We asked Swampscott, Salem and Marblehead Patch readers to take a shot at identifying what kind of shark it was and several of you answered correctly — a blue shark.
Tony Lacasse, media relations director for the New England Aquarium, watched the video and confirmed it was a blue shark.
The director said they are by far the most common large shark in these parts during late summer. They are migratory and chase schooling herring, mackeral, blue fish and striped bass.
They are commonly five to seven feet long but can grow much larger.
Two years ago off Gloucester, a Massachusetts teen caught a 12-foot, 458-pound blue shark.
And two years ago, in September, a big blue shark — 8 feet, 250 to 275 pounds washed ashore near the Nahant/Lynn line, the director said.
Blue shark are a timid species but they have been implicated in a few attacks involving people around the world.
If you see a dorsal fin you need to get out of the water, evacuate the beach, experts advise.
Three weeks ago, Wallis Sands Beach in Rye New Hampshire closed for the afternoon after a spotting of what was believed to be a blue shark, Lacasse said.
The upper body of a blue shark is gray with a bluish hue, Tony Lacasse said.They are thin with a pointed snout and swim fast and in irregular patterns. There has not been a fatal shark attack in New England since 1936 – over 75 years.