HARPSWELL — Local marine biologists believe the shark attack that killed a woman in Harpswell on Monday may have been the result of mistaken identity.
Sharks who attack humans often do so only if they feel threatened or mistake a person for one of their normal food sources, according to Steven Allen, a marine biologist and assistant director of Bowdoin College’s Schiller Coastal Studies Center on Orr’s Island in Harpswell. From the bottom, a shark is only going to see a shadowy outline splashing in the water and assume it’s a seal, he said.
Some scientists hypothesize that there will be more great white sightings in the area as the Gulf of Maine continues to warm, but Tobey Curtis, fishery management specialist of the Atlantic Highly Migratory Species Management Division for the National Oceanic and Atmospheric Administration Fisheries, is not convinced.
“Understanding the effects of climate change on fish populations, including sharks, is an emerging area of study and a priority for NOAA Fisheries (but) there is currently no evidence that white sharks or other species are spending more or less time near shore as a result of warming waters,” he said. “There is also no reason to suspect warming waters would bring more white sharks to the region; they are already there.”
According to Curtis, white sharks have been spotted in Maine for decades, particularly in the summer and fall months, and any lack of encounters with humans simply indicates that they are ignoring us and hunting their natural prey, he said.
“Food availability, more than water temperature, influences where the sharks hang out during these seasons,” he said. “Locations with abundant seals in particular will more frequently attract white sharks.”
That’s not to say that warming waters won’t have any impact on the sharks.
There are plenty of seals in Maine, and Allen said this year he has noticed more than ever. This could be the result of a combination of increased food supply and fewer tourists and swimmers spending time in the water due to the pandemic.
“I think it’s a bit of a chain reaction,” Allen said. “The waters are moving more prey species up, and they’re following the food source. … There are more fish and the seals are going to eat the fish. It’s one long chain that’s all connected.”
David Carlon, director of the Schiller Coastal Studies Center, said that while the attack was “surprising and very tragic,” it’s been known for some time that great white sharks like to hang out in Maine waters during the summer months. Sulikowsky told the Press Herald last year that there were seven sightings in 2018, up from two in 2017 and one in 2016.
If anything, Carlon said, given the bounty of prey and the competition further south, it’s surprising there aren’t more sharks, though a lack of sightings doesn’t necessarily mean sharks aren’t present.
“We know there are plenty of seals, so when are the sharks going to figure it out?” he said.
With sightings and attacks so rare, there are very few data points and even more uncertainty, he said.
Still, there are ways to minimize the risk of an attack, though Curtis stressed that “this kind of encounter is extremely rare.”
“White sharks do use topography to their advantage when hunting their natural prey, like seals and porpoises. … (Sharks) are ambush predators, and prefer to surprise their prey from below. Steep drop-offs in the seafloor adjacent to areas where there are aggregations of natural prey are places white sharks naturally patrol,” he said.
Sharks, especially large ones, tend to dislike shallow water, despite a famous scene from the movie “Jaws,” Carlon said, and Allen cautioned people to stay away from areas with a lot of ledges, as they are popular seal “haul outs.”
“Swimmers and surfers can reduce their chances of encountering a shark by avoiding turbid waters, areas where schools of fish, seals, or dolphins are present, or areas where people are fishing,” Curtis said. “Removing jewelry before going into the water and swimming in groups can also reduce the chance of an interaction.”
Despite Monday’s fatality, attacks on humans are rare and often accidental, and Carlon asked that people focus on how to safely use the water instead of how to get rid of sharks.
“They’re an important group ecologically and it’s stunning what the impact of humans has been,” he said. ‘They’re being fished out.
“It doesn’t take anything away from (the tragedy), but hopefully people don’t go out and kill sharks.”
Tobey Curtis works in the Atlantic Highly Migratory Species Management Division. This article has been updated to correctly name the division.
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