Massachusetts beaches shut down after great white shark sightings

A Massachusetts town shut down its beaches after a great white shark was sighted near a cliff on Monday afternoon, not long after a beach was cleared after a sighting as well.

It is unclear if these are two separate white sharks or the same white shark.

The Harbormaster of the town of Plymouth tweeted at about 2.30 p.m. that there had been a confirmed white shark sighting off Manomet Point, a popular spot for bird, seal, and whale watchers.

"Town beaches are closed at this time with red flags flying. Harbormaster crew to the area to investigate. Keep a sharp lookout and report all sightings," Plymouth Harbor wrote in the tweet.

In the same area, Marconi Beach was temporarily closed after a great white shark sighting at about 1.30 p.m., ABC affiliate WCVB in Boston reported.

The sighting was reported by the Cape Cod National Seashore and the Atlantic White Shark Conservancy's Sharktivity map.

White shark sightings off Massachusetts have become frequent in recent summers, but this is natural for two reasons, said George Burgess, director emeritus of the International Shark Attack File maintained by the Florida Museum of Natural History.

One, the temperature of the water near the Massachusetts coast at this time hovers just below 20 degrees Celsius -- cool enough for the sharks to be comfortable in, and warm enough for the more adventurous humans to venture into. There's bound to be some overlap and sightings as our population continues to increase, he said.

Two, due to successful conservation efforts in recent decades, the population of seal colonies, once endangered, is beginning to be re-established and this attracts great whites looking for a hearty meal.

"This is good news," Burgess said. "Our conservation efforts are working. Now, it's our job to adapt."