"Something that has been missing from San Francisco Bay since World War II appears to be making a comeback: Harbor porpoises are showing up in growing numbers, and researchers are trying to understand why they're returning."
"The walkway across the Golden Gate Bridge is almost always packed with people taking photos. But Bill Keener isn't here for snapshots of the stunning views. He's aiming his massive telephoto lens at a dark shape in the water 200 feet below.
'There's a porpoise right there, coming very, very close,' he says. 'Here's a mother and calf coming straight at us.' Keener is with Golden Gate Cetacean Research, a nonprofit group focused on studying local porpoises, whales and dolphins."
Lauren Sommer reports for NPR's Morning Edition December 28, 2011.