The Australian Antarctic Program, coordinated by the Australian Antarctic Division (AAD), organised two voyages on the RSV Nuyina to Heard Island and McDonald Islands (HIMI) in summer 2025/26. The aim for the HIMI Management Campaign was to undertake the first dedicated environmental management visit to the territory in more than 20 years. As part of the second Voyage, benthic and fish surveys were planned to assess benthic habitats and improve the understanding of demersal and pelagic fish biodiversity and productivity in the Marine Reserve around HIMI. These surveys were designed to complement an annual random stratified trawl survey that has been conducted annually around HIMI since 1997.
The surveys were plagued by a range of operational difficulties and harsh environmental conditions. For the benthic survey, a total of 7 benthic camera tows and 6 beam trawls were deployed in depths ranging from 100-850m, while for the fish survey only two otter demersal trawls and one midwater trawl could be completed. While the overall sampling activities were disappointing and unlikely to be sufficient to allow quantification of fish biodiversity and productivity in water close to Heard Island, the team gained valuable operational experience for future marine science voyages. Photographs of many fish specimens were taken which will improve the species range and quality of photos for the Southern Ocean fish guides available for fisheries observers. Specimens were also retained for the Australian Fish Collection. Successful zooplankton trawls and wet well plankton tows provided new data to quantify the surface zooplankton production around Heard Island and captured a range of larval fish. In addition, proof of concept was obtained for retaining and potentially returning live fish in containerised aquariums to the new Southern Ocean Aquarium in Tasmania.