Only 51 of these U.S. whales remain. Little has been done to prevent their extinction

Rice's whales are one of the most recently discovered whale species in the world — and already one of the most endangered. But protections for the Gulf of Mexico species have been repeatedly delayed. (KL Murphy for NPR)

Even before they saw one of the rarest mammals in the Gulf of Mexico, the two amateur fishermen were already feeling lucky. They had motored to their favorite spot 35 miles off the coast of Pensacola, Fla., downed a couple Miller Lites, and caught their third mahi mahi when they heard the sound of air escaping a blowhole.

"Then you start looking," said Ben Renfroe, who grabbed his phone to film it. "Is that a dolphin or a whale?"