Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Fall 2020

Thesis Director

Robert E. Colombo

Thesis Committee Member

Eden L. Effert-Fanta

Thesis Committee Member

Zhiwei Liu

Abstract

Fisheries managers are devoting considerable effort, time, and funding towards limiting the spread of invasive Bighead and Silver (bigheaded) Carp. A better understanding of factors that influence spatial patterns of bigheaded carp reproduction can help fisheries managers prevent their spread. To examine factors that influence spatial patterns of reproduction, we sampled ichthyoplankton using drift nets and larval push nets in three tributaries of the Illinois and Wabash Rivers March-September 2016-2018. We compared relative abundances of bigheaded carp eggs and larvae among tributaries using catch per unit effort (CPUE). Abiotic data were analyzed from individual study tributaries and pooled among tributaries with substantial versus minimal evidence of bigheaded carp reproduction. In total, 5,689 larval bigheaded carps were captured during three sampling seasons. Of the six study tributaries, we captured the most bigheaded carp larvae in the Sangamon River, followed by the Little Wabash, Embarras, Spoon, Mackinaw, and Vermilion Rivers. Based on previous literature, we investigated differences in watershed area, discharge, water temperature, turbidity, and free-flowing stretches of river in our study tributaries. In general, tributaries with greater relative abundance of bigheaded carp eggs and larvae had larger watersheds, greater discharge, lower secchi depths (higher turbidity), and longer free-flowing stretches than those with minimal evidence of reproduction. This study provides a thorough investigation of bigheaded carp reproduction in six large river tributaries and will help fisheries managers better monitor and mediate the spread of these invaders by helping prioritize potential monitoring locations.

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