6007

• UCREFRP Catalog Number: 6007
• Author: Carter, J. G., R. E. Valdez, R. J. Ryel and V. L. Lamarra
• Title: Fisheries Habitat Dynamics in the Upper Colorado River
• USFW Year: 1985
• USFW - Doc Type: Journal of Freshwater Ecology
• Copyright Material: YES

These dynamics in total habitat are clearly shown to be a function of
discharge in Figure 11. From these analyses, it appears that potential fish
habitat was at a maximum during peak flows in late June. However, much of
the habi tat at that time consi sted of deep mi dchannel runs and rapi ds that
seem to force fish into a few marginally suited shoreline-associated
habitats such as flooded woodlands and large backwaters. These habitats are
considered marginal because of their instability during high flows and the
intense competition and predation brought about by the concentration of
fishes. At lower flows, the habitat becomes more diverse and moderate (less
turbulence and velocity), and enables fishes of different species and sizes
to occupy a greater variety of suitable microhabitats. That dramatic change
from a swollen, turbulent, swift-flowing river to a more confined, moderate-
flowing one occurs near Parachute at about 10,000 cfs.

Management Implications

The resul ts of thi s study are a step toward a better understanding of
habitat dynamics in the Colorado River. It was shown that the surface area
of several of the habitat types are predictable functions of flow within
this reach of river. Similar patterns are likely in similar reaches of the
Colorado River; however, the specific relationships between flow and habitat
area may differ somewhat due to small, localized differences in channel
morphology and land use practices. In reaches of the river where the
channel morphol09Y is qui te di fferent, a somewhat different set of
relationships may be expected.

1000

BODO

7000

1000

.;-
1/1 !'QOO
o
o
52
x
........ .4.000
"
~
<(

1000

2000

1000

JULY

AUGUST

1983

Figure 10. Habitat area as a
function of time between
6 June and 2 September 1983
for the Colorado River study
area near Parachute, Colorado.

1000

1000

7000

1000

.;-
.. 5000
o
o
52
x
........ ..ODD
"
~
<(

3000

2000

tOaD

6000

12000 18000 24000 30000
Discharge (cIs)

Figure 11. Habitat area as a
function of discharge between
3 March and 2 September 1983
for the Colorado River study
area near Parachute, Colorado.

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