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Document Type

Thesis - University Access Only

Award Date

2001

Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science

First Advisor

Charles R. Berry Jr.

Abstract

Prior to this research, no catfish-specific studies had been conducted on the Big Sioux River (BSR) despite the fact that channel catfish Ictalurus punctatus are the most harvested and most preferred gamefish by recreational anglers on the BSR. Some South Dakota catfish anglers have requested regulations that protect trophy channel catfish, but resource managers had insufficient information available for making trophy management decisions. The objectives of this study were to 1) assess channel catfish size structure, relative abundance, condition, growth, age structure, and total annual mortality at the segment scale, 2) delineate longitudinal trends in channel catfish population structure and dynamic rate functions, and 3) make trophy (i.e., 2: 71 0 mm) channel catfish management recommendations. During the summer of 2000, channel catfish were sampled (N = 2,327) from the upper, middle, and lower segments of the BSR. With nearly equal sampling effort among study segments, 67% of the memorable-length channel catfish were captured from the upper segment of the river. Size structure, quantified as proportional stock density (PSD), relative stock density of preferred-length fish (RSD-P), and relative stock density of memorable-length fish (RSD-M) was significantly higher (P < 0.05) in the upper segment when compared to the middle segment and lower segment of the BSR. Growth, quantified as mean length at age, was significantly different among segments for age-2 through age-9 fish (P < 0.0045), and was significantly faster in the upper segment than in the middle and lower segments. Stock-length CPUE did not differ among segments (P = 0.14), but among-segment differences in memorable-length CPUE approached significance (P= 0.07). Relative stock density of preferred-length fish (RSDP) was higher at sites with low stock-length CPUE (r = -0.8071, P = 0.0001) and growth was faster at sites with low stock-length CPUE (r = -0.6821, P = 0.0001). Stock-length CPUE was higher at sites that had fewer summer discharge events exceeding 10 times median flow during the period from January 1, 1990 thru September 30, 1998 (r = -0.753, P = 0.001 ). Fisheries Analysis and Simulation Tools (FAST) was used to model the effect of potential length regulations on the abundance of memorable-length fish in the upper and lower segment of the BSR. Models predicted that slow growth rates would limit the abundance of memorable-length fish in the lower segment of the BSR regardless of regulation, but in the upper segment of the BSR length regulations could be used to increase memorable-length fish abundance, especially if exploitation rates increase. Using these research findings, resource managers can address angler concerns over trophy catfish sustainability with population data and predictive models.

Library of Congress Subject Headings

Channel catrish -- Big Sioux River (S.D. and Iowa)
Fish populations -- Big Sioux River (S.D. and Iowa)

Description

Includes bibliographical references (page 96-103)

Format

application/pdf

Number of Pages

124

Publisher

South Dakota State University

Rights

Copyright © 2001 Daniel J. Kirby. All rights reserved.

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