Theses and Dissertations

ORCID

https://orcid.org/0000-0001-8137-7499

Advisor

Drymon, Marcus

Committee Member

Evans, Kristine O.

Committee Member

Sparks, Eric

Committee Member

Cartwright, John H.

Date of Degree

12-12-2025

Original embargo terms

Immediate Worldwide Access

Document Type

Dissertation - Open Access

Major

Forest Resources (Wildlife, Fisheries & Aquaculture)

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Forest Resources

Department

Department of Wildlife, Fisheries and Aquaculture

Abstract

Evaluation of long-term datasets is essential for management of nearshore, estuarine areas given their heterogeneity and high biodiversity. This is especially true for fisheries, where data deficiency often restricts informed management decisions. The Alabama Department of Conservation and Natural Resources Marine Resources Division (AMRD) has conducted gillnet sampling along the Alabama Gulf Coast since 2001, yielding a long-term dataset capable of assessing resource change responses. The region is highly dynamic, marked by high levels of biodiversity, valuable fisheries, and a population of immature bull sharks (Carcharhinus leucas). However, changing environmental conditions have altered coastal ecosystem dynamics, confounding management efforts. Here, I sought to evaluate habitat dynamics of immature bull sharks and enhance long-term fisheries-independent sampling by addressing three objectives: 1) quantify and map long-term changes in habitat suitability for juvenile bull sharks; 2) formally evaluate the region as bull shark nursery habitat; and 3) implement electronic data collection, visualize data for stakeholder engagement, and evaluate employee attitudes towards electronic data collection for the AMRD gillnet survey. For objective 1, I used boosted regression trees to quantify environmental influences on juvenile bull shark habitat suitability and developed resultant species distribution models from 2003-2005 to 2018-2020. Results showed an almost three-fold increase in mean habitat suitability, with warming waters as the greatest predictor of habitat suitability. For objective 2, I assessed the Alabama coastline as nursery habitat for young-of-year bull sharks according to three shark nursery criteria. Outcomes indicate Mobile Bay routinely provides nursery habitat for bull sharks, but the exact bounds of that habitat vary spatiotemporally, a paradigm shift from traditional static designations. For objective 3, I transitioned the AMRD gillnet survey from paper-based to electronic data collection by developing a Survey123 form, designed a StoryMap to visualize survey data, and evaluated employee perspectives regarding this transition. Results showcase capabilities for modernizing fisheries data collection, enhance data accessibility for stakeholder engagement, and identify gateways and barriers to survey implementation. These outputs provide valuable insight into the spatiotemporal dynamics of bull sharks along the Alabama coast in the face of resource change, as well as support applied fisheries management in the region.

Sponsorship (Optional)

Northern Gulf Institute

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