For longline sable fishers in the Gulf of Alaska, there are few omens of doom more chilling than the enormous shadow of a whale approaching their boat. That’s because in the past several years, male sperm whales, the lone wolves of the ocean, have been behaving strangely. They have been teaming up to hunt fish right off fishers’ hooks, and every year more whales are coming to eat from the fishing line buffet, leading some scientists to speculate that they’re somehow communicating about the richness of the hunting ground and sharing tips. How do they recognize this thing that’s become the dinner bell?” asks Russ Andrews, a marine biologist with SEASWAP. To answer the question, Aaron Thode, a marine mammal acoustic specialist at Scripps Institution of Oceanography at UC San Diego, set up passive listening devices on moorings to see if the whales or the boats were making unique noises when the lines were reeled in. What they discovered was that the sound of the bubbles created by the revving of the propellers as the boat sped up and slowed down during the line-reeling process was calling the whales.