Multiple shark sightings on Friday have beachgoers and police on high alert.
Police in Barnstable, Massachusetts are urging beachgoers to use caution after a great white shark sighting off Barnstable Harbor on Friday morning.
All north side beaches, including Sandy Neck and Millway, are included in the warning. Police recommend that people avoid swimming at dawn or dusk or near seals.
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Barnstable Harbor is located on the inner Cape, off Cape Cod Bay. Most of the recent shark sightings have been on the outer Cape.
Surrounding towns have been notified, and Barnstable police, fire and the Massachusetts Department of Natural Resources are continuing to monitor the situation.
Anyone who sees anything is urged to call Barnstable police at 508-775-0387.
Sandwich police said a fisherman also came in to their station on Friday to report a shark outside the Cape Cod Canal entrance on the Sandwich side, also on the inner Cape.
Coast Guard Beach in Eastham was also closed to swimming for about an hour around 1:50 p.m. Friday after a shark was spotted by Cape Cod National Seashore staff.
Friday's shark sightings come a day after Race Point Beach in Provincetown and Head of the Meadow Beach in Truro were closed after sharks were spotted near shore.
On Wednesday, a 61-year-old man was bitten by a shark off Long Nook Beach in Truro. The man suffered deep puncture wounds to his torso and leg but is expected to survive. That beach is expected to remain closed to swimming at least through Friday.
Prior to this week's attack, it had been six years since a person had been bitten by a shark in Massachusetts.
In the last two days, there have been more than 20 shark sightings off Cape Cod, according to the Sharktivity app.
Cape Cod is a feeding ground for seals, which draw sharks, and authorities regularly caution people to avoid the water whenever seals are present.
Despite the public's fear of sharks, the odds of being killed by one are roughly 1 in 3.7 million, according to the National Aquarium in Baltimore.