When most of us think of places where great white sharks might converge, we think of locations such as Australia, South Africa, Mexico, or even California. However, a new study has found that one of the largest seasonal gatherings of white sharks is right off the coast of Massachusetts in Cape Cod.
In fact, the influx of great white sharks in Cape Cod is the first documented hotspot in the North Atlantic and may be the largest in the world.
However, experts believe it wasn't always this way. An uptick of shark sightings in the early 2010s—with three instances of shark attacks since 2012, including a fatal encounter in 2018—prompted the four-year study, as National Park officials, conservation organizations, and local residents wanted to know how big the shark population was getting.
As a result, researchers estimate that about 800 individual white sharks visited the sampling area along the peninsula’s eastern shoreline between 2015 and 2018.
It's difficult to tell for sure whether the shark population is necessarily growing. The findings could be indicative of changes in the sharks' behavior that has made them more susceptible to locating, or that they just weren't being sought out before.
But some evidence suggests that the population is indeed growing.
"Our population estimates increased with each year of our study," said shark expert Greg Skomal, a senior fisheries biologist at Massachusetts’s Division of Marine Fisheries who worked on the study, according to Scientific American. "This general trend is indicative of growing population, at the very least at Cape Cod and possibly beyond."
One theory as to why the shark population on Cape Cod may be growing is due to a soaring population of grey seals. After being eradicated from New England mostly due to commercial fishing in the early 1960s, the Marine Mammal Protection Act of 1972 made it safe for the mammals to return. It's taken decades for the population to bounce back, but it was estimated that there were more than 30,000 seals on the cape by 2017.
Seals are high in fat and a favorite prey for sharks, which were likely drawn to them by scent trails.
"What we’re seeing at Cape Cod is a reestablishment of the trophic (food) web and what it may have been like before overfishing and the slaughter of many of the animals at the top of the food chain," explained Chris Lowe, the director of the Shark Lab at California State University, Long Beach.
The California State University biology unit likewise recently completed a study to learn the habits of juvenile white sharks along the Southern California coastline, and found that they come closer to swimmers than previously thought.
Whether or not that's the case in Cape Cod remains to be seen. But in the meantime, local officials and advocacy groups have implemented safety measures in the wake of the study, such as beach signs, a flag warning system, public outreach and education, and training on how to stop bleeding in the event of a shark attack.
