NAHANT — After two sharks were spotted off the town’s coast last week, experts are urging beachgoers to be “shark smart” this summer.
At 4:47 p.m. last Monday, a great white shark was spotted near Egg Rock island. The next day at 8:37 p.m., another great white was spotted south of Nahant Bay. Both sightings were reported to the Sharktivity app, a public database of great white shark sightings regulated by the Atlantic White Shark Conservancy.
New England Aquarium Adjunct Scientist John Chisholm has tagged, tracked, and studied great white sharks since the 1970s. He maintains the Sharktivity app, looking into reported shark sightings and confirming their validity.
Every August for the last five years, Chisholm said there has been at least one shark sighting near Nahant. He said sharks swim north — sometimes up to Canada — in the late summer to find food.
“As the water temperature rises in the summer to the temperatures that they like, they start to migrate north. They’ve been doing it forever,” Chisholm said. “They travel the Eastern Seaboard looking for food. There’s been a ton of striped bass around, there’s a lot of seals around. A lot of people have the misconception that they only eat seals, but they also eat other fish. They’re just doing what sharks do.”
On June 20, a buoy operated by the conservancy detected a great white shark near Marblehead. TJ Cullinane of Lynn and Nahant Beaches told the Item that as a result of growing gray seal and shark populations in Cape Cod, smaller sharks are being pushed north.
“We’re talking 8- to 9-foot sharks that are about 15 years old, that really aren’t quite capable of taking on a seal,” Cullinane said. “Sometimes they still try, but for the most part they’re fish eaters and there’s a lot of fish in our area for them to eat on.”
Chisholm said that shark migration patterns haven’t changed drastically over the last few decades, and that the ubiquity of smartphones has made it easier to record and track shark sightings. He recommends the public check Sharktivity before heading out to the beach.
“I like to say to people, if you’re going to go to the beach, you’re going to check the weather app to see what the weather’s going to be like. You’re probably going to check to see if there’s traffic on the way there. Take a minute and read the shark safety guidelines and check Sharktivity. There may not be a shark sighting there that day, but that doesn’t mean there’s not a shark,” Chisholm said.
Additionally, Chisholm said beachgoers can keep themselves safe by not swimming alone, in the same waters as large schools of fish, at dawn or dusk, or while wearing shiny jewelry. In murky waters, Chisholm said necklaces and bracelets can resemble fish scales to a shark.
Chisholm said this summer, the vast majority of reported shark sightings turned out to be ocean sunfish, the large triangular dorsal fins of which can easily be mistaken for shark fins. Still, Chisholm recommends swimmers return to shore and alert a lifeguard if they see a fin.
“When you’re going into the ocean, you’re going into a wilderness are. Even though we think of it as our own personal recreation area, it’s wild, you don’t know what’s out there,” Chisholm said.
