Fin Whales, Once Rare, Crowd Calif. Coast

Tracking a mystery, Alisa Schulman-Janiger and other marine biologists follow an ocean footprint looking for the second largest mammal in the world, the fin whale.

Sightings of the fin whale - part of the family that includes the humpback and big blue whales - used to be a rarity in the Santa Monica Bay but not anymore. They're everywhere, reports CBS News Correspondent Sandra Hughes.

"The people who have done this, watching for 20, 25 years, have never seen anything like it," Schulman-Janiger, a marine biologist at the American Cetacean Society, told Hughes. "It's described as a forest of blows. Everywhere you look there are these columns of blows going into the air."

Marine biologists started tracking the fin whale for a census beginning Dec. 1, 2009.

"We've seen them 31 out of 31 days, so it's amazing," Schulman-Janiger told Hughes. "I don't know how long this is going to continue, but it's absolutely fabulous."

In 2005-06 season, fin whales were seen on four days, according to the American Cetacean Society. By the 2007-08 season, they were sighted on 41 days. In the 2008-09 season, fin whales were seen on 91 days.

"Not just this concentration of the fin whales and blue whales and the humpbacks, there has been a smorgasbord out there," boat Capt. John Glackin told Hughes.

In 2007, marine biologists noticed a large number of giant blue whales had taken up residence off Southern California shores instead of migrating past as they usually did. They stayed to feed off a still unexplained population explosion of krill, small shrimp-like fish.

"It's possible that this is in response to some greater thing that's happening because of global climate change," David Bader of the Aquarium of the Pacific told Hughes then. "It could just be a variation in a natural cycle."

Marine biologists tracking the fin whale say it's again the krill population that has kept these whales here.

"We've have so many whales feeding and so much preponderance of the krill and the small fishes they like," Schulman-Janiger told Hughes. "I think there's a lot of good stuff going on with the ecosystem here."

Once a highly polluted coastal area, the Southern California coast has gone through a number of clean-up efforts scientists believe have worked. Sea life is re-populating, creating new patterns of migration that are both mystifying and magnificent.