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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

Charles R. Berry

Abstract

Hybrids between walleye Stizostedion vitreum vitreum and sauger S. canadense in Lake Sakakawea, North Dakota were identified electrophoretically using the species-specific marker malate dehydrogenase. Hybrids represented 10% of 279 percids analyzed. Univariate analysis indicated that counts for eight meristic characters of hybrids were intermediate to, but not significantly different (P ≥ 0.05) form those of parental species, because the respective counts overlapped broadly. Discriminant analysis revealed five of 14 morphometric characters contributed significantly (P ≤ 0.05) to multivariate discrimination among Stizostedion species and hybrids. Using those characters selected by discriminant analysis, 188 of 259 (73%) specimens were correctly classified. Meristic counts and morphometric measurements offer little promise as diagnostic tools for identification of Stizostedion species and their associated hybrids from sympatric populations. Horizontal starch gel electrophoresis and histochemical staining procedures were used to analyze allozyme variation in sauger collected from three locations in Lake Sakakawea. Of the 17 enzymes examined, no genetic polymorphisms were observed. Sauger populations from the three locations were similar for 14 morphometric and eight meristic characters. Discriminant functions analysis correctly classified 65 of 127 (51%) specimens among sites. Genetic and morphological homogeneity of sauger among sampling locations suggested that no distinct stocks were identified. Horizontal starch gel electrophoresis and histochemical stains were used to analyze allozyme variation among subpopulations of walleye collected form three locations in Lake Sakakawea and Lake Oahe, South Dakota. Of the 30 enzyme and protein loci screened, only malate dehydrogenase-3, alcohol dehydrogenase-1, general protein-3, and isocitrate dehydrogenase-1 were polymorphic. Chi-square contingency analyses showed genetic homogeneity among Lake Sakakawea walleye populations and between Lake Sakakawea and Lake Oahe walleye populations. Genetic variation was estimated for Lake Sakakawea walleye from average heterozygosity (9.2-10.7%) and percent polymorphism (20.0-26.7%). Walleye populations from the three locations in Lake Sakakawea were similar for 14 morphometric and eight meristic characters. Discriminant function analysis correctly classified 61 of 105 (58%) specimens among the sites in Lake Sakakawea. When Lake Sakakawea walleye were compared to Lake Oahe walleyes, discriminant function analysis correctly classified 112 of 127 (88%) specimens using morphometric characters. Meristic values of walleyes from both reservoirs were not significantly different. The homogeneity of allele frequencies, low level of genetic variation, and morphological homogeneity among Lake Sakakawea walleyes may be related to sampling during non-reproductive periods.

Library of Congress Subject Headings

Stizostedion
Stizostedion -- Morphology
Electrophoresis
Fishes -- North Dakota -- Sakakawea, Lake

Description

Includes bibliographical references (page 63-70)

Format

application/pdf

Number of Pages

83

Publisher

South Dakota State University

Rights

Copyright © 1992 Neil E. Ward, III. All rights reserved.

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