Understanding the movements, site fidelity and behaviour of mesopredator species is essential for understanding their basic ecology, defining their role in ecosystems and assessing the potential effects of human impacts on populations. This study investigated the movement patterns of adult Port Jackson sharks (PJs; Heterodontus portusjacksoni), a highly abundant mesopredator in temperate marine ecosystems. Acoustic tracking data from PJs were collected between 2012 and 2014 to monitor shark movements within the Jervis Bay Marine Park and examine sex-specific differences in space use and site fidelity. We found that PJs show extremely high levels of site fidelity at their breeding aggregation sites, with males showing a significantly higher level of site fidelity than females.  On average, 98% of all male detections occurred at their preferred location in Jervis Bay compared to 83% for female PJs. There was no correlation of site fidelity level and total length of the individuals for either sex, suggesting site fidelity is not significantly influenced by age. Further, intra-specific variation was observed in the spatial and temporal patterns of movement within Jervis Bay, with some sharks displaying more crepuscular detection patterns, while others appearing more diurnal. The findings of this study highlight the importance of considering individual variation in behaviour, which may be driven by a combination of demographic factors and environmental variables. In addition, the high levels of site fidelity detected for PJs in this study may be a strategy used by individuals to increase their reproductive success through increased familiarity to habitat, food resources and conspecifics.