Young scalloped hammerheads gather in groups just off popular swimming beaches in Queensland. A new study shows that Burleigh Beach and Noosa Main Beach in particular provide seasonally used habitats for juveniles. The findings come from drone footage collected by a programme originally designed to protect beachgoers.
84 sightings at nine beaches
The research team led by Maddison Cross analysed footage from Queensland’s SharkSmart programme recorded between September 2020 and December 2024. Across nine beaches in the state’s southeast, they documented 84 sighting events with a combined count of 2,696 sharks. This is not a population census: the same animals could have been recorded again on multiple flights.
Most groups were observed off Burleigh and Noosa. Juveniles predominated there, whereas larger, solitary animals were more frequently seen off North Stradbroke Island. The estimated mean length of the recorded sharks was around 1.09 metres. To assess size, the researchers compared the animals with visible paddleboards, among other references; these are therefore estimates from aerial imagery.
Seasonal groups in small areas
Aggregations were particularly noticeable between April and June. Off Burleigh, recorded movements overlapped in small nearshore areas across several years. The repeatedly used core areas covered approximately 0.2 to 0.4 square kilometres. Rocky headlands, food and possible refuges could make these places attractive to young sharks.
The pattern at Noosa was less consistent: groups were repeatedly documented in 2023, but not during the corresponding period in 2024. This does not demonstrate that the animals had disappeared. Murky water or other observation conditions can prevent sharks that are present from being detected from the air.
Nursery areas remain unconfirmed
The footage demonstrates repeated use of particular stretches of beach by juveniles. However, it does not show whether individual sharks remain there for long periods or return regularly. Establishing this would require reliable identification and longer tracking of the same individuals. These data alone are also insufficient to confirm nursery status under the usual scientific criteria.
The authors suggest that older juveniles might use these more exposed coastal stretches after spending time in more sheltered juvenile habitats. However, a direct connection with neighbouring bays and estuaries has not yet been demonstrated. Acoustic tags could help test this possible habitat shift as the sharks develop.
What drones reveal — and what remains uncertain
The study primarily records readily visible animals during morning flights. It captures neither their full daily routine nor all the deeper areas they use. Occasional reactions to approaching snorkellers and paddleboarders were not measured systematically, so no quantified disturbance effect can be inferred.
Nevertheless, the footage provides an important conservation insight: even heavily visited beaches can be regularly used habitats for young sharks. Seasonal protection measures would therefore need to account for when the animals are present and how their habitat use overlaps with human activities. The study reveals these spatial patterns without yet explaining all their causes.
