The Reef Bommie Modules were strategically placed at three easily accessible fishing platforms in the lower Pioneer River estuary, in the heart of Mackay City. The Reef Bommies aim to provide hard vertical relief fish habitat and enhance recreational fishing opportunities for locals, tourists, and visitors to the region. The Reef Bommies were designed by Catchment Solutions, and certified by structural and coastal engineers for integrity and stability within the marine environment. Central to the design of the Reef Bommie Modules was the incorporation of improved settlement surfaces on the outside of the modules to assist recruitment of marine sessile organisms such as bivalves (oysters) and corals. Surface roughness was combined with underhangs and structural complexity to provide ideal conditions for reef building fauna to colonise the Bommies and create functioning reef ecosystems. A cave has been incorporated at the bottom of the modules to provide habitat for iconic large-bodied fish species such as mangrove jack and barramundi, while a separate internal chamber located towards the top of the module and accessible only via small 100 mm openings has been included to provide refuge areas for juvenile and small-bodied fish species.
In October 2022, 18 months after deployment, Catchment Solutions conducted post-deployment monitoring using Baited and Un-baited remote underwater video stations (BRUVS). This monitoring aimed to assess fish utilisation, species diversity, abundance, overall module condition, and validate the methodology for future projects.
Monitoring results demonstrated that Reef Bommie Modules are providing fantastic habitat for a wide range of iconic fish species, with 22 species identified, an increase of 19 species when compared to pre-deployment surveys. Fish species included large barramundi, mangrove jack, golden snapper, estuary cod, barred grunter, giant trevally, barracuda, sand bass, yellowfin, and pikey bream. Herbivorous fish species were also recorded utilising the modules including rabbitfish, red scats and wrasse species. These ecosystem engineers play a vital role in the health of marine environments by grazing on macro-algae that deprives corals of light and oxygen. Many juvenile fish species were also recorded using the modules as nursery habitats, including estuary cod, golden snapper and brown sweetlip. Baited and Un-baited surveys provided different insights, with Baited surveys proving more effective in attracting fish closer to the camera and assisting with identification.
The chosen sampling methods allowed for non-lethal and non-intrusive data collection, while also providing footage for calculating relative abundance, species richness, and community outreach purposes. However, it’s important to note that these methods may yield conservative figures due to counting only the maximum number of a given species in one frame to eliminate bias.
Experience the astounding results for yourself in the video below!
The fishing platforms have been widely utilised by the local community, with recreational fishers reporting great success catching sought-after species such as barramundi, golden snapper, barred grunter, estuary cod, and yellowfin bream. A local school near the Bridge Road fishing platform has even incorporated a fishing program into its curriculum, taking advantage of the fishing platform and the enjoyable fishing experience it provides. This demonstrates the community’s appreciation for easily accessible fishing platforms and the effectiveness of the habitat structures.
The results from pre and post-monitoring fish surveys confirms the resounding success of the project. Both the fishing platforms and fish habitat structures have exceeded expectations, with a significant number of fish utilising the Bommie habitat and positive feedback from the local community. The project has successfully attracted iconic recreational fish species, including herbivorous ecosystem engineer species, and provided refuge habitats for juvenile fish. It’s anticipated that the footage and results obtained will encourage more community members to utilise the fishing platforms and inspire other councils and organisations to enhance estuarine ecosystems and fishing opportunities for their communities.