Gray whales are a common sight along the California coast, but now their numbers are spiking to unprecedented levels, and scientists have no idea why. Three hundred sixty-eight whales were spotted off the coast in December, up from just 182 in the same month last year.

"It could have to do with currents, it could have to do with temperature or salinity," Gray Whale Census Project Director Alisa Schulman-Janiger told CBS News. "It doesn't have to do with food because they don't eat on south- or north-bound migration."

Whale-watching outfitters are overjoyed at the sudden spike in gray whale populations. "We've seen more whales than I have ever seen in my 20 years or so of being a captain," said Dan Salas of Captain Dave's Dolphin & Whale Watching Safari. Owner Dave Anderson reported as many 75 whale encounters in December, up from 21 last year.

Researchers say that they've seen an increase in the number of calves traveling in the pods and believe that could mean good things for the once-endangered species. "It could very well mean that more are coming down because they're pregnant and ready to give birth, and others are coming down ready to get pregnant for the next year," said Schulman-Janiger.