‘Hammerheads are the celebrities of the moment’

The occasional spotting of a hammerhead shark off of Martha’s Vineyard and Nantucket has become a more common shark sighting this summer, including when a pair of hammerheads shut down a beach to swimming earlier this week.

The warm-water species visiting the Massachusetts region more and more could be a sign of things to come, according to a local shark expert, predicting that other warm-water sharks will also come here as the ocean heats up.

“It wasn’t unheard of before to see one (hammerhead) on the southern side of the Islands, but it’s unusual to see how many we’re seeing close to shore now,” said John Chisholm, who is with the New England Aquarium and has been tracking shark sightings for the Atlantic White Shark Conservancy.

“We’re seeing more and more coming closer and closer to the Islands,” he added. “Hammerheads are the celebrities of the moment.”

The latest hammerhead sighting was off of South Beach in Edgartown on Monday, sparking the beach to temporarily shut down to swimming. A drone photographer took a shot from above, showing a pair of hammerheads near the beach.

The hammerheads’ favorite spots around here have been on the southern side of Martha’s Vineyard and Nantucket. Earlier this summer, a hammerhead was spotted off Nantucket’s Cisco Beach.

Hammerheads have even been spotted around Chatham’s Monomoy Island, a hotspot for great white sharks.

“This has historically been the northern extent of their range in the summer,” Chisholm said. “We know this is a warm-water species, and as the water gets warmer up here, they’re extending their range.

“As the waters warm, we can expect to see more species like this,” he added, noting that blacktip and spinner sharks could be some of those warm water species migrating north.

Tiger sharks are now migrating farther north each year because of climate change and warmer oceans, according to a study released earlier this year.

While great white sharks hunt for seals close to shore along the Cape, hammerheads are fish eaters and enjoy feasting on striped bass.

“They’re not really a danger to humans, but they do have the potential to bite,” Chisholm said, explaining why beaches have been closing to swimming following a hammerhead sighting.

Around the world since 1900, there have been a total of 16 reported hammerhead bite incidents of people, according to the International Shark Attack File. The most of those “unprovoked” shark attacks happened along the Florida coast, and none of the 16 hammerhead bites were fatal.

Great whites account for the most reported shark bites, with a total of 354 incidents, including 57 fatal bites. Tiger sharks are next with 138 total incidents, including 36 fatal bites.