How tracking technology is improving our understanding of at-sea threats to seabirds
Over the last three to four decades, industrial fisheries have expanded into far-flung oceans in search of lucrative fish such as bluefin tuna. Larger fishing areas and more fishing vessels have increased the likelihood of fatal interactions between boats, hooks and birds. It is estimated that around 100,000 albatrosses are killed each year by longline fisheries alone. Many breeding populations, such as those on Bird Island, South Georgia, have more than halved over this period.
Albatrosses can live for over sixty years. Spending 95% of their time at sea means their lives have been somewhat a mystery to us. Gaps in our understanding of where birds go when at sea have prevented accurate assessments of the threats posed by fisheries. Today, advances in remote tracking technology, such as GPS, make it possible for scientists to gather detailed information about their movements and feeding habits.
In a recent study, scientists from the British Antarctic Survey, RSPB, BirdLife International, CSIRO in Australia and Dalhousie University in Canada, combined information on seabird locations from the past 20 years with fishing activity to determine where and when birds are most at risk from fishing vessels.
A wandering albatross with a geolocator attached to its leg band. The device weighs less than 5g and records the bird’s position during its long migration around the Southern Ocean. © Richard Phillips
The data collected from miniature electronic tags (like the one in the picture above) were used to create monthly maps of seabird densities which were compared to maps of fishing activity to predict ‘hotspots’ of risk.
The results show that the birds are at highest risk during the southern hemisphere winter, and in the south Atlantic and southwest Indian Oceans. Moreover, the study helped determine that the pelagic longline fishing fleets of Japan and Taiwan, which target high-value tuna such as bluefin, represent by far the highest risk. Improved monitoring of these and other fleets is crucial for albatross numbers to recover.
“A suite of bycatch-reduction measures are available that can be extremely effective when used properly, for example in the toothfish fishery around South Georgia. However, South Georgia seabird populations continue to decline at alarming rates which indicates the failure of many fisheries elsewhere in the southern hemisphere to take full responsibility for impacts on seabirds and to become truly eco-friendly” explains co-author Professor Richard Phillips, Head of the Higher Predators and Conservation Group at British Antarctic Survey.
Maps showing annual predicted bycatch risk for four species of seabird from Bird Island, South Georgia (red = greatest risk).
Scientists hope this research will allow for greater regulation and accountability for fishing fleets. Having enough ship-based observers can be difficult for large fleets operating in the high seas, but electronic solutions exist, including tamper-proof video monitoring and satellite-surveillance to detect breaches. Fisheries managers must take action now to ensure bycatch mitigation is mandatory and that there is independent monitoring of compliance.
You can help by joining BirdLife International and other environmental organisations in calling for 100% observer coverage of tuna fleets. Sign here to help protect our seabirds: https://actionnetwork.org/petitions/unmonitored-unacceptable?source=direct_link #UnmonitoredUnacceptable
By Tommy Clay, seabird ecologist at University of Liverpool.
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