Addressing data deficiencies in a threatened mobile marine predator

Knowledge of ecological and life-history traits over ontogeny for long-lived migratory marine species is vital to creating effective conservation and management strategies, however these details are often difficult to obtain. Incrementally growing biomineralized structures, such as elasmobranch vertebrae, are metabolically stable and provide the potential to investigate changes in spatial and trophic ecology over ontogeny. In the present dissertation, chemical tracer analysis (delta13C, delta15N, and Delta 14C) and opportunistic sightings data are used to address data deficiencies for a threatened marine predator (white shark, Carcharodon carcharias ).;Prior to the broad application of stable isotope analysis on elasmobranch vertebrae the methodological effect of demineralization on bulk delta 13C and delta15N values was investigated. This study indicated that white and tiger (Galeocerdo cuvier) sharks do not require demineralization prior to analysis, allowing for fine-scale sampling over ontogeny. The age and growth parameters of white sharks off southern Africa were determined using bomb carbon and standard band counting method, revealing individuals are longer lived and slower growing than previously estimated for this region. Due to large variations in the ontogenetic profiles of stable isotopes among individual juvenile white sharks, it is recommended to integrate stable isotope data into a multidisciplinary framework to generate the most reliable data for resource managers. While the isotope values in the vertebrae of sub-adults revealed that individuals in this region have several strategies of habitat use and all individuals use habitat where no protection is currently in place (i.e., pelagic or north of KwaZulu-Natal along the east coast of Africa). Through a meta-analysis of opportunistic sightings and catch records of white sharks in the northwest Pacific Ocean the temporal and spatial distribution patterns of individuals in this region were examined. These data included a large number of pregnant females and indicated the relative abundance of white sharks is relatively stable.;Through chemical tracer analysis and opportunistic sighting data this dissertation addressed knowledge gaps in the spatial ecology and life-history characteristics for a threatened species over ontogeny and advances our approaches to generate data to inform management on the ecological and life-history traits for difficult to study species.