Habitat preferences of Port Jackson Sharks, Heterodontus portusjacksoni, in the coastal waters of Eastern Australia

The habitat preferences of juvenile and adult Heterodontus portusjacksoni and ovipositing females were determined from three locations on the central and southern coast of New South Wales. Adults use shallow coastal rocky reefs in July-November for mating and oviposition, whilst juveniles occupy a seagrass nursery in a large coastal embayment. The sand/reef interface on the lee side of reefs was preferred by both sexes, probably as a refuge against strong water movements. Adult females also preferred rocky gutters when available, possibly as a male avoidance strategy. Preferred oviposition sites were narrow, shallow crevices (single capsules) or deep, narrow crevices (multiple capsules) which afforded protection against mechanical dislocation and/or predation. Juveniles exhibited a strong preference for the seagrass bed edge within a shallow nursery area. The visual complexity of this habitat combined with the juvenile's disruptive colouration may provide a refuge from predation, whilst proximity to the seagrass may provide ease of access for foraging. At a large scale, juveniles preferred areas of moderate slope within the nursery that provided protection from strong water movement. This study highlights the need for quantitative studies addressing habitat preferences and a consideration of use-specific factors to fully understand the selection of habitat by elasmobranchs.