Flaming Gorge Reservoir Research Articles

Lake Trout Consumption and Recent Changes in the Fish Assemblage of Flaming Gorge Reservoir

Abstract Bioenergetics modeling was used to quantify the consumption dynamics of lake trout Salvelinus namaycush in Flaming Gorge Reservoir, Utah–Wyoming. Analysis of diet and population estimates of different size-classes of lake trout indicated that kokanees Oncorhynchus nerka made up the greatest proportion of prey biomass. Examination of growth rates of forage fish and predator–prey size ratios indicated that Utah chub Gila atraria were more vulnerable than kokanees to lake trout predation. Utah chub grow slower than kokanees and thus were susceptible to piscivores over a longer age span. We conclude that kokanees will make up an even larger proportion of the pelagic fish assemblage of Flaming Gorge Reservoir in future years.

Spawning-Site Selection by Kokanee along the Shoreline of Flaming Gorge Reservoir, Wyoming-Utah

We assessed spawning-site selection by kokanee Oncorhynchus nerka (lacustrine sockeye salmon) in three shoreline areas of Flaming Gorge Reservoir, Wyoming–Utah, where they were known to spawn, Kokanee selected shale particles 10 cm in length or less on slopes of 21–40° for spawning; there was no apparent selection for water depth, The three spawning areas were unique among 26 potential spawning sites in the reservoir due to their steep slopes and the abundance of small, loose shale particles present. Protecting these three spawning areas from alteration and minimizing water level drawdown during winter are suggested as management alternatives to maintain recruitment of kokanee from shoreline spawning areas in Flaming Gorge Reservoir.

Battle against extinction: native fish management in the American west: ed W. L. Minckley & J. E. Deacon, (University of Arizona Press), ISBN (hardback) 0 8165 1221 3, price US$40.00, 1991, 519 pp, indexes

In 1961 the Green River was poisoned and its native fishes killed so that the new Flaming Gorge Reservoir could be stocked with non-native game fishes for sportsmen. This incident was representative of water management in the West, where dams and other projects have been built to serve human needs without consideration for the effects of water diversion or depletion on the ecosystem. Indeed, it took a Supreme Court decision in 1976 to save Devils Hole pupfish from habitat destruction at the hands of developers. Nearly a third of the native fish fauna of North America lives in the arid West; this book traces their decline toward extinction as a result of human interference and the threat to their genetic diversity posed by decreases in their populations. What can be done to slow or end this tragedy? As the most comprehensive treatment ever attempted on the subject, Battle Against Extinction shows how conservation efforts have been or can be used to reverse these trends. In covering fishes in arid lands west of the Mississippi Valley, the contributors provide a species by species appraisal of their status and potential for recovery, bringing together in one volume nearly all the scattered literature on western fishes to produce a monumental work in conservation biology. They also ponder ethical considerations related to the issue, ask why conservation efforts have not proceeded at a proper pace, and suggest how native fish protection relates to other aspects of biodiversity planetwide. Their insights will allow scientific and public agencies to evaluate future management of these animal population and will offer additional guidance for those active in water rights and conservation biology.

Sediment transport and channel characteristics of a sand‐bed portion of the green river below flaming gorge dam, Utah, USA

AbstractThe Green River is a major tributary of the Colorado River with a drainage area of 115 770 km2 in Colorado, Utah and Wyoming. The influence of Flaming Gorge Dam on sediment transport and the potential for future channel change were studied using comparative analysis of historical aerial photographs from 1952 to 1987 and geographical information systems, published sediment (1951‐86) and discharge (1965‐87) records, and sediment data collected during 1986‐8. Since the closure of the dam in 1964, new equilibrium channel widths were apparently achieved by 1974 in the reach 161‐279 km below Flaming Gorge Reservoir and by 1981 in the reach 465‐509 km below the reservoir. Recent high flows have resulted in an increase in average channel width in both reaches as measured on aerial photographs taken in 1986 and 1987. Sediment data from US Geological Survey gauges on the Green River and its primary tributaries and three sites established on the Green River for this study suggest that bed material sediment transport in the Green River has now attained a quasi‐equilibrium, with the river transporting just the load supplied to it. The potential for future channel changes exists, as evidenced by the response of the channel (i.e. channel widening) to the increased flows during 1983, 1984 and 1986. Future adjustments in channel characteristics should be limited to responses to changes in discharge and sediment supply and transport in the basin.

Zooplankton Density in Flaming Gorge Reservoir, 1965 to 1966 and 1983 to 1984

Zooplankton Density in Flaming Gorge Reservoir, 1965 to 1966 and 1983 to 1984

Influence of Habitat Availability on Spawning Site Selection by Kokanees in Streams

Abstract Spawning sites of kokanees Oncorhynchus nerka in two tributaries to Flaming Gorge Reservoir, Wyoming–Utah, were described. Water depth and current velocity at spawning sites in Sheep Creek (mean wetted width, 8.4 m) and the Green River (mean, 68 m), as well as available habitat in the reaches of the streams used for spawning, were measured in 1985. Modal water depths at redds differed between the two streams, whereas modal current velocities at redds were similar despite substantial differences in available habitat. The data indicate that habitat use curves illustrate kokanee spawning site distributions in a more realistic manner than habitat selection curves that incorporate both habitat use and habitat availability in their computation.

