HOBE SOUND, Fla. -- Those visiting beaches in Martin County this week are being urged to keep a close eye on the water.
The news comes after beaches were shut down twice due to sharks.
On Monday afternoon, lifeguards shut down portions of Jensen Beach after a swimmer was suspected of being bitten by a shark.
The beach reopened Tuesday.
On Wednesday, county lifeguards shut down guarded sections of Hobe Sound and Jensen Beach after spotting sharks offshore.
The closure only lasted about 30 minutes.
Marine scientists say sharks typically follow migrations of bait fish, but these sightings come at a time when there haven't been any reports of large bait fish.
Experts say if you see bait fish traveling through the water to get out and wait for them to pass.