Novel deep sea camera systems have shown that Australian commercial fisheries are having little impact on seafloor biodiversity around Heard Island and McDonald Islands (HIMI).
In combination with scientific sampling, the cameras revealed that more than 98% of sensitive seafloor biodiversity in the HIMI fishery remain in pristine condition following commercial fishing over the past 16 years.
The eight-year study, funded by the Fisheries Research and Development Corporation, was a joint project between the Australian Antarctic Division, the Australian Fisheries Management Authority and fishing industry partners, Austral Fisheries and Australian Longline.
Australian Antarctic Division fisheries scientist, Dr Dirk Welsford, said the project aimed to investigate the potential impacts and sustainability of trawling and longlining for Patagonian toothfish in the Australian Fishing Zone at HIMI, and to develop technologies that could be used by other fisheries to address similar issues.
A key part of the project was the development of underwater still and video camera systems, which attached to trawling and longlining (‘demersal’) fishing gear to observe the impact of the gear on seafloor habitat.
‘The cameras were designed for easy use by the fishing industry,’ Dr Welsford said.
‘They are robust, automated systems that can be deployed on fishing gear to allow fishing vessels to see whether the habitat they are working in contains sensitive seafloor species, and what happens when fishing gear disturbs organisms on the seafloor.’
This video footage, along with scientific sampling of seafloor communities, was used to assess the risk of demersal fishing to those communities and to identify strategies to minimise fishing impacts, such as gear modification or the avoidance of sensitive areas.
‘Our study showed that the majority of vulnerable organisms live on the seafloor at depths less than 1200m,’ Dr Welsford said.
‘This range overlaps with the depths targeted by the trawl fishery and to a lesser extent by the longline fishery. However, as the majority of trawling has focussed on a few relatively small fishing grounds, less than 1.5% of the biodiversity in waters less than 1200m are estimated to have been damaged or destroyed.’
The study estimated that 0.7% of the sea floor within the HIMI fishing zone has had some interaction with fishing gear since the fishery’s inception in 1997. It also estimated that the HIMI Marine Reserve, where fishing is not permitted, contains over 40% of the seafloor organisms considered vulnerable to demersal fishing at HIMI.
‘A key element of the management strategy for mitigating the impact of demersal fishing is the extensive marine reserves established around HIMI and Macquarie Island,’ Dr Welsford said.
‘This work has directly led to the expansion in March this year of the HIMI Marine Reserve by 6200km2, to protect a range of distinct seafloor habitats and vulnerable species of conservation significance. The HIMI Marine Reserve now covers over 71 000 km2.’
The report concluded that the risk that fishing will cause significant impacts to seafloor biodiversity at HIMI is likely to be low over the medium term. It recommended that risk assessments for the fishery be updated regularly, to evaluate the likely performance of the current management approach in the long term.
The results of the study will help inform discussions with the Commission for the Conservation of Antarctic Marine Living Resources, which manages fishing activities in the Southern Ocean, as well as international conversations on demersal fishing impacts.
Corporate Communications, Australian Antarctic Division