-
ans living in the canyon took the
humpback sucker and made it an
important item in their diet.
The bonytail and the humpback
chub were not caught as often as
the other two. In fact, the hump-
back chub was not described in
scientific literature until well into
the 20th century, and it was never
abundant. The bonytail chub,
once abundant, is now seldom
taken anywhere In the river sys-
tem. Its numbers have declined
more than any of the other three
species.

The four species have not only
declined in numbers, but their
distribution throughout their
former range is now restricted.
Recent studies show that these
fish are now missing from most
of their former range. Nowhere
are ti!~y abundant. )Jhe=t~st(
(populations are found in thos~'
t., areas of the river syste~1"!! where]
~-m-s~~ the least chang~.
--nns-rs-mcrinfy ahove-the-CIei1
Canyon Dam which is on the
Utah-Arizona border.
The decline in population is
due both to changes in the river
and because of competition from

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