Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department / School

Natural Resource Management

First Advisor

Nels H. Troelstrup, Jr.

Abstract

Benthic invertebrates are an important resource for aquatic consumers and should be considered in management of sportfish populations as a factor influencing fishery health. Our study seeks to draw a relationship between invertebrate prey availability and the Channel Catfish Ictalurus punctatus fishery of western South Dakota through diet analysis, but invertebrate surveys in the area have not focused on invertebrates as a prey source. Our objectives were to characterize patterns in availability of the invertebrate prey base in five major river basins, and to evaluate the effects of availability on Channel Catfish prey selectivity and condition. Invertebrates were collected at 47 stream sites between the summers of 2015 and 2016, but Channel Catfish were collected only at the 23 mainstem sites. Seventy-four families and 181 genera of invertebrates were encountered. Insecta was the richest taxonomic group, with 162 genera. Diptera, which was composed of 11 families and 83 genera, was the most diverse order. The most numerically abundant genus collected was Cheumatopsyche spp. (Trichoptera: Hydropsychidae), comprising 23.6% of all individuals. Clinging genera contributed 42.1% of the biovolume by habit guild, and biovolume of collector-filterers was the highest of all functional feeding groups (39.2%). Overall, prey biovolume was not uniform. The Grand and Cheyenne had a decreasing longitudinal trend in biovolume, while the Bad showed an increasing trend. There were no consistent patterns in biovolume for the Moreau or White, but sites in all basins with high biovolume typically also had a high abundance of clingers, which require stable surfaces for attachment. Across all sites, Hydropsychidae, Simuliidae, and Chironomidae had the highest biovolumes (35.8 mL, 8.3 mL, and 8.1 mL, respectively), and were also among the most important prey families in each basin (Prey-Specific Index of Relative Importance, %PSIRI). These families also tended to be preyed upon in greater proportion than their availability in the environment (Chesson’s selectivity index, α). Patterns in condition within and among basins mirrored patterns in prey biovolume in the Grand, Cheyenne, and Bad Rivers, indicating that availability may be driving condition. These results are important because two of the preferred prey families, Hydropsychidae and Simuliidae, are clingers, and the non-uniformity in biovolume of this habit guild among sites suggests that stable habitats are limiting abundance. The links drawn between Channel Catfish and their prey can be used by biologists to focus management activities on projects that will enhance the invertebrate prey base that Channel Catfish use, such as the restoration of riparian areas to increase instream structure, or the placement of artificial stable substrates.

Library of Congress Subject Headings

Channel catfish -- Food -- South Dakota.
Stream invertebrates -- South Dakota.

Description

Includes bibliographical references (pages 93-105)

Format

application/pdf

Number of Pages

114

Publisher

South Dakota State University

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Rights Statement

In Copyright