Date of Award

Spring 5-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

David T. Gauthier

Committee Member

Holly Gaff

Committee Member

Wolfgang K. Vogelbein

Abstract

Mycobacteriosis was first documented in Chesapeake Bay striped bass (Morone saxatilis) in 1997 after fish exhibited emaciation and skin lesions. Since it was first identified, studies of mycobacteriosis in the mainstem of the Chesapeake Bay (2003-2007) and the Rappahannock River (2005-2012) have shown high disease prevalence and disease-associated mortality. Until this study, no current prevalence data existed from the Rappahannock River, and no published prevalence data existed for the James River, leaving a gap in our understanding of this disease in major Chesapeake Bay tributaries. We began gathering mycobacteriosis prevalence data from an existing survey collecting striped bass from the James and Rappahannock Rivers conducted by Virginia Institute of Marine Science.

During the two years of spring collections, 2,803 striped bass were caught in 2020 and 2,169 in 2021 with 40.8% and 39.9% showing dermal disease, respectively. James River had a higher prevalence with 44.6% of fish caught through electrofishing and 45.0% of gillnet caught fish exhibiting disease compared to 39.5% of fish caught through electrofishing and 35.4% of gillnet caught fish exhibiting disease in the Rappahannock River. Logistic regression was used to examine the effect of various risk factors including age, river, and year class on disease prevalence and severity. Age had a significant positive association with disease while year class had a significant negative association with disease. Fish caught in the Rappahannock River had a significant negative association with disease in some models when compared to being caught in the James River. Disease prevalence increased with increasing age and prevalence was higher than expected in some later year classes after an initial decrease

DOI

10.25777/gd2m-kn82

ISBN

9798819393734

Available for download on Saturday, June 17, 2023

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