New research has raised hopes of reducing the tragic incidental impacts of commercial fishing on large seabirds between Australia and South America.
The University of the Sunshine Coast-led study into the endangered Antipodean albatross pinpoints where and when these seabirds are most at risk of injury or death from fishing longlines across the South Pacific Ocean.
“A major cause of rapid population decline for migratory albatrosses and petrels is fisheries bycatch, which occurs when the birds are caught or entangled on pelagic longlines with thousands of baited hooks,” said UniSC Associate Professor Kylie Scales.
“It’s of great concern that many of the interaction hotspots we identified between birds and fishing vessels are located on the high seas and therefore not under any individual country’s jurisdiction."
“However, we’re excited at the promise of this data-driven method for identifying and predicting hotspots of fisheries interaction risk. We hope it will prompt tighter controls in key fisheries to mitigate the threats to wildlife and make the industry more sustainable.”
Ho Fung (Billy) Wong, lead author of the collaborative research paper published in Biological Conservation, said the Antipodean albatross was chosen as a case study because of imminent fears for its future.
“These birds only breed every two years on small New Zealand islands and are already threatened by the effects of climate change and marine plastics,” said the UniSC PhD researcher.
“Their long wingspan means they can fly thousands of kilometres, cruising above the ocean surface, diving in search of fish and squid, and we wanted to explore the factors leading to interactions with fisheries.”
Fieldwork was carried out by researchers at the New Zealand Department of Conservation at the main breeding colony on Antipodes Island, where satellite tracking devices were attached to the backs of 192 albatrosses of various ages and sexes.
The birds’ movements were monitored between 2019 and 2022 as they ranged between southern Australia and South America.
Results were combined with data on the footprint of commercial fishing activity, together with real-time mapping of ocean features not previously taken into account.
These features included thermal fronts (the meeting of two water masses) and eddies (large swirling currents on the ocean surface).
Dr Scales, a marine ecologist who co-authored the paper with UniSC’s Professor David Schoeman, said the resulting map of overlapping areas represented bird danger zones.
“We found the most intense risk zones occur in our winter, among juvenile and female albatrosses, in a latitudinal band near the Tropic of Capricorn from 25 to 40 degrees south of the Equator,” she said.
“This new information on the spatial structuring of risk zones is important for the survival not only of this population, but the thousands of seabirds caught as bycatch every year. We’re now working to expand the research across the world.”
The study was a collaboration with the New Zealand Department of Conservation, Plymouth Marine Laboratory (PML) in the United Kingdom, The University of Queensland, Charles Sturt University, Halpin Wildlife Research in Canada, and South Africa’s Nelson Mandela University.
PML’s expertise in Earth observation was used to examine how physical ocean features shaped the danger zones.
“We analysed the information at two scales: seasonal patterns using long-term climate data, and finer monthly patterns using real-time ocean conditions,” said PML Marine Earth Observation Scientist Dr Peter Miller.
“The danger was shown to be particularly acute during the Southern Hemisphere winter months and with younger birds facing the highest risk of all.”
Mr Wong said the findings led the team to recommend that seabird bycatch mitigation measures set by Regional Fisheries Management Organisations (RFMOs) such as the Western and Central Pacific Fisheries Commission should be extended to cover risk zones identified in the study, especially 25-30 degrees south.
“Currently, only one of three mitigation measures is mandated in this zone,” he said.
Mitigation measures include bird-scaring lines, branch-line weighting and night-setting.
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