According to James Sulikowski, a shark expert at University of New England in Biddeford, great white sharks and the beach goers they sometimes scare have a lot in common.

“They’re a lot like human beings,” said Sulikowski, a professor of marine sciences at the school. “They grow very slowly. They live to an older age, they don’t reach sexual maturity until an older age, and they produce relatively few offspring.”

Of course, one of those species is a serious threat to the survival of the other. Humans kill an estimate of 100 million sharks every year — sharks, in contrast, kill an average of five humans worldwide annually.

On Saturday, there were three reported sightings of great white sharks off the coast of Maine, coinciding with the 40th anniversary of the release of the movie “Jaws,” a Hollywood horror that made the razor-toothed predator nature’s best-known villain.

“White sharks are going to be expanding their range,” Sulikowski said. “We see them down in the Cape, because there’s a food source there. There’s an abundance of seals in Maine, so it’s only natural for white sharks to be venturing out and looking for niches and food sources. What does that mean for us? It means we have a large, charismatic species in our environment.”

By Monday, Sulikowski and others had largely concluded that the animals sighted on Saturday were more likely the massive — but peaceful — basking sharks, not white sharks.

But the scientist said Mainers should be hoping for more sightings of the predatory beasts, not less of them. For starters, that could be a sign the sharks, who are classified as threatened, are growing into a healthier population.

And thanks to their similarities with humans, it takes a long time for white sharks to grow into a healthier population.

“If you start hunting and killing these animals before they reach sexual maturity, their populations will plummet,” said Sulikowski, noting that many white sharks don’t have offspring and replace themselves in the population until they reach their 20s. “They’re not made to rebound from our interactions with them, and that’s a major issue that we’re dealing with.”

Why would Mainers want a healthier population of great white sharks off their coast?

Healthy great whites lead to healthy seals

“The sharks keep the oceans clean and play important roles as apex predators,” Sulikowski said. “Their role is essential to making the ecosystem stronger.”

As counterintuitive as it may seem at first, he said a healthy great white shark population leads to healthy populations of seals and other sea animals the sharks typically eat.

“They definitely are sleek, they’re built for speed and they’re built to be the apex predator, but they are really attracted to dead, dying or injured prey items,” he said.

Great white sharks thrive by eliminating the weakest prey available, gobbling up creatures who might otherwise pass on those traits to offspring, effectively “strengthening the gene pools” of seals and other marine animals, Sulikowski said.

According to the data, the sharks won’t attack you.

Never in the history of Maine or New Hampshire has there been an unprovoked shark attack on a human.

“White sharks’ diet is so highly specialized — they’re really looking for what’s going to give them the most bang for their buck, and that’s fat,” Sulikowski said. “They’re looking for prey like whales and seals.”

In the cases where swimmers are attacked, he said, “we’re in their environment and [the sharks] get confused. Most shark attacks are bite-and-release. They bite into us and they realize immediately that this is not what they want to eat, and they let go. But all we see are the stitches on the news afterward.”

Even with human obesity statistics heading in the direction they are, people can’t compete with whales as a fatty food source for sharks.

Every year, an average of between 40 and 50 people die from lightning strikes in America — almost 10 times as many as die worldwide from shark attacks.

“You’ve got a better chance of being bitten by another human being or a dog than a shark,” Sulikowski said. “You have a better chance being killed by a bee sting.”

If you see a huge fish with a dorsal fin sticking out of the water, there’s a good chance it’s not a great white.

In one of the three reported great white sightings, a man fishing about 26 miles off the coast of Portland said he saw a shark pull up alongside his vessel — and that it was about the same length as his 22-foot boat.

“Everybody froze,” fisherman Kevin Proctor told Portland television station WGME, CBS 13. “We were in shock.”

According to the Canadian Shark Research Center, the largest great white shark ever accurately recorded was a 20-footer caught in 1988 off Prince Edward Island, although unproven tales of 22- and 23-foot great whites have popped up around the world over the decades.

“Basking sharks are big — they’re bigger than white sharks,” Sulikowski said. “If you were to overlay a white shark with a basking shark, you’d find they’re nearly identical. But if you look closely, you can see some differences. The dorsal fin of a basking shark is more rounded at apex, while the white shark’s is more pointy. Some of the video that’s been going around clearly shows a more rounded fin.

“Plus the size,” he continued. “People are talking about lengths of 26 or 27 feet. A large white shark typically falls in the range of 15 or 16 feet.”

Basking sharks, by comparison, are the world’s second largest fish, regularly reaching the 20-26-foot range.

Great white sharks deserve more study.

“Sharks need our help,” Sulikowski said. “One of the things we can do is understand their biology — we need more research into this species and into their habitat, so we understand where they go and why they go there, so we can change our behaviors to respect that.”

Sulikowski noted that the solution to reducing shark-human interactions is to give the white sharks more personal space, not vice versa. If people understand the still enigmatic great whites better, they can determine how to keep out of the animals’ way, the scientist reasoned.

“Sharks don’t listen to us,” he said. “They don’t care what day it is, or what season it is. They just want to eat and reproduce.”

Maine waters aren’t too cold for great whites.

A common misconception that prevailed for years was that waters off the coast of Maine are too cold for white sharks, but with more regular sightings here, that myth seems to have dissolved somewhat in recent years.

“The range does go that far north, and there have been some fairly large great whites caught off Canada,” Nancy Kohler, a Rhode Island-based shark researcher with the National Marine Fisheries Service Apex Predator Program, told the Bangor Daily News in a previous interview. “The water’s not too cold.”

The massive razor-tooth fish was made one of nature’s best known villains in the 1975 Steven Spielberg horror movie “Jaws,” and is listed by the cable network Animal Planet as the natural world’s No. 1 predator — ahead of lions, grizzly bears and crocodiles.

Kohler said great whites can be found in waters as cold as the low 50s. According to the National Oceanographic Data Center, the average ocean water temperatures from Portland to Bar Harbor remain in the 50s from June through October.

So as long as there are great whites out there, they’ll come up along the coast of Maine. Sulikowski and others argue that’s good news for Mainers.

Seth has nearly a decade of professional journalism experience and writes about the greater Portland region.