An electrical device on a fishing line repels sharks and rays

hundreds, sometimes thousands, of baited hooks, catch commercially valuable fish. But they also catch sharks and rays, turtles and birds. This harms ecosystems. And removing the unwanted creatures takes time, can be dangerous, and may damage the gear.The size of the world’s bycatch, as such unwanted captures are called, is hard to measure. The fishing industry is huge, and much activity is unreported, unregulated and sometimes illegal. But a pertinent study published last year in estimated that only half of the animals hooked by a longlining fleet in the Pacific Ocean near Palau were tuna (the intended target). The rest were bycatch.