Gillnets are one of the most common types of fishing gear and are used extensively in most places where people fish for food. They operate by suspending a wall of netting in the water column.
Unfortunately, they are not selective in the species they catch. Sea turtles are one of the most common bycatch species that become entangled in these nets. When turtles are caught in gillnets, they can drown and die. Marine mammals, seabirds, and sharks are also frequently caught in gillnets.
Recently, researchers have been experimenting with illuminating the nets with LED lights to see if increasing net visibility reduces sea turtle bycatch.
Studies in Mexico show green sea turtle bycatch is reduced between 40-60% with no changes in target catch. Studies in Peru show green sea turtle bycatch is reduced between 65-80% with no changes in target catch. Studies in Indonesia show green olive ridley, and hawksbill sea turtle bycatch is reduced by 60% with increases in target catch and catch value.
Recent research shows that net illumination also reduces bycatch of other protected species such as seabirds, sharks and rays, as well as dolphins and porpoises.
The use of illuminated gillnets could prove beneficial to both sea turtles and fisherman by reducing the bycatch that can damage fishing gear.
Studies are now underway off the coast of North Carolina, where state gillnet fisheries are carefully managed to reduce turtle bycatch. Initial studies show that net illumination does not change target catch rates and may even decrease the bycatch of unwanted fish species. When it comes to protecting sea turtles, it looks like a good idea to keep the lights on.
Photo, posted June 2, 2016, courtesy of NOAA via Flickr.