7378

• UCREFRP Catalog Number: 7378
• Author: Wydoski, R. S.
• Title: Potential Impacts of Alterations in Streamflow and Water Quality on Fish and Macroinvertebrates in the Upper Colorado River Basin.
• USFW Year: 1980.
• USFW - Doc Type: 77-147
• Copyright Material: YES

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Table 4. Fluctuating Reservoirs in the Mountain Region of the Western
United States with Wild Trout Fisheries

Most reservoirs in the Mountain states are large; an average of 90.4

percent are larger than 16 hectares (39.5 acres) (table 5). This percent-

age is somewhat higher (91.4 percent) for some states of the Upper Colo-

Total number of Reservoirs in which wild trout
State reservoirs composed 20% or more
of the total catch
Wyoming 330 2
Colorado 250 30
ldaho 105 14
Utah 99 0
Nevada 61 3
Montana 31 3
Arizona 28 0
New Mexico 12 4
Total 916 56

rado River Basin (Colorado, Utah, and Wyoming). As indicated in the pre-

ceding paragraph, the general management of these reservoirs consists of

stocking--usually with fingerling rainbow trout, The stocked fingerlings

feed primarily on zooplankton, benthic organisms. and sometimes terres-

trial insects that fall into the water (Varley. Regenthal. and Wiley. 1971).

Usually, these fish do not become piscivorous. and other fish species in-

variably proliferate in new impoundments and are considered to be serious

competitors with trout (Gebhards. 1975). The management of undesirable.

nongame species such as carp and Utah chub (Q!!! atraria). as well as var-

ious species of suckers and shiners. in reservoirs is one of the principal

problems confronting state fishery management agencies in this region.

Techniques are needed for the manipulation of these populations of unde-

Source: S. Gebhards. "Wild Trout: Not by a Damsite." in W, King,
ed" Wild Trout Mana~ement (Denver, Colo., Trout Unlimited. Inc.. 1975).

sirable species, since eradication is hardly possible in the large reser-

voirs such as those found in the Upper Colorado River Basin.

Management problems are compounded when large fish are caught in

these reservoirs, such as the world-record brown trout (Salmo ~rutta)

from Flaming Gorge Reservoir. Should the agencies responsible for the

management of these reservoirs direct their efforts toward the manage-

ment of smaller rainbow trout that are sought by most anglers or toward

the management of fewer. but larger. brown trout or lake trout (Salve-

.il!!!!! namavcush) that will be caught by fewer anglers? Should agencies

attempt to control the nongame species such as Utah chubs that compete

with the rainbow trout, or should they leave them as forage for large

brown trout and lake trout?

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