The 2025 Sydney and Jervis Bay survey season was marked by some very pleasant and almost tropical conditions underwater. Throughout January, February and March, divers enjoyed water temperatures sitting in the mid-20s, with generally calm seas and moderate visibility, creating a welcoming backdrop for an intensive survey season.
In Sydney, our surveys began in late January and continued through to late June, spread over several months to accommodate the busy schedules of our dedicated volunteers. In contrast, our Jervis Bay trip was the complete opposite. It was a four-day marathon of diving and data entry in March, which was full-on from start to finish, but is always one of the most rewarding trips of the year.
Across both regions, the team completed an impressive 76 surveys of 29 sites, building on our long-term monitoring datasets and contributing valuable insights into the state of these temperate reef ecosystems. In total, 157 different species of fishes and invertebrates were recorded in Sydney and 198 species in Jervis Bay, highlighting the incredible biodiversity of these regions.
Some sightings stood out more than others. Divers were thrilled to encounter over 40 grey nurse sharks (Carcharias taurus) at Bowen Island in Jervis Bay, as well as a lone individual at The Gap in Sydney. Adding to the excitement, the hermit crabs Calcinus minutus and Paguristes pugil were recorded for the first time in Sydney waters, extending their known range.
Not all findings were as welcome, however. In Jervis Bay, divers noted the increasing spread of mussels forming large beds in the shallow reefs. These beds are raising concern among researchers and managers, and there is ongoing discussion about potential escapees from mussel farms becoming established within the Marine Park, potentially presenting new ecological challenges for the region’s native reef residents.
These surveys not only contribute to our understanding of local reef health but also feed into the broader RLS global database, helping to track changes in marine ecosystems over time. From exciting new records to pressing management concerns, the 2025 Sydney and Jervis Bay surveys remind us just how dynamic, diverse, and often vulnerable our temperate reefs can be.
Now, in May 2026, our next round of Sydney surveys are ongoing, and Jervis Bay surveys have recently wrapped up with 57 transects surveyed across 14 sites by our team of 11 volunteers.
None of this work would have been possible, nor anywhere near as enjoyable, without the commitment and teamwork of our incredible volunteers. A huge thank you goes out to Josh B and Josh M, Ann, Kris, Hatty, Nyrie, Ari, Troy, Nathan, Norm, Bruce, Eve, Lexi, Lara, Dave, and Naomi for their tireless efforts in collecting high-quality data and for being such great dive buddies no matter the conditions thrown our way. Special thanks also to Norm, Bruce, Nathan, and the Underwater Research Group of NSW, whose boats and logistical support made these surveys possible. Additional thanks to Bruce and Sue for tank filling support!
