HCNSO Student Theses and Dissertations

Defense Date


Document Type


Degree Name

M.S. Marine Biology


Oceanographic Center

First Advisor

David W. Kerstetter

Second Advisor

Amy C. Hirons

Third Advisor

Charles F. Cotton


The pelagic stingray, Pteroplatytrygon violacea, is a bycatch species in the global pelagic longline fishery. However, little research has been conducted on its basic biology, including prey composition, trophic positioning, and habitat utilization. Descriptions of the habitat utilization have largely been through indirect analyses of catch rates in commercial fisheries, which also provided no information on actual behaviors. The first chapter of this thesis will describe the habitat utilization and behavior of four individual pelagic stingrays using electronic tagging technology. Prior diet descriptions were hampered, in part, by low sample sizes and accordingly provided little information on the ecological interactions of these animals. Similarly, the second chapter of this thesis will therefore provide a new diet description for the pelagic stingray using a combined analysis of traditional stomach contents with stable isotope values, thereby addressing both ingestion and assimilation. A more robust study of the trophic dynamics of the pelagic stingray, in conjunction with the description of its habitat utilization, will provide a better understanding of its role within the pelagic ecosystem. Ultimately, the goal is to obtain knowledge of the less economic species with good science so when management approaches shift from species-specific to ecosystem based, the transition will already have known information to change efficiently.



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