(CBS 8) - They are the largest animals to have ever lived on earth. Endangered blue whales are being spotted off the coast of Orange County.

The blue whales are appearing offshore earlier in the year than usual, and in huge numbers, from Dana Point to right here in San Diego. While these magnificent creatures were nearly hunted to extinction 50 years ago, now more than 2,000 of them spend their summers off California's coast.

A whale-watching boat captain says this is, to his knowledge, the first breach of blue whales in these waters. He says last week 54 whales were spotted off Dana Point feeding on tons of shrimp-like krill at the ocean's surface.

Last weekend, a paddle boarder two and a half miles off Dana Point got an up-close and personal look at a blue whale, estimated to be 80 feet long.

These blue whales are also putting on a show in local waters as well, according to Adventure Rib Rides, which offers blue whale watching tours. On Wednesday, the tour's guide says passengers saw more than 24 blue whales off San Diego's coast.

So what's behind this increase in the numbers of blue whales? Some scientists say the whales are changing their migration patterns to feed on krill, whose own population has exploded off California's coast over the past few years.