To reveal a gruesome dolphin slaughter, the makers of a new documentary, The Cove, used spy drones, cameras disguised as rocks and a lot of daring. It’s about a group of activists who reveal the slaughter of dolphins by Japanese fisherman near the coastal town of Taiji, Japan. At least 2,000 dolphins are killed every year and are a major source of income. The meat is often passed off as whale meat. Dolphin killing receives less attention than whale hunts, but many scientists say their death is every bit as tragic.