Date Awarded

2015

Document Type

Thesis

Degree Name

Master of Science (M.Sc.)

Department

Virginia Institute of Marine Science

Abstract

The Striped Bass (Morone saxatilis) is an anadromous finfish that supports a lucrative fishery along the Atlantic coast of the United States and serves as a vital component of estuarine food webs. Once Striped Bass stocks were restored after crashing in the late 1980s, abundance skyrocketed to record levels. Over the past decade however, abundance has steadily declined, concurrent with an outbreak of mycobacteriosis. Disease prevalence is currently >50%, and previous research has demonstrated diseasepositive fish exhibit slower growth and increased natural mortality compared to diseasenegative fish. The purpose of this research was to provide a contemporary description of Chesapeake Bay Striped Bass reproductive metrics, which have not been thoroughly described since the stock crashed but before it rebounded. Additionally, the effects of mycobacteriosis on reproductive output were assessed via egg-per-recruit analysis. Female Striped Bass were collected from the York, James, and Rappahannock Rivers and the mainstem of the Chesapeake Bay from 2003-2013. Oocyte development, maturity, oocyte size, fecundity, the gonadosomatic index, and oocyte dry mass were fit to regression models against age, length, or weight in order to determine the influence of month, year, disease prevalence, and female pre-spawning condition. The best fitting models for maturity-at-age and fecundity-at-length were combined with a growth model and estimates of fishing mortality and disease progression to create egg-per-recruit models that simulated the effects of decreased growth and increased natural mortality due to disease on the lifetime reproductive output of Chesapeake Bay Striped Bass. Lower age-at-maturity was seen for disease-positive fish compared to disease-negative fish, but no other reproductive metrics were affected. The increased natural mortality caused by the disease was shown to appreciably reduce reproductive output. This study provides critical biological metrics that can be used to inform future studies and reveals the extent to which mycobacteriosis can influence Striped Bass population dynamics.

DOI

https://dx.doi.org/doi:10.25773/v5-mdh7-b167

Rights

© The Author

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