Blue whales, the world's largest animals, are being seen off the Sonoma Coast in greater numbers this year as they feed on an abundance of krill, small shrimp-like crustaceans.

"It is an extraordinary whale," said Sarah Allen, a marine biologist with the National Park Service. "Their backs go on forever and then there is this little dorsal fin, and the blow that is 30 feet tall."

While blue whales swim along the California coast every year, this year the krill are unusually close to shore, bringing coastal visitors a rare opportunity.

"I have never seen them so close. There were a couple that were a couple hundred yards offshore," said Larry Tiller, a retired Healdsburg organic farmer and whale-watching docent for Stewards of the Coast and Redwoods.

Earlier this week, Tiller was at Bodega Head, which has been his preferred whale-watching perch for the past decade. Seated in a canvas chair, binoculars around his neck and metallic whale pins in his hat, he shows pictures taken of the giant whales during the past two weeks.

"This whale is 70 feet long, it was two miles out," Tiller said. "That was 10 days ago, but they are still out there."

Two blue whales have also been reported during a recent 10-day period just off Point Reyes Beach South in the Point Reyes National Seashore.

"It is a rarity, but there have been a few sightings," said John Dell'Osso, a Point Reyes ranger. "The fact is we have seen a couple (of blue whales) a couple of times, but it is hit and miss. It is not like the migrations of the gray whales. We can almost set our watches by them."

Blue whales are 75 to 80 feet long, although a century ago there were reports of whales 100 feet in length. Whaling nearly drove them to extinction.

Once they numbered 150,000 to 200,000, but now they are on the endangered species list. There are an estimated 5,300 left. The majority, some 3,300, are in the North Pacific.

This year, the reports of sightings close to shore have largely been in the Monterey Bay area, but the blue whales are also being seen in numbers off the Sonoma County coast.

In July, they start to arrive in the Gulf of the Farallons, Point Reyes and along the Sonoma Coast to feed, said Bill Sydeman of Petaluma, president of the Farallon Institute for Ecological Research.

"They will still be a few miles offshore, but they are so big that they are pretty obvious when they show up," Sydeman said.

A boat is still the best way to see the whales.

"We are seeing whales every day, but most of the time you are seeing a spout in the distance," said Chris Lawson, a Bodega Bay commercial fisherman.

"There are a lot of krill around. You can get close at times — you are not supposed to be within 1,000 feet, but when you are fishing sometimes it is unavoidable," he said. "I have been looking at them for 40 years and it is impressive."