Hundreds of sharks are congregating in the waters off Pasco County, Fla., on the Gulf Coast, with scientists and swimmers wondering why.

The Pasco County Sheriff's marine patrol has spotted bull sharks, hammerheads and nurse sharks — and some are ten feet long.

A sheriff's spokesman says an alert has been issued to keep boaters and swimmers out of harm's way. No one has been bitten.

Scientists may go to Anclote Key to investigate what's attracting the sharks. They say the gathering is quite unusual.

The sheriff's office speculates that the shark congregation may be because a nearby power plant discharges warm water that attracts smaller fish.