Green Light For Turtle Friendly Fishing Nets?Reading time: 2 minutes
New research has shown that attaching green battery-powered light-emitting diodes (LED) to gillnets used by a small-scale fishery can help to reduce the number of green turtle deaths by 64 percent.
Conservation biologists Dr Jeffrey Mangel and Professor Brendan Godley from the University of Exeter have been part of a team of researchers involved in an innovative study aiming to reduce the number of unnecessary turtle deaths in small-scale fisheries. The study, carried out in Sechura Bay in northern Peru, was the first of it kind to trial lighting technology in a working fishery. The Peruvian coastal waters are used as foraging grounds by a host of sea turtle species including green, olive ridley, hawksbill, loggerhead and leatherback turtles.
A major threat to these sea turtle populations is Peru’s gillnet fleet which comprises the largest component of the nation’s small-scale fleet. It is estimated to set at least 100,000 km of net per year leading to the death of thousands of sea turtles as a result of being caught as non-target species (known as bycatch). This ongoing trend means the turtle populations of the eastern Pacific region are now seen as some of the world’s most vulnerable to fishing pressures.
Illustration of a bottom set gillnet anchored to the seafloor. Image credit: Michigan Sea Grant
The study involved 114 pairs of nets each around 500-metres in length. For each pair, one was illuminated with light-emitting diodes (LEDs) placed every ten metres along the gillnet floatline and the other was not illuminated (to be used as a control). The control nets caught 125 green turtles while illuminated nets caught 62. The target catch of guitarfish was unaffected by the net illumination. Each LED light cost £1.40 ($2) meaning the cost of saving one turtle was £24 ($34); a sum which would hopefully see a major reduction if this method was to be scaled up. The researchers are now working with larger fisheries in Peru and with different coloured lights to see if the results can be repeated and applied with more critically endangered species.
Green turtles (Chelonia mydas) entangled in a small-scale gill net. Image credit: Bryan Wallace
Bycatch is a global issue which threatens the sustainability and resilience of our fisheries and ecosystems. It is hoped that funding research like this can help reduce global bycatch significantly and contribute to the currently inadequate mitigation methods.
Link to full ScienceDaily article here
Link to a poster summarising the project here
Link to journal article here – “Green light stops sea turtle deaths: Illuminating fishing nets is a cost-effective means of dramatically reducing the number of sea turtles getting caught and dying unnecessarily” (Ortiz et al., 2016)
Featured image credit: University of Exeter