Ranger led marine ecological surveys within the Joseph Bonaparte Gulf Marine Park

The Joseph Bonaparte Gulf Marine Park (JBGMP) is located across the Northern Territory and Western Australian border. The remote nature of the park has limited what information we have of the marine environment, fauna and flora within this region. The Thamarrurr Traditional Owners and by extension the Thamarrur Rangers, based in the township of Wadeye are key custodians for the land and sea country for this region. This project delivered a training program to the Thamarrurr Rangers to enable them to conduct marine monitoring within and adjacent to the JBGMP and collect baseline information on the fish fauna and benthic habitats within a section of the Marine Park. This report presents the results of the two-year project that outlines the training conducted by the Australian Institute of Marine Science (AIMS), and the baseline data collected by AIMS and the Thamarrurr Rangers on the marine biodiversity at multiple locations within the JBGMP. The Rangers conducted fish biodiversity surveys using Baited Remote Underwater Video surveys (BRUVs) and collected information on the benthic seabed community using drop camera surveys (DropCam). Sites selected for these surveys were identified through previous participatory mapping work conducted with Traditional Owners and Rangers from the Wadeye community, and included Emu Reefs, Emu Break and Howland Shoals within the JBGMP, and an additional coastal site, Tchinbilli Reef, adjacent to the Marine Park.
A total of 59 BRUVs deployments and 26 DropCam transects were conducted over four one-week trips between October 2020 and July 2022. The BRUVs surveys identified 79 species across the four locations, including 10 threatened and endangered species of elasmobranchs (sharks and rays). High turbidity conditions at Tchinbilli Reef limited the amount of information on fish fauna at the coastal location, however still provided some baseline information on the fish biodiversity in coastal regions adjacent to the JBGMP. Spatial patterns of deployments within the Marine Park suggested locations on the central and southern Emu Reefs were key hotspots for marine biodiversity, with all locations recording healthy populations of key species identified as important to the Traditional Owners (i.e., Emperors, Snappers, Rockcods, Trout &amp; Mackerel). Habitat information extracted from BRUVs videos were also used to assess species-habitat associations across the region, highlighting the increased biodiversity value of hard substrate (e.g., patch reefs, bedrock and rocky reefs) within the JBGMP, that is more broadly dominated by soft substrate habitats. DropCam surveys provided novel information on the spatial distribution of habitat types across Emu Reefs, again identifying key patch reefs and sandflat habitats around the southern and central Emu Reefs.
The collection of baseline information on the fish composition, distribution and benthic habitat associations now enables the development of a continued monitoring to evaluate the health of the sea country over multiple years. The successful training of the Thamarrurr Rangers in marine monitoring techniques can now enable the Ranger group to carry out yearly monitoring trips at Emu Reefs. This report uses the findings from the baseline information and learnings from working with the Rangers to provide guidance to develop a further program with the Thamarrurr Rangers to monitor the health of the sea country within and adjacent to the JBGMP.

Organization: Australian Ocean Data Network