CAPE TOWN – Accidental seabird deaths during fishing is the single greatest threat facing many seabird populations. Albatrosses, in particular, are under extreme pressure with 15 of the world’s 22 albatross species threatened with extinction.
This month BirdLife South Africa staff and collaborators have published a 7-year study, showing that the hake trawl fishery in South Africa has reduced albatross deaths by 99%.
In recent years, deep-sea trawl fisheries have been identified as a major cause of accidental seabird deaths. Trawlers use large nets, held in the water by thick cables, to capture fish living on the sea floor. Seabirds, especially albatrosses and petrels, are attracted in their thousands to the trawlers when fish offal (unwanted heads and guts) is discarded from the onboard processing factory. While scavenging, seabirds are vulnerable to becoming entangled with the cables, and being dragged underwater and drowning.
In 2004 the hake trawl fishery became the first fishery in Africa to obtain Marine Stewardship Certification (MSC). MSC certification ensures that fished stocks remain stable and healthy, that ecosystem-wide impacts are minimised and not significant, and that there is continued monitoring and compliance to prescribed fishing regulations.
As a condition of certification, the fishery had to assess the risk of seabird bycatch. They discovered that each year around 10 000 seabirds (70% of which were albatrosses) were being killed accidentally.
BirdLife South Africa recommended the use of a single measure – called a bird scaring line, to address this problem, and in collaboration with fishing companies they got onboard and conducted scientific research into the effectiveness of the measure. Now their data, collected over five years, has been published in the international, scientific journal Animal Conservation, and shows a 90% reduction in seabird deaths and 99% reduction in albatross deaths since 2006.
A trawler’s bird scaring line consists of about 30 m of strong rope, with 5-10 paired streamer lines of lighter, visible material, attached at 2-m intervals. The main line is tied to the back of the moving trawler, with a road cone at the seaward end providing drag that tensions the line and keeps it aloft behind the vessel, usually parallel with the trawl cables. The paired streamer lines hang downwards from the mainline and distract and confuse birds enough to keep them away from the trawlers’ cables.
The lines are built through a collaborative project between BirdLife South Africa and the Ocean View Association for Persons with Disabilities (OVAPD) with sponsorship from Total South Africa. A team of ten individuals with various intellectual and physical disabilities from OVAPD can build a line in under an hour. These lines are then sold to the fishing industry to bring in a small income for the OVAPD centre.
“We’ve worked closely with this fishery since the early 2000s to demonstrate that avoiding seabird bycatch is good for business and for the environment. Moreover it’s relatively easy given the right tools.” said Bronwyn Maree, Albatross Task Force Leader for BirdLife South Africa.
“Bird scaring lines have now become part of everyday life at sea and fishermen no longer resist their use,” she continued.
The research will be available from 30 April at http://doi.wiley.com/10.1111/acv.12126. The full citation is:
Maree, BA, Wanless RM, Fairweather TP, Sullivan BJ & Yates O. 2014. Significant reductions in mortality of threatened seabirds in a South African trawl fishery. Animal Conservation 17: published online
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