Blue whales now like our local dives

Word to the whale-wise: Head south.

Once a rare sight south of Santa Barbara, blue whales have in recent years come to favor Southern California waters.

Whale watchers seeking a glimpse of the largest animals on Earth this summer will have the best chances off the coast of Orange and San Diego counties and northern Baja California, according to marine biologists.

"Some ebb and flow is normal for animal populations in general," said Mike Bursk, a biologist with the Ocean Institute in Dana Point. "But in the last decade there's been a noticeable shift. There's been a movement of the herd."

Dave Anderson, owner of Captain Dave's Dolphin Safari in Dana Point, has noticed the change.

"Five or six years ago, seeing a blue whale was newsworthy," he said. "If we saw a blue whale out here we were on TV, people were calling us."

Last summer he logged 440 blue whale sightings.

Capable of traveling 100 miles a day, the blue whales migrate north each summer from their winter grounds off Central America.

Their numbers along the Eastern Pacific coast have increased steadily since commercial whaling of the species was outlawed in 1966.

The blue whale's worldwide population is estimated at 10,000, though scientists say as many as 300,000 of the aquatic giants swam the world's oceans before whaling.

In the last two decades, Central California became known as "the best place in the world to see the largest animal on Earth predictably," said Nancy Black, marine biologist with Monterey Bay Whale Watch, which operates daily tours.

The blue whales were known to feed consistently in the krill-rich waters of deep Monterey Bay Canyon from July to October, Black said.

But in the last two years, the number of blue whales spotted by those aboard the company's two powerboats has dropped to between 20% and 30% of normal levels.

Black said she was relieved when they saw their first two whales of the season at the end of June.

"We kind of got used to the blue whales because they had been more predictable," she said. "Now when we see them it's going to be a bigger deal."

Scientists are studying the migration patterns, but offer few explanations for the whales' shift south. Bursk, of the Ocean Institute, said there had been little research into the causes of the shift.

"Anyone who tells you they know why the shift is taking place is wrong," he said.