Gillnets are one of the most widely used fishing gear in coastal areas of the world's oceans, but they also often catch other animals that fishermen do not target. These include endangered, threatened and protected species such as sharks, sea turtles, marine mammals and seabirds, but also other species and non-marketed juvenile target species. These animals are often dead, wounded, and thrown overboard.
The incidental catch of non-target species in coastal gillnet fisheries – known as "bycatch" – has led to the decline of endangered species worldwide, while also affecting coastal ecosystems.
Over the past decade, the illumination of gillnets with LED lights has become an effective tool for reducing bycatch of endangered sea turtles in coastal gillnet fisheries. However, the effects of net lighting on other vulnerable species, total fisheries by-catch, and the efficiency of fishery operations have never been studied.
The researchers installed green LED lights every 10 meters in the gillnets on the Pacific coast of Baja California Sur, Mexico, and were also surprised to find that the lighting nets had all but eliminated by-catch of sharks, rays and rays, an ancient group of animals, due to a global decline due to bycatch and illegal fishing.
In addition, the lighting net reduces the time it takes fishermen to retract and untie their nets by 57%, making this technology attractive to fishermen looking to increase efficiency without worrying about by-catch. This is because fishermen need to remove fewer entangled animals in their illuminated nets, including a relatively small number of turtles, sharks, rays, rays, squid, and small fish, which are time-consuming, difficult, and even dangerous to remove from the nets.
In practice, this means that fishermen can save more than an hour per trip when fishing with lighted nets, which also helps to improve the quality of their catch.
The World Wide Fund for Nature (WWF) is working in many coastal countries to reduce bycatch of iconic megafauna in gillnet fisheries, such as dolphins, sharks and rays. Until now, however, technical solutions to reduce bycatch have been limited, and allowing fishers to continue fishing for species often has important implications for livelihoods and food security. This work provides a possible means to protect the last strongholds of threatened megafauna around the world and will be further explored as part of WWF's global marine conservation efforts.
