By Binzy Reynolds:
Illuminating fishing nets can reduce the terrible impact they have on the lives of seabirds and marine-dwellers by over 85 per cent, new research shows. An international team of researchers, led by Dr Jeffrey Mangel from the University of Exeter, proved the number of birds caught in gillnets can be drastically reduced by attaching green battery-powered light-emitting diodes (LEDs).
Peru’s gillnet fleet is conservatively estimated to set 100,000km of net per year, in which thousands of turtles and seabirds die unintentionally as “bycatch.”
This innovative study was carried out in Sechura Bay in northern Peru. Researchers used 114 pairs of nets, each typically around 500-metres in length. In each pair, one was illuminated with light-emitting diodes (LEDs) placed every ten metres along the gill net floatline. The other net in the pair is the control and was not illuminated. The nets are anchored to the seabed then left in situ from late afternoon until dawn, when the fishermen collect their haul. The control nets caught 39 cormorants, while the illuminated nets caught just six. A previous study, using the same LED technology, showed they also reduced the number of sea turtles also caught in gill nets. Multiple populations of sea turtle species use Peruvian coastal waters as foraging grounds including green, olive ridley, hawksbill, loggerhead and leatherback.
For that study, the researchers found that the control nets caught 125 green turtles while illuminated nets caught 62. The target catch of guitarfish was unaffected by the net illumination. The researchers believe LEDs offer a cheap, reliable and durable way to dramatically reduce the capture and death of birds and turtles, without reducing the intended catch of fish. They are now working with larger fisheries in Peru and with different coloured lights to see if the results can be repeated and applied to more critically endangered species.
The findings have been published in the Royal Society journal Open Science on Wednesday, July 11 2018.
Lead author Dr Mangel, from the Centre for Ecology and Conservation at the University’s Penryn Campus, said: “We are very encouraged by the results from this study. It shows us that we may be able to find cost-effective ways to reduce bycatch of multiple taxa of protected species and do so while still allowing fishers to earn a livelihood.”
Professor Brendan Godley, who is an author of the study and Marine Strategy Lead for the University of Exeter, said: “It is satisfying to see the work coming from our Exeter Marine PhDs leading to such positive impact in the world. We need to find ways for coastal peoples to fish with the least impact on the rest of the biodiversity in their seas.”