Semester of Graduation

Fall 2026

Degree

Master of Science (MS)

Department

Department of Oceanography & Coastal Sciences

Document Type

Thesis

Abstract

Monitoring ecological communities is critical to resource management and conservation, yet application of camera-based methodologies is limited in the marine environment due to logistic difficulty. Here, a long-term, remote camera system was introduced to characterize marine fish communities in a case study on those associated with a newly deployed Fish Aggregating Device (FAD) over DeSoto Canyon. This system collected 496 minutes of video across Fall 2024 (37 days) and Spring 2025 (36 days), where relative abundance (MaxN), species richness, and Bray-Curtis dissimilarity among samples were compared at diel, daily, and seasonal scales. Observed taxa included 30 species, 22 genera, and 12 families, dominated by small-bodied and juvenile fishes (Carangidae, Kyphosidae, Balistidae, Monacanthidae). Communities varied significantly among sampling periods, where fall communities displayed greater dissimilarity and volatility, and displayed rapid turnover on daily and diel timescales. Increased sampling frequency detected higher richness and fundamentally different communities from low-frequency sampling. These findings suggest that DeSoto Canyon’s pelagic FAD communities are highly dynamic and characterized by taxa-specific behavior, potential colonization effects, and seasonal events, best characterized by high-frequency sampling.

Highly migratory species, particularly FAD-associated tunas, serve key ecosystem services and supply important global fisheries. Due to the relative novelty of FAD structures in the region, FAD-associated tunas are understudied in the Gulf of Mexico (GoM). This study applied acoustic telemetry to elucidate vertical habitat use, residency, and movement behavior of juvenile tunas (Thunnus atlanticus n = 22, T. albacares n = 2, and Katsuwonus pelamis n = 2) on an eight-buoy FAD array in the northern GoM. Tagged tunas behaved similarly to those in other arrays and FAD-associated HMS globally, displaying a diel trend in vertical habitat use (deep diurnally and shallow nocturnally), hour- to day-scale residencies, and limited inter-FAD movement (n = 5). Movements outside of the array were observed among one skipjack (128 km) and one blackfin tuna (718 km), highlighting connectivity between the array and the eastern GoM. Results suggest alignment in transient behavior among tagged juvenile tunas with FAD-associated individuals worldwide and identify the feasibility of FADs as scientific platforms for ecological study as interest in their deployment grows.

Date

8-20-2026

Committee Chair

Dance, Michael A.

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Saturday, August 19, 2028

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