JUNO BEACH, Fla.  —  Thousands of sharks were seen circling a few hundred feet from the shore of Juno Beach Wednesday.

Biologists believe the sharks are spinners seen this time of year in shallow waters as they migrate north into cooler waters to look for food.

Last week, lifeguards kept people out of the waters of Delray Beach, Deerfield Beach, Boca Raton and along the shore at a park in Palm Beach after hundreds of sharks were spotted.

A University of Florida shark expert said they were blacktip sharks assembling before a northward migration. The species is not known to attack people but have been blamed for biting people.

Florida leads the world in shark attacks. Australia has fewer attacks but more fatal ones because of its great white shark population.