Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Steven Murawski, Ph.D.

Committee Member

Christopher Stallings, Ph.D.

Committee Member

Linda Lombardi, Ph.D.

Keywords

Growth, Mortality, Oil spill, Otolith

Abstract

The Deepwater Horizon (DWH) oil spill had catastrophic impacts on aquatic organisms in the Northern Gulf of Mexico (GoM). Longline gear was used to sample demersal fish species at 344 locations distributed throughout the GoM in the seven years following DWH. Sampling was accomplished deploying 450-500 baited hooks per station in depths ranging from 20-600 m. Using data from these surveys, I analyzed the length and age frequency, condition, growth, and mortality rates of Golden Tilefish (Lopholatilus chamaeleonticeps) throughout the GoM. Demersal habitat use and apparent high contaminant levels in Golden Tilefish makes them potentially vulnerable to oil spills such as DWH. Therefore, comparing population resiliency by analyzing rates of growth and mortality is an obvious methodology for understanding the effects of anthropogenic perturbations and how vital rates vary spatially. Comparisons were also made by country of origin in order to establish a baseline dataset for the southern GoM. Although there is spatial and temporal variation in some length distribution, condition, and growth metrics, other metrics show no difference among Golden Tilefish by country of origin, site location relative to the DWH spill perimeter, and in pre- and post-spill comparisons. Golden Tilefish grow slightly faster off Mexico than in the Northern GoM, however the total mortality rate (Z), determined via catch curve analysis, was higher off Mexico than in the United States. Growth curves fit to length-at-age data from the DWH spill site and all other US sites post-spill showed slight differences, although those differences decreased in pre- and post-DWH spill site comparisons. Although the total mortality rate was much higher in fish from the DWH spill perimeter compared to all other US sites, there was no discernable difference in Z occurred pre- vs. post-spill. Thus, any differences in growth and mortality observed in post-spill fish from the DWH spill perimeter compared to post-spill fish from elsewhere in the US appear to be endemic to the northeastern Gulf of Mexico. While further study is needed to analyze the impacts from oil exposure on eggs and larvae on population demographics, Adult Golden Tilefish appeared to be resilient against DWH oil exposure.

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