Master's Theses

Date of Award

Fall 2004

Degree Name

Master of Science (MS)

Department

Biology

Advisor

William Stark

Abstract

White perch (Morone americana) is a temperate bass native to the Atlantic Coast of North America from Nova Scotia to the Carolinas. Although once restricted to the Atlantic Coast, white perch recently have been introduced Into the Ninnescah River in south-central Kansas. White perch were accidentally stocked into Cheney Reservoir in 1992 and have been collected at 13 locations throughout the Ninnescah River since 1999. Introduced populations of white perch often overpopulate, out-compete, and drastically reduce other fish populations. I began a study in May 2002 to 1) determine seasonal distribution and relative abundance of white perch in the Ninnescah River system. 2) determine the age structure and relative growth of white perch in the Ninnescah River system. 3) assess the diet of individuals captured in the Ninnescah River system, and 4) assess the effects of while perch on the native fish community of the Ninnescah River system with emphasis on species of concern. Results from the present study indicate that white perch are seasonally abundant, but probably are not present at all times of the year in the river. A total of 841 white perch was collected in the Ninnescah River system from May 2002 through June 2003. All white perch were collected from the North Fork Ninnescah River, with the exception of one individual collected in the mainstem of the Ninnescah River. Of the 840 collected in the North Fork Ninnescah River, 90% (757) of those individuals were collected upstream of Cheney Reservoir. White perch in the Ninnescah River appear to be relatively short-lived, but exhibit rapid growth compared to populations within the native range of the species. Scale samples from 77 white perch, ranging from 44 to 265 mm in total length, were used to determine age structure. Estimated ages ranged from young-of-year (YOY) to 5 years. YOY and age-1 individuals comprised 78 % of the white perch collected during my study. White perch in the Ninnescah River fed primarily on dipteran larvae. Other aquatic insects also were consumed, but to a lesser extent. However, as white perch grew, their diet shifted from a total dependence on aquatic insects to a mixture of insects and fish, I compared fish communities before and after the invasion of white perch on two spatial scales. I used a Spearman Rank Correlation to compare fish communities before and after the invasion of white perch at the assemblage level and the Morisita's Similarity Index to assess changes in community structure at the basin-wide level. At present, the data seem to indicate little measurable effects of white perch on the native fish community. However, continued monitoring and assessment of white perch and the native fish community of the Ninnescah River system is essential to ensure future patterns or trends do not go undetected.

Rights

Copyright 2004 Eric R. Johnson

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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