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Document Type

Thesis - University Access Only

Award Date

1990

Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science

First Advisor

Charles R. Berry Jr.

Abstract

Overabundant populations of common carp (Cyprinus carpio) and black bullheads (Ictalurus melas) may have a detrimental effect on submerged aquatic plant production and thus waterfowl habitat. The relative impact of small common carp (0.9 kg), large common carp (1.5 kg), and black bullheads ( 0.7 kg) on sago pondweed (Potamogeton pectinatus) production was tested within enclosures located at Sand Lake National Wildlife Refuge, north-central South Dakota. Three enclosures of each treatment (fish type) were stocked at a rate of 675 kg/hectare; three enclosures served as controls and did not receive fish. Macrophyte biomass, water turbidity, and fish food habits were monitored for 60 d after plant emergence in both 1988 and 1989. Fish effects on sago pondweed were difficult to ascertain in 1988, due to the lack of adequate plant stands within the control enclosures. In 1989, significant differences were found among treatments (P≤0.01); enclosures confining large common carp, small common carp, and black bullheads had significantly (P ≤ 0.05) lower sago pondweed standing crops compared to the controls. Large common carp reduced sago pondweed biomass by 85% over 60 d. Small common carp and black bullheads also hampered sago pondweed production (54 - 65% reduction in biomass over 60 d). Fishes had no significant effects (P > 0.05) on water turbidity in either year. However, by reducing aquatic plant densities, through uprooting and consumption, fishes such as common carp and black bullheads may indirectly influence turbidity by creating conditions which allow greater mixing by wind. Due to the protected environment of the study sites, which negated wind effects, indirect influences were unable to be evaluated. Macroinvertebrates were the principal food of black bullheads and both size-classes of common carp, comprising 82 - 96% of their diet by weight. Common carp, however, utilized plant matter (14 - 18% by weight) more than the black bullheads (2% by weight). Since no differences in turbidity occurred which could be ascribed to fish activity, and both species of fish fed primarily on invertebrates, the negative impacts of common carp and black bullheads on sago pondweed production appear to be due primarily to physical disturbance by the fishes in search of benthic organisms.

Library of Congress Subject Headings

Potamogeton -- South Dakota
Aquatic plants -- Diseases and pests -- South Dakota
Carp -- South Dakota
Black bullhead -- South Dakota

Description

Includes bibliographical references (page 67-75)

Format

application/pdf

Number of Pages

111

Publisher

South Dakota State University

Rights

Copyright © 1990 Bret F. Kolterman. All rights reserved.

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