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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percentage of total fishing that is done in streams is somewhat higher

Table 3. Types of Waters Fished Most Often by Freshwater Anglers Twelve Years
Old and Older in the United States in 1970

than the average for the United States but the percentage done in res-

ervoirs is far higher in the Mountain states (46,6 percent) than else-

a
TYpe of freshwater fishin~ (percent )
Thousands of Natural lakes Rivers and Total
Region fishermen Reservoirs Ponds and ponds streams
United 100.0
States 29.363 28.1 13.3 27.2 31.4
Mountai.~ 1.752 46,6 3.1 15.9 34.4 100.0
states

where in the United States (average 28,1 percent) (table 3).

As water resources development increases in the Upper Colorado

River. more streams will be impounded and more fishing will become

available in man-made reservoirs or in the tailwaters. In a small

percentage (4,7 percent) of the fluctuating reservoirs in the Moun-

tain region of western United States. wild trout make up as much as

~: U.S. Department of the Interior. Bureau of Sport Fisheries and
Wildwife, 1970 National Survey of Fishin~ and Huntin~. Resource Publication 95
(Washington. D,C.. 1972).

20 percent of the total catch (table 4). This percentage is somewhat

rado River Basin (Colorado, Utah. and Wyoming). Nevertheless. the

aAs percentages of total fishermen,

bThe Mountain states include Arizona, Colorado. Idaho. Montana. Nevada.
New Mexico. Utah, and Wyoming,

higher (6.1 percent) for reservoirs in some states of the Upper Colo-

fishery in most of these reservoirs must be sustained by stocking be-

p
.

cause self-sustaining trout populations have not become established,

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...
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The main factors that appeared to ltmit trout production in 105 Idaho

reservoirs were a paucity of/spawning or nursery areas (69.5 percent

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of the reservoirs). drawdown (62,9 percent). competition (51,9 percent).

temperature (31.4 percent). food supply (19,0 percent). and dissolved

oxygen (15.2 percent) (Gebhards. 1975). Gebhards reported that a poll

of the eleven western states indicated that the limiting factors were
1
s~ilar in all; they were identified as lack of spawning or nursery

areas. excessive fishing pressure. drawdown, competition, and unfavorable

water temperature.

1
The eleven western states include: Arizona. California, Colorado,

Idaho, Montana, Nevada, New Mexico, Oregon. Utah. Washington, and Wyoming.