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Author ORCID Identifier
Campus-Only Access for One (1) Year
Doctor of Philosophy (PhD)
Marine Sciences and Technology
Year Degree Awarded
Month Degree Awarded
Behavior and Ethology | Ecology and Evolutionary Biology | Marine Biology
Sharks present a myriad of challenges for fisheries managers as highly mobile, K-selected species. Our knowledge of shark spatial ecology varies widely by species and region, presenting further challenges for resource managers. Globally, most large-bodied shark species have experienced dramatic declines driven primarily by overfishing, through targeted or bycatch mortality, as well as habitat degradation. However, after decades of careful conservation-based management, a number of species in the United States are showing signs of slow recovery. This puts the state of shark conservation in the United States at an interesting crossroads where managers must grapple with the paucity of ecologically important data for many species and regions, while navigating increasing conflicts between sharks and other ocean user groups, namely anglers. In this dissertation, I address these knowledge gaps by combining multiple data streams: spatial data from acoustic telemetry, visual survey data, and social science survey data with novel analytical techniques, including network analysis and machine learning. In Chapter 2, I define residency, habitat use, and intra-specific interactions for four shark species within Buck Island Reef National Monument, a marine protected area in St. Croix, U.S. Virgin Islands. It is the first study of shark spatial ecology in St. Croix, and significantly advances our knowledge of shark ecology in the data-poor U.S. Caribbean. In Chapters 3-5, I address emerging conflicts between sharks and recreational anglers through shark depredation, using great hammerhead sharks (Sphyrna mokarran) depredating Atlantic tarpon (Megalops atlanticus) as a case study. I characterize space use for both species at a fine and broad scale to determine the drivers of depredation and potential migratory coupling. In addition, I surveyed anglers to quantify their responses to depredation, revealing that increased depredation frequency results in an increased likelihood of retaliation against sharks. In the final chapter, I synthesize my results and offer next steps to advance our knowledge of shark ecology in St. Croix and the study of shark depredation in recreational fisheries. This dissertation highlights the utility of multifaceted approaches to addressing conservation conflicts and fills significant knowledge gaps that exist in the changing seascape of shark conservation.
Casselberry, Grace A., "MULTIFACETED APPROACHES FOR ADDRESSING THE CHANGING SEASCAPE OF SHARK CONSERVATION" (2023). Doctoral Dissertations. 2966.
Available for download on Sunday, September 01, 2024