A simple trick can save thousands of sea turtles

Sea turtles often fall prey to a commonly used device that is not meant for them: fishing nets. Scores of the placid reptiles perish after getting entangled in nets by drowning or starving or suffering incapacitating injuries.

But it does not have to be that way, says a team of British scientists.

Conservation biologists at the University of Exeter recently came up with a simple solution: attaching green battery-powered LED lights to gillnets used in small-scale fishing. The biologists found that this simple trick reduced the number of deaths among endangered green sea turtles by 64% without affecting fishermen’s intended catches in any way.

Better yet: the LED lights can be had for a pittance with each of them costing the equivalent of around $2. In other words, saving green turtles by help of the net illumination method would be highly cost-effective. International NGOs and conservationist groups might be willing to underwrite costs for local fishermen in an effort to save endangered turtles.

“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. Jeffrey Mangel, one of the researchers involved in the study.

Gillnets, which are generally made of monofilament or multifilament nylon, are attached to fixed poles and strung across sea floors like tennis nets, thereby acting as buoyant undersea walls of mesh at various depths. Unintentionally, however, they also entangle animals like turtles and porpoises. Thousands of endangered turtles perish each year globally as so-called bycatch in gillnet fishing.

To test their invention, the scientists placed the LEDs every 10 meters along a 500 meter wall of 114 pairs of gillnets off the coast of Peru. Nets without lights caught 125 turtles, whereas those illuminated by lights ensnared only 64. That is because the lights tend to deter turtles which shy away from them.

In effect, the LED lights function the same way as acoustic warnings, or “pingers,” that are already in use worldwide to keep dolphins away from fishing nets.