Even by deep-sea standards, Greenland sharks are weird. The Arctic-dwelling fish live for centuries, the longest lifespan of any animal with a spine. Where and when they breed are mysteries. Many have wormy parasites dangling from their eyes. But just like other sharks, they\u2019re frequently hooked as by-catch, contributing to the 50 million sharks unintentionally caught around the world every year. Helping these quirky sharks avoid the hook, however, is proving challenging.<\/p>\n
The sharks are falling victim to the turbot fishery off Baffin Island, Nunavut. This fishery uses longlines with hundreds of wickedly sharp hooks baited with squid to catch flat, meter-long turbot that hang out on the seafloor. In 2009, changing ice conditions forced the fishers to switch from a winter fishery to a summer one\u2014precisely when the sharks spend more time close to shore. That year, shark by-catch skyrocketed\u2014fishers snagged 4.3 tonnes of Greenland shark for every tonne of turbot. Losing sharks to by-catch is bad for the sharks, but it\u2019s also bad for the fishers, who lose their gear and miss out on valuable turbot.<\/p>\n
In the early 2010s, a promising technology, called the selective magnetic and repellent-treated (SMART) hook, was developed by SharkDefense, a group of researchers based in New Jersey. The hook creates a magnetic field, which interferes with some sharks\u2019 electrosensory organs and may keep them from coming too close. Previous studies on the SMART hook showed it repelled spiny dogfish<\/a> and bonnethead<\/a> sharks from other longline fisheries, so Scott Grant, a biologist at Memorial University in St. John\u2019s, Newfoundland, thought it might work for the Greenland sharks, which rely on their ability to sense electric fields to navigate and hunt in deep, dark waters.<\/p>\n