A seabird success story for conservation
Tori lines have become part of everyday life at sea and fishermen no longer resist their use.
23 February 2021 | Supplements
The effort to reduce seabird mortality is documented in the paper “Reduction in seabird mortality in Namibian fisheries following the introduction of bycatch regulation” published in ScienceDirect.
The Namibian hake demersal trawl and longline fisheries have been required to use bird-scaring lines since 2015. This was after it was estimated that up to 30 000 birds were killed each year.
A trawler’s bird scaring line, or tori line, consists of about 30m of strong rope, with 5-10 paired streamer lines of lighter, visible material, attached at 2m 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.
What was concerning was that birds getting killed included threatened species like the endangered Atlantic Yellow-nosed Albatross (Thalassarche chlororhynchos) and the vulnerable White-chinned Petrel (Procellaria aequinoctialis).
These impressive oceanic wanderers (with wingspans of up 3.5m) can effortlessly travel the world’s oceans, sometimes covering up to 2 000km in a day. This brings them into contact with many different fishing fleets from different nations.
According to the paper’s Abstract, data from BirdLife International’s Albatross Task Force and the Namibian Fisheries Observer Agency was used to quantify changes in seabird mortality in these fisheries before and after the introduction of these regulations.
“Our estimated bycatch rates in the longline fleet were 0.468 birds/1 000 hooks before regulations, and 0.004 birds/1 000 hooks following their introduction, which is a 98.4% reduction,” the researchers reported.
“Our estimate suggests that 215 (1-751) seabirds were killed across this fleet in 2018 compared to 22 222 (3 187-68 786) in 2009.”
Titus Shaanika, Senior Albatross Task Force (ATF) instructor in Namibia, says the big challenge is to maintain the reduction rate “and to wear them as a badge of honour”.
“We can and we must do more of this across the world if we want turn the tide on biodiversity loss,” he says.
Namibia’s hake fishery is a recipient of MSC certification with bird bycatch being an important consideration in the assessment. Conditions of certification include having to improve compliance with bird-scaring line use in the trawl fleet, and to ensure that robust data collection on bycatch continues.
The Namibian team is the second of five ATF teams across the world to have achieved a more than 90% seabird bycatch reduction. South Africa achieved more than 90% seabird bycatch in the country’s hake trawl fishery in 2014. Like Namibia, it also took South African fishermen about 10 years to reach acceptance of these preventative measures.
In the next two years the aim of the BirdLife International Marine Programme is to demonstrate similar reductions in Argentina and Chile.
The use of tori lines is endorsed by the Responsible Fisheries Alliance (RFA), a group of like-minded organisations that promote responsible fishing practices amongst other things.
Source: Fishing Industry News Southern Africa