Flashing NetLights reduce bycatch in small-scale fisheries of the Eastern Mediterranean

Set nets are used by fisheries globally and are the mainstay gear of Mediterranean small-scale fishing vessels, which represent > 80% of the region's fleet. Gear types such as bottom-set trammel nets and gillnets, thus have important socioeconomic significance. They are also used close to the coast, resulting in bycatch in foraging and inter-nesting areas utilised by Mediterranean sea turtles, with high rates of mortality. A third of sharks and batoids (skates and rays) are under threat of extinction, and, in the Mediterranean, over half have regional IUCN Red List status assessments that are more concerning than their global assessments. Bycatch in set nets contribute to continued population declines. There are also costs to fishers of hauling and handling these non-target species. Toward resolving this conflict, green LED lights ((c) NetLight) were trialled on trammel nets in a small-scale fishing fleet in Cyprus, to test their effectiveness in reducing bycatch of vulnerable species. Toward improving economic and environmental sustainability of the devices, a flashing duty cycle was incorporated in their design. NetLights reduced sea turtle and batoid bycatch by 42% and 50%, respectively, while no effect of NetLights was detected on commercially targeted (pandora and rabbitfish) or commercially threatening invasive alien species (pufferfish and lionfish). Sea turtle catch per unit effort was greater in nets that had greater proportion of daylight soaking, whether NetLights were present or not. No marine mammals, sharks or seabirds were caught. The study supports other findings globally that net illumination can reduce bycatch of threatened marine vertebrates. However, the observed reductions in bycatch were only weakly driven by NetLights and more trials with greater capacity are advised.