“We get the calls starting right about now and lasting through the summer and into the fall. The seasonality of basking sharks is similar to that of great whites,” said state shark expert Greg Skomal. “We fully expect to get lots of reports this time of year.”

As spring rolls into summer, officials from the state’s Division of Marine Fisheries field calls from boaters who encounter giant basking sharks along the coastline and get the fish confused with great whites.

The latest sighting happened off the coast of Nahant on Sunday morning, when Revere resident Remo Pezzi captured footage of what he believed to be a 17-foot-long great white.


Pezzi said the large fish came close to his boat while he was out fishing with his son and father early in the morning. When he saw the white underbelly of the shark and its beady black eyes, he was sure that he had a great white on his hands.

“I saw white on the bottom, and I saw the mouth slightly open, and I saw about 17 to 18 feet of a shark,” he said. “Did I think it was a great white? I did.”

After the “petrifying” run-in, Pezzi quickly posted the video to Facebook, where it was shared more than 1,000 times. People commenting on the video debated back and forth about what type of fish was lurking in Nahant’s waters.

But after seeing the video this week, Skomal put Pezzi’s fears to rest: It was nothing more than a basking shark, likely feeding on plankton.

“Oh, yes. It’s got all the telltale characteristics,” he said, adding that they often hang out in river mouths, inlets, and bays.

According to Skomal, basking sharks have floppy dorsal fins, like the one in the video. Skomal said the white color Pezzi believed to be the shark’s underbelly was actually the inside of the shark’s open mouth.


Basking sharks feed on plankton by combing through the waters with their jaws open wide.

“People see that and think they are looking at a white shark,” he said.

These encounters have become so commonplace that the state launched a video guide on how to spot the differences between the two types of sharks.

“It’s our number one most misidentified fish when it comes to white sharks. Ninety-nine percent of all white shark reports turn out to be basking sharks,” said John Chisholm, a marine fisheries biologist for the state.

Regardless of the misidentifications, officials encourage people to keep their smartphones handy in case they spot a dorsal fin poking through the ocean’s surface this season.

Capturing images of sharks of any species — especially in the event that it is a great white — helps researchers, Skomal said.

“Ten years ago, we had to rely on descriptions, and that’s hard to do,” Skomal said. “Every now and then, one of these animals does turn out to be a white shark, and we are interested in that. Pull out those cellphones and get any kind of shots.”

As for Pezzi, he’s relieved he can go back in the water without the fear of a predator feeding nearby.

“That’s awesome news. At least finally someone figured it out. Now I can go buy jet skis and go skiing,” he said.


This is what was swimming around 6:30 this morning 500 yards or so off Nahant rockWas about 18 feet long Posted by Pezzi Service Center, Inc. on Sunday, May 10, 2015

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.