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Document Type

Thesis - University Access Only

Award Date

1992

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

First Advisor

David W. Willis

Abstract

Walleyes Stizostedion vitreum and saugers S. canadense were collected from White Earth Bay, Van Hook Arm, and Snake Creek Bay of Lake Sakakawea, North Dakota, from May to October, 1991. Food habits were determined and compared among sites within species and compared between species within sites. The occurrence of empty stomachs encountered ranged from 18-93\ for walleyes and 31-100\ for saugers. Food habits were evaluated using the relative importance index. Rainbow smelt Osmerus mordax were the most important prey throughout the reservoir; however, seasonal importance of rainbow smelt varied among sites. Rainbow smelt importance decreased from the lower to upper end of the reservoir. Percid diets became more diverse from August to October when young-of-the-year (YOY) prey fishes became available. Percids preyed on YOY paddlefish Polyodon spathula during October at White Earth Bay. Size of prey increased with increased percid length, but was highly variable. The resource overlap index was used to identify the potential for intra- and interspecific competition. Walleye and sauger resource overlap values were variable among length groups for each species. Resource overlap values were highest for length groups that were adjoining at Van Hook. Resource overlap values were variable for walleyes and saugers of similar lengths groups. In general, food habits during a specific month were similar for percids of all lengths within sites. No negative effects of competition were noted during this study. Population structure and dynamics were evaluated to determine if spatial and temporal variation existed. Walleye and sauger size and age structures were different among sites and months. Catch rates, condition, and size structure were high in spring, decreased throughout the summer and increased in autumn. Walleye growth and condition were different among sites. Sauger condition was different among sites, but growth was not significantly different. Although some spatial variation existed for walleyes and saugers, percid populations should be managed as a single fishery. The presence of temporal variation indicates that standardized sampling is important for assessment of population changes.

Library of Congress Subject Headings

Walleye (Fish) -- Food
Sauger -- Food
Fishes -- North Dakota -- Sakakawea, Lake -- Food

Description

Includes bibliographical references (page 90-97)

Format

application/pdf

Number of Pages

115

Publisher

South Dakota State University

Rights

Copyright © 1992 Steven W. Mero. All rights reserved.

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