Endangered loggerhead turtles snared by longline fishermen may be inadvertently lured to the hooks because of an attraction to light sticks designed to attract tuna and swordfish, researchers said.
Scientists at the University of North Carolina at Chapel Hill found in lab experiments that young loggerhead turtles will swim toward lights similar to those used by fishermen to attract big fish.
"Juvenile turtles are indiscriminate eaters and bite nearly everything small that they encounter," said Ken Lohmann, a UNC biology professor whose expertise is turtle navigation.
Lohmann recommended that longline fishermen direct the lights, designed to mimic the nighttime luminescence of squid, toward the bottom of the ocean. Turtles spend most of their time near the surface.
"The fish are found at much greater depths," Lohmann said. "If the lights are shaded so that the lights are directed downward, the turtles may not see them."
He also suggested that fishermen switch to colors of light that turtles can't detect.
Lohmann conducted the study with John Wang, a graduate who is now a research associate at the University of Hawaii and National Marine Fisheries.
Inadvertent turtle catches have long been a concern, said David Bernhart, chief of protected resources for National Marine Fisheries in the Southeast region.
U.S. longline fishermen working in the Atlantic have had to use circle hooks since 2004 to limit inadvertent catches, a change Bernhart said reduced the number of turtles captured by 50 percent.