Watch a great white shark devour a seal off the coast of Cape Cod, shocking nearby whale watchers

A whale watching tour group off the coast of Provincetown, Massachusetts, got the view of a lifetime when a great white shark swam up to the boat and proceeded to attack and eat a seal — and the entire grisly scene was caught on video.

The predation event unfolded over the course of seven minutes on Saturday (May 20) during a tour hosted by Dolphin Fleet Whale Watch.

In a video captured by a member of the group and posted on Facebook, a 12-foot-long (4 meters) great white shark (Carcharodon carcharias) can be seen prowling near the boat. Then, suddenly, a juvenile gray seal (Halichoerus grypus) pops out of the water, only for the shark to snap it in two with its razor-sharp teeth.

"While we have a healthy population of great whites and seals on Cape Cod, predation events like this are not often sighted," Dolphin Fleet Whale Watch representatives wrote in the Facebook post. "This is the first time our crew has seen a predation in all of our collective years on the water."

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In a statement, the New England Aquarium confirmed that this marked the first great white shark sighting of the season in Cape Cod. 

During the summer, it's common for great white sharks to congregate off the coast of Cape Cod due to the abundance of gray seals living there, according to the Massachusetts Shark Research Program. These marine mammals were nearly wiped out by the mid-20th century due to hunting, but the 1972 Marine Mammal Protection Act helped gray seals rebound.

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Once gray seal numbers increased, so did the number of great white sharks feeding on them, according to National Oceanic and Atmospheric Administration (NOAA) Fisheries.

"Though white shark bites on humans are rare, this sighting serves as a reminder to beachgoers and boaters to be mindful of the presence of these ocean animals," John Chisholm, an adjunct scientist with the Anderson Cabot Center for Ocean Life at the New England Aquarium, said in the statement. "It's important to be aware of sharks' presence in shallow waters, to avoid where seals are present or schools of fish are visible and to stay close to shore when rescuers can reach you if needed."

The sighting was also documented on the Atlantic White Shark Conservancy's Sharktivity app, according to the statement.