|
<br />.
<br />
<br />~
<br />
<br />..
<br />
<br />< .
<br />
<br />.
<br />
<br />UatlI ce-K/
<br />(C{70
<br />
<br />"
<br />
<br />;-
<br />
<br />KriLl t\fJ' '*' 'f'p,~liti.
<br />
<br />r
<br />
<br />c .
<br />I
<br />.. .
<br /> t
<br /> I
<br /> I
<br /> I
<br /> I
<br /> I
<br /> I
<br /> t
<br /> I
<br /> i
<br /> I
<br />.. t
<br /> t
<br /> t
<br />
<br />h"_'
<br />
<br />.~___,~ M'.,",'
<br />-
<br />
<br />07?:1]
<br />
<br />THE SOUTHWESTERN NATURALIST 14(3): 297-315
<br />
<br />JAN. 15, 1970
<br />
<br />DISTRIBUTION OF GREEN RIVER FISHES IN
<br />UTAH AND COLORADO FOLLOWING CLOSURE
<br />OF FLAMING GORGE DAMl
<br />
<br />C. DAVID VANICEK
<br />
<br />Department of Biological Sciences, Sacramento State College, Sacramento, California
<br />
<br />ROBERT H. KRAMER2 and the late DONALD R. F!lANKLIN3
<br />Utah Cooperative Fishery Unit, Utah State University, Logan, Utah
<br />
<br />ABSTRACT, Flaming Gorge Dam on the Green River, Utah was closed in
<br />November, 1962, Studies of fish populations from the dam downstream to Ouray,
<br />Utah, were conducted from July, 1963, to October, 1966, The objectives of these
<br />studies were: 1) to study changes in river environment associated with closure of
<br />the dam; 2) to determine species composition, distribution, and abundance of fishes
<br />in the study section; and 3) to compare 1963-1966 distribution of fishes with that
<br />reported in pre-impoundment collections, A total of 24,040 fish consisting of 9 in-
<br />digenous and 12 exotic species was taken in 667 collections by electrofishing gear,
<br />gill nets, seines, and fry gear. Flaming Gorge Dam has caused a major change in
<br />the ecology of the downstream Green River by alteration of seasonal flows and water-
<br />temperature patterns as far as the mouth of the Yampa River, 65 miles below the
<br />dam, As a result, native fish populations, particularly in the first 26 miles below
<br />the dam. have been largely replaced by introduced rainbow trout (Salmo gairdneri).
<br />Below the Yampa River mouth, fish populations were similar to those reported dur-
<br />ing the pre-impoundment years, During years of high summer discharge from the
<br />dam with resultant lower water temperatures (1964 and 1966), no reproduction of
<br />any native fishes was found in the Green River above the mouth of the Yampa River.
<br />
<br />Flaming Gorge Dam, a unit of the Colorado River Storage Project,
<br />was completed in November 1962, by the Bureau of Reclamation. This
<br />4055-foot high, arch-type concrete dam is located on the Green River in
<br />lower Red Canyon in Ashley National Forest in northeastern. Utah. Its
<br />primary purposes are generation of hydro-electric power and regula-
<br />tion of river flow. High dams such as this discharge water from lower
<br />depths of the reservoir into the tailwaters and often modify the doV\-n-
<br />stream river environment in the following ways: 1) average annual
<br />water temperature is lowered, although water temperature may be
<br />
<br />1 Portion of a doctoral dissel1ation written at Utah State University.
<br />2 Present Unit Leader, Bureau Sport Fisheries and Wildlife,
<br />3 Fonner Unit Leader, Bureau Sport Fisheries and Wildlife.
<br />
<br />297
<br />
<br />^,-s;- ____,._..........,.."""_.-___.____....-~____._---..___'""~"_'_
<br />
<br />~
<br />
<br />"
<br />
<br />,
<br />
|