Date of Award

Summer 2021

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Kevin Dillon

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Michael Andres

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Frank Hernandez

Committee Member 3 School

Ocean Science and Engineering

Abstract

Gulf Sturgeon (GS), Acipenser oxyrinchus desotoi, are a threatened, anadromous fish species in the northern Gulf of Mexico. Their range is from the Pearl River, LA, in the west to the Suwannee River, FL, in the east with a longitudinal divide at Mobile Bay, AL, creating a western population unit (WPU) and an eastern population unit (EPU). Sturgeon belonging to the WPU exhibit lower abundances, higher mortality rates, and are overall less studied than their EPU counterparts. Notable data gaps for the WPU includes the absence of recent population parameter estimations and confirmed feeding habitat. My thesis aims to reduce our knowledge gaps for WPU sturgeon by estimating population parameters through mark-recapture modelling and describing feeding habitat by stable isotope analysis for GS natal to the Pascagoula River. Pascagoula River GS were captured with anchored gill nets, tagged, and had blood and muscle samples taken between April–November from 2013–2020. Mark-recapture modelling revealed a steadily increasing GS abundance between 2013–2020 and a higher survival than previously estimated for this population, but comparisons with the EPU are difficult. Stable isotope analysis revealed δ13C values of a majority of individuals indicated estuarine/marine feeding. Only young-of-year and age-1 individuals had δ13C values indicative of river feeding, and only some year ones seemed to also feed in the estuary. This project has helped close knowledge gaps that will be important for continued monitoring of the species.

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