As I coiled rope on the deck of a commercial fishing boat in the western Gulf of Alaska, I felt the sudden thud of a revolver reverberate in my chest. I wheeled around as a crewmate fired more bullets; a round of buckshot followed, from a shotgun held by my captain. I’d known their anger was growing as sperm whales ate our catch but hadn’t expected they would vent their frustrations with live ammunition. I looked out and saw a sperm whale crest the surface for air around 20 meters away, seemingly unfazed by the heavy fire.
It was early spring 2013, and I was sore, exhausted, and cold. After working 20 hours a day for more than a week, my crewmates and I still owed the boat money because sperm whales had dined on nearly all the sablefish hanging from our hooks as we burned fuel and ate food—both of which came out of our pay. We were using longline gear, essentially a kilometers-long rope with baited hooks spaced at intervals, and all that we pulled from the depths were bent hooks and the occasional disembodied sablefish head.
In videos taken by researchers over the years, the whales are surprisingly graceful—giants weighing 15 to 40 tonnes gently biting half-a-meter-long sablefish off the hooks. Sometimes sperm whales will rake the rope as it’s being hauled in, letting the hooks run over their lower teeth, with the fish popping off upon contact. Other times, the whales will grab a taut rope in their mouth and pluck it like a guitar string, whipping fish off the hooks from the vibration.
Fatigue and financial loss made me indifferent to the agile intelligence displayed below my feet, but seeing my coworkers shoot at the largest species of toothed whales on the planet—an illegal act that could lead to a steep fine and a year in jail in the United States—revolted me. Yet I knew my protests would be futile, and I was more than a day’s boat ride from the nearest port.
In the Gulf of Alaska, as well as in longline fisheries throughout the world from the Bering Sea to the Antarctic and tropical waters between, toothed whales—that is, any whale that feeds with teeth instead of baleen, such as sperm, pilot, and killer whales—are learning to see fishers and their gear as a source of an easy meal. Scientists researching this behavior, known as depredation, say whales are increasingly eating lucrative catches right off the hook instead of foraging naturally. There’s no easy way to stop it, and the behavior is spreading through whale culture. Whales’ penchant for hooked fish might be the biggest fisheries story that hardly anyone knows about.