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Document Type

Research

Keywords

Larval Walleye, Stizostedion vitreum vitreum

Abstract

Larval walleye were collected in Clear Lake, Iowa, during May and June, 1972, to determine their food habits, growth and distribution while in the pelagic stage. Larvae were pelagic until early June, and then moved into littoral areas of the lake. During the pelagic stage, larvae exhibited vertical movement toward the surface at night and to deeper zones during the day. Mean total body length of larvae was 9 mm on May 13 and 32.6 mm on June 8. Feeding commenced when larvae reached 9 mm in length. Cladocera and Copepoda comprised 94.6 percent of the total number of food organisms consumed by 444 larvae. Dominant Copepoda used as food were Cyclops and Diaptomus. Daphnia was the predominant Cladocera and individual food organism consumed. Electivity indices showed larvae positively selected Cyclops and Diaptomus, but selected Daphnia in proportion to its abundance. Mean lengths of Daphnia and Cyclops in larvae stomachs were consistently larger than mean lengths of these organisms in plankton samples, suggesting size selection in feeding.

Publication Date

December 1974

Journal Title

Proceedings of the Iowa Academy of Science

Volume

81

Issue

4

First Page

143

Last Page

149

Copyright

© Copyright 1974 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf

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