Little green lights could save sharks and turtles while keeping fisheries in business.

Science magazine reports on one of those simple fixes that could make everything a little bit better if only everyone would sign on. Scientists have found that by attaching green LEDs to fishing nets, we could reduce “bycatch” (that is, trapping the wrong kinds of sea creatures in fishing nets) without cutting back on the number of the fish we *do* want to catch:

National Oceanic and Atmospheric Administration marine ecologist John Wang and his colleagues previously devised illuminated nets to address turtle bycatch. Turtles are particularly good at seeing green light, and when the researchers found in 2016 that the lit nets cut back on turtle bycatch by 64%, they thought other marine animals might see the same benefit.

The team partnered with small-scale grouper and halibut fishers in the waters off the coast of Baja California in Mexico because of the plentiful turtles and other large marine animals there, says Jesse Senko, a conservation ecologist at Arizona State University, Tempe, and lead author of the new paper. The researchers deployed 28 pairs of nets; one net in each pair was affixed with LED lights in 10-meter increments. Then, the researchers weighed and identified each critter that was snared overnight.

The lit nets brought in 63% less bycatch, including 51% fewer turtles and 81% fewer squid, than the dark nets, the researchers report today in Current Biology. The most “gratifying” result, Lewison says, was with elasmobranchs, the group that includes sharks and rays. In the Gulf of California, she says, shark bycatch is “a huge issue.” In the new study, it went down by a whopping 95%.

Researchers are still investigating why some animals seem to avoid the lights better than others. Elasmobranchs have sophisticated eyesight, and Humboldt squids have large eyeballs, so those animals might easily spot the green radiance, the researchers say. But it’s probably too simple to say the target fish simply can’t see the lights as well as the other animals do, Wang says.

Meanwhile, just as many of the target fish were caught as before, but fishers spent only half the time hauling in and disentangling the nets. The major drawback, Senko says, is that it costs up to $140 to equip a net with lights, which is more than some fishers can afford.

You can read more of the NOAA research here, in Current Biology.