Recent research confirmed white shark (Carcharodon carcharias) nursery habitat off Long Island, New York; however, additional research is required to determine the habitat use and fine-scale movements of young-of-the-year and juvenile white sharks within this nursery. Between 2016 and 2019, twenty-five white sharks were fitted with satellite and acoustic tags to better define habitat use. Individuals exhibited horizontal movements parallel to Long Island’s southern shoreline and coastal New Jersey. Log-likelihood chi-square analyses determined preference for water column depth, SSTs, sea surface salinities, and chlorophyll a concentration. Vertical analysis of diving behavior revealed swimming behavior primarily in the upper 20 m of the water column, in temperatures between 18°C and 20°C. Generalized additive mixed modeling suggested SSTs above 20.5°C affected dive depth. These results can help improve characterization of essential fish habitat for young white sharks and provide data to determine the species’ susceptibility to anthropogenic activities. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Dyer Island is thought to host one of the most abundant populations of white sharks on the planet; this is often credited to the large (55 – 60,000) Cape fur seal colony at Geyser Rock. Yet relatively little work has ever been produced from the area. This may be attributed to the harshness in its location as a study site, exposed to wind and swell from west to east which limits research periods. This study accounts for over 220 hrs of manual tracking at Dyer Island with a further 68 added from the inshore shallow areas of the bay. Sharks focused their movements and habitat use to reefs or channels that allowed access to Cape fur seals. Movement- Based Kernel Estimates (MKDE) were used to compute home range estimates for shark movements through and around the heterogeneous structures of Dyer Island and Geyser Rock. Inshore two core areas were revealed, one being the major reef system at Joubertsdam and the other at a kelp reef where the tracked shark had fed on a Cape fur seal. At Dyer Island one core area was identified in a narrow channel, ‘Shark Alley’, here a second tracked shark foraged for entire days within meters of rafting Cape fur seals. Rate of Movement (ROM) and Linearity (LI) of tracks were low during daytime and movements were focused around areas such as Shark Alley or other areas close to the seal colony before moving into deeper water or distant reefs with higher rates of ROM and LI at night. If moonlight was strong foraging would take place to the south of Geyser Rock but with higher ROM and LI than observed during the day. Foraging patterns in this study contrast studies from other sites in South Africa and home range and activity areas were comparatively much smaller than observed in Mossel Bay. It has been established that several known white sharks forage at Dyer Island and the other studied aggregation sites, such differences in foraging would suggest that they are able to adapt their foraging behaviour to suit the environment they are in; making them site specific in their foraging ecology. Both satellite and acoustic telemetry are revealing aggregation hotspots of white sharks in South Africa. It is important that such information is used to assist the recovery of the species which has been protected since 1991, yet is rarely considered in planning of coastal developments. / Dissertation (MSc)--University of Pretoria, 2012. / Zoology and Entomology / MSc / Unrestricted