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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science

First Advisor

Walter G. Duffy


bioenergetics, smelts, rainbown smelts, south dakota, lake oahe


Lake Oahe was formed by closure of Oahe Dam on the Missouri River by the U.S. Army Corp of Engineers in August, 1958. The reservoir reached full pool in December of 1967 and extends from Pierre located in North-central South Dakota into the southern third of North Dakota near Bismarck (June 1974). Lake Oahe is one of six mainstem reservoirs on the Missouri River and, in area, is the second largest reservoir in the United States (Duffy 1988). Lake Oahe is classified as a federally operated multi-purpose reservoir providing water storage for release during dry summer months to facilitate commercial barqe traffic downstream, irrigation for the upper Great Plains, water for human consumption, hydroelectric power, and recreation. Lake Oahe covers 152,000 hectares at maximum pool, which is 493.8 m above mean sea level. Water levels are expected to fluctuate within a maximum range of 24.4 m and an average fluctuation of 3.8 m annually. Minimum operating pool has been established at 469.4 m above mean sea level. (June 1974). Closure of the dam changed the ecology of the Missouri River from a silt laden river into a deep, oligotrophic, cold water reservoir. The biological community of the river changed with the creation of new habitats. Reduced growth and reproduction were noted for many native species as well as a reduction in the number of fish species in the river (Duffy 1988). Little work has been conducted studying the trophic status of Lake Oahe since its impoundment twenty-five years ago. The effect of reservoir aging on the growth and population dynamics of fish species and communities is poorly understood for Lake Oahe as well as other reservoirs. Initial studies on Lake Oahe were conducted by the u.s. Fish and Wildlife Service, North Central Reservoir Investigations Team. Production of fish-food biota in Lake Oahe increased substantially during its first years while the lake inundated terrestrial areas (Aggus 1971). Rapidly rising waters submersed terrestrial vegetation increasing invertebrate food supplies (Ploskey 1985). Changes in trophic status may be inf erred from increased or decreased growth rates and changes in fish diets. Nelson (1974) evaluated growth of thirteen species of fish and suggested that productivity was increased by the inundation of vegetation as Lake Oahe filled. Since these data were collected, it is believed that the limnology of Oahe has changed. The fish community has changed substantially with the deepening of the river and stockings of prey and predator fish. Fish growth has declined and has been attributed to reduced productivity of lower trophic levels (Bensen 1968).

Library of Congress Subject Headings

Smelts -- South Dakota -- Oahe, Lake


Includes bibliographical references (page 89-96)



Number of Pages



South Dakota State University


Copyright © 1992 Chris Edward Freiburger