Green light stops sea turtle deaths

14 Apr 2016

Conservation biologists have found that illuminating fishing nets is a cost-effective means of dramatically reducing the number of sea turtles getting caught and dying unnecessarily.

A team of researchers including Dr Jeffrey Mangel, a Darwin Initiative research fellow based in Peru and Professor Brendan Godley, from the Centre for Ecology and Conservation at the University of Exeter’s Penryn Campus, found that attaching green battery-powered light-emitting diodes (LEDs) to gillnets used by a small-scale fishery reduced the number of green turtle deaths by 64%, without reducing the intended catch of fish.

This innovative study was carried out in Sechura Bay in northern Peru and is the first time that lighting technology has been trialled in a working fishery. At a cost of £1.40 ($2) for each LED light, the research showed that the cost of saving one turtle was £24 ($34) - a sum which would be reduced if the method was rolled out at larger scale.

The researchers used 114 pairs of nets, each typically around 500m in length. In each pair, one was illuminated with light-emitting diodes (LEDs) placed every 10m along the gillnet floatline. The other net in the pair was the control and not illuminated. 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 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.

“This is very exciting because it is an example of something that can work in a small-scale fishery which for a number of reasons can be very difficult to work with. These lights are also one of very few options available for reducing turtle bycatch in nets,” said Dr Mangel.

Thousands of endangered turtles die as bycatch in gillnet fisheries around the world and it is hoped that this study will help to provide a solution. Professor Brendan Godley notes, “It is exciting to be part of research that is highlighting innovative methods that may assist the move towards sustainability in these fisheries. Understanding costings will help emphasise the need for institutional support from national ministries, international non-governmental organisations and the broader fisheries industry to make possible widespread implementation of net illumination as a sea turtle bycatch reduction strategy.”