Greg Skomal: Cape’s a ‘restaurant for sharks’

Predator/prey relationship is playing out ‘right in our backyard.’

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Greg Skomal called Cape Cod a “restaurant for sharks” at his presentation at the Old Whaling Church in Edgartown Thursday night.

Skomal spent 23 years on the Island studying sharks and other marine animals, and said he “cut his teeth” as a young scientist in Menemsha. When Skomal was in middle school, the blockbuster film “Jaws” came out, and he became infatuated with the Vineyard-based movie.

In particular, he was fascinated by the role of Matt Hooper, the marine scientist in the film.

“‘Jaws’ was really what inspired me to become a marine scientist and fall in love with sharks,” Skomal said.

While working for the state Division of Marine Fisheries, Skomal said, he became closely integrated with the Island fishing community. He learned that fishermen were pulling in sandbar sharks, called brown sharks, at various beaches around the Vineyard. Skomal took this opportunity to tag brown sharks that were caught in order to study their behaviors.

Because white sharks were (and still are) so elusive, Skomal said much of the information he gleaned from his earliest studies came from dissecting dead sharks.

“You can learn a lot from a dead fish,” Skomal said. “If you cut open the stomach of a fish, you can learn what it’s eating.”

As many sharks as Skomal has cut up, he said, dissections don’t explain how sharks live day-to-day, and most important, how they hunt.

Skomal spoke before a packed audience — the $20 admission fee benefiting the Atlantic White Shark Conservancy, an organization that helps Skomal fund his research.

Skomal, a world-renowned shark expert, said understanding the predator-prey relationship white sharks have with gray seals is paramount to making sense of why the apex hunters are sometimes found so close to shore. 

“The media likes to harp on the fact that white sharks are appearing along our coastlines, saying it’s a new phenomenon,” Skomal said. “The only new aspect is they are piling up along our beaches because of the growing seal population.”

In order to understand how sharks hunt, Skomal said researchers tag sharks with sophisticated tracking devices. Skomal’s first time tagging a white shark was when one swam into a salt pond on Naushon Island. Skomal said he was living on the Vineyard when he got a call from his friend, saying the shark was trapped in the pond. He tagged the shark, only for the tag to come off once it was able to escape into open water. “I thought that was going to be my first and only chance to tag a white shark,” Skomal said. But now, Skomal and his team have tagged 171 white sharks over their 10 years of tagging.

Skomal said now that the seal population is rebounding, sharks are being drawn close to shore, where swimmers, paddleboarders, and kayakers recreate. 

“If you open up a restaurant that looks like this,” Skomal said as he pointed to a picture of a seal-laden beach, “you are going to get the customers in the gray suits.”

But Skomal said, even with intensive research, we still don’t know much about the predator-prey relationship sharks have with seals.

“This relationship is playing out in our backyard,” Skomal said. “A better understanding of this relationship will give us the tools and information necessary to protect people.”

Over the past 10 years, Skomal said there has been a relative increase in white sharks coming in close proximity to people.

“Although it is rare, strikes on people happen when sharks mistake people for seals,” Skomal said. “Keep in mind that there are less than 100 shark attacks in the world every year, and less than 10 percent are fatal.” (It’s worth noting that one of those fatalities happened on Cape Cod last summer.)

Skomal’s method of tagging sharks involves standing at the end of a boat pulpit holding a long pole with a dart-tag affixed to the end. 

Using acoustic technology, the tags transmit a high-frequency tone that is picked up by receivers situated all around the Cape and Islands. When a shark carrying an acoustic tag swims within a couple of hundred yards of a receiver, Skomal said, the tag pings the shark’s location on a cumulative data map.

Based on the data from that map, Skomal said there are “very few parts of the Cape we don’t see white sharks.”

However, the maps indicate very few sharks swimming in the area of Martha’s Vineyard and Nantucket. “Not many sharks visit the Vineyard — the outer Cape is where it’s happening,” Skomal said. “Most white sharks that come to the Island are transient animals moving through to get to the cafe.”

Regarding the most recent shark sighting off South Beach, Skomal said he has “no idea” what marine animal the dorsal fin could have belonged to. 

“It doesn’t look like a great white to me. It looks more like a hammerhead dorsal fin, but for all I know it could be an ocean sunfish,” Skomal said.

He told Islanders and seasonal visitors not to fret, as hammerheads are harmless and not a threat to beachgoers.

Skomal said although his crew and he spend countless hours tagging and tracking great whites, they have only tagged a fraction of the white sharks that inhabit the area. 

He said white sharks spend about 50 percent of their time in water less than 30 feet, but that information doesn’t help determine where, when, and how often they are feeding near populated areas.

New data collection technologies allow researchers to measure fine-scale movements of the marine predators, including posture, movement, and speed. “With these new technologies we can tell when a shark is just cruising, and when it is attacking,” Skomal said. 

Skomal said in the future, he hopes to place the tags (called acceleration data loggers) on the sharks along with cameras to determine their exact method for hunting: “We’ve got a lot to learn about these animals.”