Biologist Roger Payne heard about the stranded porpoise one night in 1964, while listening to a local radio station as he worked in a lab at Tufts University. Wanting to see for himself, he drove to nearby Revere Beach, north of Boston, and found the animal’s body. The porpoise had been mutilated...

You don’t forget the images: the olive ridley sea turtle, a plastic straw lodged in his nose. The Rubenesque sea lion, neck cinched tight by a thick plastic packing strap. The Cuvier’s beaked whale, stomach split open to reveal more than 80 pounds of plastic waste—snack bags, rope, rice sacks...

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...