It was a balmy Friday morning in June when Domenic Biagini, whale-watching tour captain and wildlife photographer, steered his 25-foot boat out of San Diego's Mission Bay with six clients on board. The plan was to find some whales—perhaps a migrating blue whale—so he radioed Lisa LaPointe, another tour captain, to see if she’d seen any that day.

“Dom, we just saw a pearly white, 15-foot animal that didn’t have a dorsal fin,” he recalls her saying over the radio. “This is the pearliest white you can imagine.”

It definitely wasn’t a blue whale. Or a humpback or an orca, or any of the other species he usually sees while out on a whale-watching trip. What she was describing sounded like a