Paddle-boarders warned about sharks as sightings increase in Southern California

A jump in shark sightings close to Southern California shores have put lifeguards on higher alert.

A great white shark was spotted Wednesday just feet away from a paddle boarder in Long Beach.

A surf organization that monitors shark activity says nearly 30 sharks were spotted from Long Beach to San Onofre beach in just one day this week.

Down by the water, "shark advisory" signs warn beach goers to enter at their own risk. Experts say all these sightings are part of a larger trend – there are more sharks in the water. CBS News correspondent Carter Evans went up in a chopper with the Orange County Sheriff's Department to get a first-hand look.

Just minutes into their helicopter flight, they had spotted three great whites swimming in shallow water less than 50 feet from the shoreline.  This comes just one day after a group of sharks forced deputies to clear the water.

"Attention in the water, this is the Orange County Sheriff's Department. You are paddle-boarding next to approximately 15 great white sharks," warned Deputy Brian Stockbridge in an announcement to the swimmers. "Exit the water in a calm manner." 
 
Evans asked, "What was the response of the people in the water?"

"Well, unlike normal, they pretty much complied immediately," Stockbridge said. 

Many of the sharks appear to be juvenile great whites - six to eight feet long and about a year old.  There have been an unusual number of sightings this year.

"Shark populations are increasing," said marine biologist Chris Lowe. Lowe runs the shark lab at California State University, Long Beach. 

"The reason why I think we're seeing more sharks is because we've protected them. They've been protected in U.S. waters since 2005," Lowe explained. "The other thing is, there's lots of food.  So along our beaches, the sting ray populations have been kind of exploding over the last 50 years."

Even though sightings have become common, attacks are rare. A San Diego County mother was critically injured late last month after witnesses say a shark bit off part of her leg at a popular surf spot.  Lowe says sharks are not interested in eating humans, but the young babies are hugging the coast to hunt for food in a safe place. 

"We haven't seen signs of those young sharks actually being a potential threat to humans. When they're babies, they're afraid of pretty much everything, so they may not really be that different from us," Lowe said.

These shark sightings are becoming so common that Southern California businesses are even looking to cash in.

This weekend, for the first time, there will be a "shark boat tour" taking off from Dana Point, just down the coast.