Scientists are praying green light could offer marine animal conservationists a glimmer of hope.
A new study found that green LED lights affixed to gillnets—a type of net that hangs like a curtain in the water—reduced the number of cormorants, a type of sea bird, unintentionally snared when diving into the water for fish by 85 percent. Previously without the light as a deterrent, birds would dive into nets mistaking them for prey and end up severely injured or dead.
The green light method was originally developed to save sea turtles. Green became the color of choice because turtles can see the wavelength, but fish cannot, meaning the light can be used to deter turtles away without jeopardizing catch.
All sea turtle species are either threatened or endangered, and accidental catch by fishermen poses a threat to their existence. Previous studies by the same research group showed that the number of sea turtles accidentally caught in fishing nets dropped by 64 percent when green LEDs were in place. The new study published in the journal Open Science is giving researchers hope that more species can be saved with a low-cost tool.
Sea creatures that get dredged up onto fishing boats unintentionally are referred to as bycatch. It's an unintended consequence both fishers and conservationists try to avoid. Everything from dolphins and whales to turtles and sharks end up as bycatch every year. For species whose population numbers are already low, bycatch only worsens their dilemma.
Fishers try to find the best ways to avoid bycatch because anything the ends up caught in the net that wasn’t supposed to may cause damage to fisher’s nets.
In the case of a gillnet, a turtle or bird might simply be able to evade capture because it sees a barrier in the water.
In Peru, gillnets are the most common fishing method used by small-scale fishing operations, and our hopes are that integrating lights into fishing techniques will help find a happy middle ground between those who live off the fish in the water, and those who want marine animals to keep living.