PALM BEACH, Florida (CBSMiami) - The beaches are open Thursday in Palm Beach County following several days of shark scares near the shore.

For the last two days, beaches were shutdown after thousands of sharks were spotted swimming close to the shoreline.

The marine predators, mostly blacktip and spinner sharks, have been spotted from Boca Raton to Jupiter since the start of the month.

Shark sightings off South Florida are not uncommon this time of year. Marine biologists say the sharks are migrating north.

Wednesday, sharks caused the closings at three Palm Beach County beaches.

Once a shark appears near the shore, a lifeguard will close the beach and keep it closed until half hour after the last shark is spotted.

If you're swimming at a South Florida beach, be sure to swim along beaches where lifeguards are present. Also, leave your jewelry on the shore. Scientists say sharks are attracted to silver, along with the colors yellow and gold.