Document Type

Thesis

Abstract

Marine predators, particularly elasmobranch species like bull sharks (Carcharhinus leucas), play crucial roles in maintaining marine ecosystems but face threats due to anthropogenic impacts and global climate change. Management and conservation of these species incorporate an understanding of their movement behaviors and spatial distribution, which is currently understudied for large bull sharks in the Western North Atlantic (WNA). Therefore, this thesis focuses on understanding bull shark movement patterns in the WNA, including pregnant females. We first examine the movement behaviors of bull sharks from 2009 to 2023 using extensive passive acoustic telemetry data from the Bimini Biological Field Station (BBFS) and its collaborators. Network analysis of acoustic detections revealed partial migration, based on the presence of mobile and resident clusters of bull sharks in the WNA, which are theorized to represent behavioral contingents. The presence of contingents is thought to influence the resilience of populations by spreading risk from external threats, but on the other hand may also increase the risk of localized depletion from fishery pressure. Additionally, this research qualitatively examined the movements of pregnant bull sharks. By determining the locations of pregnant individuals during the theorized pupping window, we were able to infer pupping locations and identify differences in the regional dispersal of individuals that gave birth in either the Gulf of Mexico or the Atlantic Ocean. Furthermore, three female bull sharks exhibited site fidelity behavior to waters near Bimini, The Bahamas, as they returned annually following a seasonal migration during both pregnant and non-pregnant periods, suggesting Bimini is a seasonally important area for mature female bull sharks of all reproductive stages. Overall, the findings of this research provide valuable insights into the movement dynamics of bull sharks, which may contribute to conservation and management strategies.

Publication Date

8-17-2024

Handle

http://hdl.handle.net/11122/15528

Download

Share

COinS