Swimmer who vanished at Lovers Point was wearing a shark deterrent. What science says about what they do — and don’t do

After a shark attack injured one of their own nearly three years ago, members of the Kelp Krawlers — who swim weekly around Lovers Point in Monterey County — began searching for something that might make the open ocean feel safer.

They turned to wearable shark deterrents, including magnetic ankle bands designed to overwhelm a shark’s electroreceptors — the sensitive “sixth sense” pores the predators use to detect the faint electrical heartbeats of nearby prey. Other products on the market rely on electrical currents...