Wellfleet, Mass.The ocean was flat and black during Arthur Medici’s memorial. Dozens of surfers went in with flowers on their boards, a “paddle out” for Medici that many, including the Atlantic White Shark Conservancy, thought wasn’t the best idea—there were still sharks around in late October. Organizers had hoped to secure a spotter plane to scan for great whites, but the sky was a blanket of thick, leaden clouds.

Seals popped up in the surf close to shore, their dark eyes surveying the beach. “They're going out there?” a striped-bass fisherman down the beach asked as he watched them go.

One month had passed since Medici, 26, was killed on Newcomb Hollow Beach in Wellfleet, Massachusetts, the victim of the state’s first fatal