Shark Expert Explains Increase In Hammerhead Shark Sightings On Nantucket

There have been numerous hammerhead shark sightings recently that have forced lifeguards to close the water to the public at beaches across the south shore and have led to some incredible video caught by beachgoers.

The Current took time to speak with Bryan Legare, the manager of the Shark Ecology Program at the Center For Coastal Studies based in Provincetown, about these sightings, how common are they, why are these sharks in such close proximity to the island's shorelines, and how likely are hammerhead sharks to attack a person in the ocean.

Legare said while he wouldn’t call it common to see a hammerhead shark in the area of Nantucket, he didn’t doubt the news when he first heard it.

“It’s not something necessarily where when I heard about it I said ‘that’s not true.’ It does make sense, especially with the warmer water,” he said. “Last year or the year before there was a hammerhead spotted in the Gulf of Maine on a whale watch boat. They are occasional visitors especially to Nantucket, Martha’s Vineyard, and Long Island because those places have warmer waters than Cape Cod North.”

Legare said the water temperatures in the Gulf of Maine and Nantucket are an anomaly compared to the state averages.

“Their waters are warming faster than any other part of the ocean in the world,” he said.

Legare said these sharks could be moving north and visiting the island’s shores more frequently as the water temperature in their original habitats becomes too warm. He called it a range shift, where their habitat could either be expanding or constricting. Both scenarios ultimately present the shark with an option to move north. He added that seeing them so close to shore is just an example of how they hunt.

“Their range is expanding and if there is food up north, and as you could see in one of the videos one hammerhead is in the surf chasing after some fishes and stuff, that is where they hunt,” he said. “A lot of the social media you see around hammerheads is them chasing fishes in the shallow beach area. They are following the fish and able to get their because of the temperatures.”

Legare said hammerhead sharks are very docile and considers it very rare that one would attack a person in the water.

“It is very rare for hammerheads to bite someone,” he said. “A negative incident with them is generally after someone catches one on a line and gets bit that way. Anything with a pointy end can bite, it is just very unlikely. I have been in the water with a lot of hammerheads in tropical areas and never once did I feel nervous and if that would be an issue. They are curious but from a distance. Often when they appear they will be right on your periphery when you are diving and then they disappear.”

Legare said if the waters continue to heat up around the island, he wouldn’t be surprised to see hammerhead shark sightings become increasingly more common by beachgoers.