Title

Competitive interactions between young-of-the-year smallmouth bass (Micropterus Dolomieu) and round goby (Apollonia melanostomus)

Date of Award

2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biological Sciences

First Advisor

Jeffrey Miner, Dr

Second Advisor

Daniel Wiegmann, Dr

Third Advisor

Rex Lowe, Dr (Committee Member)

Fourth Advisor

Robert Huber, Dr (Committee Member)

Abstract

Fisheries management for the Great Lakes has shifted from an individual species approach to an approach that encompasses community-level processes. This emphasis includes the management of food web structure to optimize the production of sustainable sportfish populations. The maintenance of sustainable top predator populations, like smallmouth bass (Micropterus dolomieu), is expected to promote a resilient and stable fish community (Knight and Vondracek, 1993; Makarewicz and Bertram, 1993). However, the introduction of successful invasive species can have widespread and persistent effects. As the European dreissenids (zebra mussels and quagga mussels Dreissena polymorpha and D. bugensis, respectively) and round goby (Apollonia melanostoma) approach stable densities their impacts are still developing as the aquatic community responds. Whereas fishery managers cannot eliminate these invasive species and restore the community to an earlier state, understanding the modes of interaction among species and quantifying the magnitudes of these interactions will help managers predict responses to invasions and implement strategies to offset negative impacts. Our experiments were designed to specifically assess the interaction between young-of-the-year smallmouth bass and the invasive round goby. Young-of-the-year smallmouth bass were quantified because at this life stage mortality is often high and at this life stage round goby and smallmouth bass experience habitat overlap; both species are located in the epi-benthos. Results from our experiments highlight reduced smallmouth bass growth in the presence of round goby, a change in the smallmouth bass diet (benthic to pelagic prey), eviction of smallmouth bass from the epi-benthos, and continued movement of smallmouth bass at winter temperatures when they should normally enter torpor.