In this May 21, 2016 file photo, a northern sea otter floats on its back while crushing a clam shell with its teeth in the small boat harbor at Seward, Alaska. Sea otters, once wiped out by hunting along Alaska's Panhandle, have made a strong comeback and fishermen who target shellfish are seeking relief from their voracious appetites. Sea otters eat the equivalent of a quarter of their own weight each day. (Photo by Dan Joling/AP Photo)
