The Japanese summer delicacy of roasted eel, braised with a tangy sauce and sprinkled with prickly mountain pepper, is in question as the creatures with their mysterious migrations become increasingly endangered.

Soaring demand helped put the creatures on the "Red List" of endangered species in 2014. It's even spurring poaching of similar species off the U.S. east coast.

Katsumi Tsukamoto, "Dr. Eel" of the only "Eel Science Laboratory" at Nihon University in Japan, thinks he's unlocked the secrets to eventually farming the eels, known as unagi, sustainably and profitably. Tsukamoto found out where the eels are spawning, and that helped researchers study conditions needed to raise them from the egg stage to adulthood.

Some fishermen see such farming less as competition than as a way to help save the species.