Diet Overlap among Zooplanktophagous Fishes in Flaming Gorge Reservoir, Wyoming-Utah

The use of zooplankton by rainbow trout Salmo gairdneri, kokanee Oncorhynchus nerka, Utah chub Gila atraria, and white sucker Catostomus commersoni was assessed in 17,000-hectare Flaming Gorge Reservoir. Diet overlap among the four fish species was indicated by the selection of zooplankton species and size by the fishes. Competition for food between rainbow trout and the other species is probably a factor that limits rainbow trout stocking success.

Downstream effects of Flaming Gorge Reservoir on the Green River, Colorado and Utah

The Green River is one of the principal tributaries in the Colorado River basin and drains 44,700 m 2 in Wyoming, Colorado, and Utah. Since October 1962, flows of the Green River have been regulated by Flaming Gorge Reservoir, which is located 412 river miles upstream from its confluence with the Colorado River. Mean annual runoff has not been affected by the reservoir. The duration of the relatively large discharges that transport most of the annual sediment load, however, has decreased significantly. As a result, the mean annual sediment discharge has decreased by 54% to 3.21 × 10 6 tons from 6.92 × 10 6 tons at the Jensen gage located 105 river miles downstream from the reservoir and by 48% to 8.83 × 10 6 tons from 17.0 × 10 6 tons at the Green River, Utah, gage located 290 river miles downstream from the reservoir. Sediment supply to I he channel equals the annual transport within a relatively short distance, 68 river miles, downstream from the reservoir. Downstream from river mile 166, the supply of sediment from upstream plus tributary inflow exceeds the transport of sediment by ∼5.4 × 10 6 tons per year on an average. The quasi-equilibrium that appears to have existed prior to the reservoir no longer occurs along a majority of the Green River. In response to the reduced peak discharges, the bankfull channel width of the Green River has decreased by ∼10%. Adjustment of the channel to decreased peak flows and altered sediment loads is nowhere complete. At present, it appears that a century or more will be required for the Green River to adjust to the effects of Flaming Gorge Reservoir.

Phosphorus release from the sediments of Flaming Gorge Reservoir, Wyoming, U. S. A.

(1984). Phosphorus release from the sediments of Flaming Gorge Reservoir, Wyoming, U. S. A. SIL Proceedings, 1922-2010: Vol. 22, No. 3, pp. 1457-1464.

APPLICATION OF MULTISPECTRAL DIGITAL IMAGERY TO THE ASSESSMENT OF PRIMARY PRODUCTIVITY IN FLAMING GORGE RESERVOIR

ABSTRACT In support of the Bureau of Reclamation effort to manage eutrophication trends in Flaming Gorge Reservoir, Utah and Wyoming, remote sensing studies employing multispectral digital imagery were undertaken. Specifically, the imagery was used to extrapolate point measurements of chlorophyll concentration and light penetration to characterize conditions throughout the reservoir. In 1981 and 1982, aircraft and satellites acquired digital imagery of the reservoir concurrent with surface sampling. Sampling stations were identified within the imagery and the digital values at these points recorded. The surface measurements of chlorophyll and light penetration were regressed against the digital image values to obtain predictor equations for these indicators of primary productivity. The equations were then applied to the images of the whole reservoir to obtain maps of the distribution of chlorophyll and light penetration. A unique set of equations was defined for each data-gathering date. The favorable res...

Life History of the Colorado Squawfish, Ptychocheilus lucius, and the Colorado Chub, Gila robusta, in the Green River in Dinosaur National Monument, 1964–1966

Abstract Investigations of the ecology and life history of the Colorado squawfish, Ptychocheilus lucius, and the Colorado chub, Gila robusta, in the Green River in Dinosaur National Monument, Colorado-Utah, were conducted from May 1964, to October 1966. A total of 1,469 squawfish and 2,393 chubs was collected with gill nets, seines, fry gear, and an electric shocker. The operation of Flaming Gorge Reservoir (46 miles above the Monument) has reduced the range of these two species in this area. Age and growth determinations were made from scales from 182 squawfish and 333 chubs. Both species grew slower in years after reservoir operation began (1963–1965) than before (1958–1962); this reduction in growth rate was related to the alteration of seasonal stream-temperature pattern caused by these operations. The bonytail form of the Colorado chub grew faster than the roundtail form. Length-frequency analyses of young squawfish and chubs described seasonal growth of the first three year-classes and provided evid...