Shining a light on bycatch: ASU-led study points to global solution

Kayla Burgher spends her summers on a small fishing boat off the coast of North Carolina, hauling massive nets onto the deck and fastening green LED lights along their edges.

The lights serve a simple but powerful purpose: They warn endangered sea turtles away from the nets, reducing the risk that the animals will be accidentally caught and killed as bycatch. Burgher, a PhD candidate in Arizona State University’s School of Life Sciences, and researchers in the Senko Lab have shown that this illuminated-net strategy can dramatically reduce sea turtle deaths.

Now, new research suggests the benefits extend far beyond turtles. In a study published last week in Biological Conservation, Burgher analyzed seven years of data and found that illuminated nets also significantly reduce bycatch of a wide range of species — from hammerhead sharks to stingrays — off the coast of Mexico.

“Most papers have looked at sea turtles,” Burgher explains, “But there has been no comprehensive analysis of either fish, sharks or rays, so this study was unique in that way.”

Burgher found that the presence of lights on the fishing nets consistently reduced the amount of accidentally caught elasmobranchs — or sharks, skates, and rays — proving that net illumination is a promising marine conservation tool for many endangered species.

But her study went further than that: She also analyzed what kinds of lights worked best for different species. The study included data from tests with four different kinds of lights, including the green LEDs most commonly used to save sea turtles, as well as orange LEDs, UV LEDs and green glow sticks. With that data, Burgher was able to analyze how over 40 marine species reacted to the different kinds of light.

“We found that elasmobranchs had consistent reductions across all four light types, but the orange light worked best, with around a 50% reduction,” she shares. “And most of the elasmobranch species that we found reductions in are classified as vulnerable or even more endangered by the IUCN.”

But there's the worry that adding lights to fishing nets would also deter the fish that the fishermen actually want to catch — like halibut, yellowtail, or flatfish. That’s why Burgher also looked at how the lights affect the fish that people like to eat.

“We basically found no reductions for bony fish,” Burgher explained.

So net illumination seems to be a win-win for everyone: It allows fishermen to keep their businesses running without doing nearly as much damage to the endangered species conservationists want to protect.

And even though the data Burgher used was collected off the coast of Mexico, her results are useful for fishermen around the world.

“We included so many species that are found across the world’s oceans. So this is applicable globally,” she says.

Burgher’s analysis provides concrete recommendations that fishermen can pick and choose from according to what species live in their area. For example, while a fisherman off the coast of North Carolina might use green LEDs to protect sea turtles, a fisherman in the Caribbean might use orange lights to protect manta rays. 

Together, the findings show that a simple strand of lights can offer a solution to one of fisheries’ most persistent challenges. By tailoring net illumination to the species in their waters, fishermen around the world can significantly reduce harm to vulnerable sharks, rays and sea turtles — without sacrificing their catch.

For Burgher, the work transforms long days on the water into something bigger: a practical, globally applicable tool that proves conservation and commerce don’t have to be at odds — they can move forward together.