Fishing nets kill thousands of sea turtles every year, and each death is a hard blow: Most of the species are endangered.
A new study from the University of Exeter, however, is floating a simple solution that might help save countless numbers of the shelled reptiles.
Scientists added green, low-power LED lights to the types of fishing nets that pose the biggest risk to sea turtle populations.
"[W]e are hoping that ... reducing bycatch, particularly in gillnets, will help with the management and eventual recovery of these populations," said lead researcher Jeffrey Mangel in a statement.
Scientists and conservation organizations like the World Wildlife Fund use the word "bycatch" to describe animals caught unintentionally through various fishing methods.
Gillnets like the one below are designed to catch target fish by letting their heads through, but not the rest of their bodies. Unfortunately, the same thing happens to sea turtles.
When turtles get tangled in the nets, they can drown. Even if they manage to free themselves and make it to the surface, they may be fatally injured — the nylon strings can cut into the soft tissue around their neck and fins.
The lights are also inexpensive. At only $2 per unit, the researchers estimate that it only costs $34 to save one turtle. They note that large-scale production and implementation could drive the cost down even further.
Using 114 pairs of gillnets off the coast of Peru, scientists placed the LEDs every 32 feet along a 547-yard net. They found that nets without the lights caught 125 turtles, while the illuminated nets only caught 64.
"The idea of using lights comes from asking how we can change the behavior of animals," Mangel wrote in an email to Tech Insider. The idea is similar to acoustic warnings, or "pingers," that researchers have found effective in deterring dolphins and porpoises from fishing nets.
While Mangel said it was challenging to nail down exactly what it is about the lights warns the turtles away from the nets, he speculated that the light may make the nets more visible, making them easier for the turtles to avoid.
An added benefit is that guitarfish, the species the fisheries are actually targeting, can't see the green light — it's outside the spectrum of color the fish can see.
Wide-scale adoption by fisherman could go a long way. In 2013, marine biologist Bryan Wallace wrote in the Huffington Post that there are an estimated 62,000 miles of gillnets in the waters off the Peruvian coast.
Next, Mangel said, the team is now experimenting with different colored lights that might warn away other endangered species while preserving catch quantities for the fishermen. He's particularly interested in working with fisheries that commonly (and unintentionally) catch seabirds and smaller dolphins, porpoises, and whales.
Given that scientists estimate we lose at least several thousand species each year, solutions like these — innovative, cheap, and effective — are a bright spot in the battle to stave off rapidly disappearing biodiversity.