On a longline fishing boat off the Galapagos Islands, a concerned biologist working undercover as a cook films a horrifying scene. As the camera rolls, a blue shark is dragged upside down out of the water, a sharp hook piercing it through the roof of the mouth and out through the side of the face...

Flying back and forth over Cape Cod Bay, a survey plane spotted a half dozen of the world’s rarest creatures: North Atlantic right whales. Such sightings are good news. The species hovers near extinction—by one estimate, fewer than 360 remain. Each time researchers locate a whale, they take pictures...