Tollgate Islands is an important resting area for one shark species.

There are multiple lines of evidence to support Sand Tiger Sharks regularly and predictably using Tollgate Islands for resting. Evidence includes scientific surveys and acoustic tracking conducted by the New South Wales Department of Primary Industries and Regional Development (Bradford et al. 2025; Otway & Louden 2025), anecdotal observations from the recreational dive industry, and submissions from a citizen science photo-identification database (Sharkbook 2025). Between 2011–2021, 10-year acoustic transmitters were used to track sharks and determine their preferred habitats based on residency rates (Otway & Louden 2025), and this information was used to determine aggregation sites. Nineteen Sand Tiger Shark aggregation sites have been highlighted in eastern Australia (Bradford et al. 2025). These were defined as a site where five or more Sand Tiger Sharks are seen aggregating either continuously or on a predictable seasonal cycle, and all were classified as resting areas for the species based on behavioural observations and habitat use.

Sand Tiger Sharks were observed at Tollgate Islands year-round, however, only juveniles and adult females were recorded in the area. Between 2011–2021, six tagged individuals were detected at Tollgate Islands (474 detections; Bradford et al. 2025). Observed residence periods lasted up to four days. The sharks spent more time in the area during the daylight hours, exhibiting a diurnal usage pattern (Otway & Louden 2025). Juveniles and presumed non-reproductively active females were prevalent during mid-winter to spring, with pregnant Sand Tiger Sharks also occupying the area at this time and likely pupping in the local vicinity (Bradford et al. 2025). Sand Tiger Sharks use the area as part of their annual southerly migration in late spring (Otway & Louden 2025). Scientific surveys confirmed Sand Tiger Sharks were observed swimming close to the seabed in the area, typical resting behaviour for this species, at a mean depth of 19.4 m. The diel patterns in behaviour that the sharks exhibit at these sites are characteristic of Sand Tiger Sharks resting during the day and being active at night (presumably for foraging) (D Harasti pers. obs. 2025). Hovering and milling are also characteristic behaviours of resting Sand Tiger Sharks and comprise the majority of swimming behaviours observed at their main aggregation sites on Australia’s east coast (Smith et al. 2015). When hovering, sharks face into the water current and their tail beats allow them to maintain a stationary position, whereas milling involves slow movements and directional changes generally confined to a particular area within a gutter (Smith et al. 2015).

Anecdotal reports from the recreational dive industry support observations of resting aggregations of Sand Tiger Sharks in this area. Throughout the peak summer season, large aggregations of Sand Tiger Sharks (50+ individuals) have been reported at the ‘Shark Gutter’ at Tollgate Islands (T Bellette pers. comm. 2025). Sharks were observed resting close to the sea floor or inside of caves, with occasional observations of pregnant females (with visible extended abdomen; T Bellette pers. comm. 2025). Between 2005–2025, 84 Sand Tiger Shark sightings were submitted from citizen scientists in the area (Spot a Shark unpubl. data 2025). From these sightings, 22 individuals were identified using photo-identification. Sightings of Sand Tiger Sharks were year-round at the Tollgate Islands, with seasonal peaks between January–March. There is low survey effort in the area due to a lack of dive shops and the relative difficulty in accessing the dive sites. Most citizen scientists are divers who use private boats to go to the area and as such there is less data availability. Still, scientific surveys confirmed up to 20 Sand Tiger Sharks were recorded on a single dive in this area (Bradford et al. 2025).