Author Type

Graduate Student

Date of Award

Spring 4-7-2026

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

April 2026

Department

Biological Sciences

College Granting Degree

Charles E. Schmidt College of Science

Department Granting Degree

Biological Sciences

Degree Name

Doctor of Philosophy (PhD)

Thesis/Dissertation Advisor [Chair]

Sarah Milton

Abstract

Green sea turtles are impacted by their interactions with recreational fishing piers, but how these interactions affect their diet, behavior, and hooking risk remains poorly understood. The objective of this study was to characterize and quantify interactions between juvenile green turtles (Chelonia mydas) and a recreational fishing pier in southeast Florida. The goals were to evaluate how proximity to the pier influences turtle diet, behavior, and incidental hooking. We compared pier-hooked turtles with individuals captured on an adjacent reef and at a control site lacking a nearby pier. Dietary preferences were assessed using nitrogenous blood analytes and stable isotope analysis. Nitrogenous blood analyte values were strongly influenced by body size, with blood urea nitrogen concentrations elevated in pier-hooked turtles. Stable isotope analysis revealed no differences inδ¹³C values among capture locations, whereas δ¹⁵N values were significantly enriched in pier-hooked turtles. These findings suggest opportunistic supplementation of natural diets at the fishing pier, with smaller turtles potentially relying more heavily on protein-rich, anthropogenic food sources than larger, more herbivorous conspecifics. Fine-scale movements were examined using an acoustic receiver array deployed around the pier. Turtles exhibited diel shifts in habitat use, occupying hardbottom habitats during daylight hours and associating strongly with a nearby artificial reef at night. The use of artificial reefs suggests that multiple habitat types should be evaluated to understand site specific behaviors of green turtles. Fishing hooks and associated gear recovered from pier-hooked turtles were classified and compared with gear used by recreational fishers at the pier. Small J and circle hooks, which were most commonly used by fishers, were also most frequently recovered from hooked turtles. Although no seasonal shifts in bait type were observed, fishing effort peaked during summer months and was positively correlated with the number of turtles hooked. Future conservation and management efforts should prioritize reducing interactions between fishers and green turtles by limiting turtle access to fisher-derived protein, implementing bycatch reduction and mitigation strategies that account for temporal variability in turtle presence and fishing effort, and incorporating long-term spatial planning to minimize the placement of fishing piers near turtle-preferred natural and artificial habitats.

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