In recent years, the great white shark population off the coast of Cape Cod has appeared to be booming. And thanks to a recent study from the Atlantic White Shark Conservancy, we now know it to be true.
The first-of-its-kind study conducted in Cape waters has shown that the area isn’t just popular among great whites – it’s one of the largest hotspots for great white sharks in the world.
Through their research, scientists determined that some 800 great whites visited Cape Cod between the years 2015 and 2018. These numbers are staggering, to say the least, as they’re “comparable to but larger than” populations off the coast of South Africa, South Australia, central California, and Guadalupe Island, Mexico.
Over the course of 137 trips to Cape beaches, researchers collected close to 3,000 shark sightings on video, using mark-recapture methods to estimate the full size of the hotspot.
Scientists used unique pigment patterns to identify great white sharks
In studies past, researchers counted sharks by luring them to a boat with bait. This method didn’t provide the most reliable numbers, however, as juvenile sharks stay close to the coast rather than hunting with older individuals.
So, rather than counting sharks on the hunt, they identified individual sharks by their pigment patterns, a unique characteristic similar to fingerprints.
“Mark-recapture methods use repeated surveys of uniquely marked animals to estimate population size,” researchers said in the study. “In the case of white sharks, individuals can be distinguished based on unique markings and notches in their dorsal fins.”
After using a pilot to spot the sharks, researchers approached the animals, collecting underwater footage with a GoPro without disturbing them. In total, they identified 339 individual white sharks.
“The estimate provides an important baseline that can be used to monitor the performance of conservation measures for the broader population, which declined by as much as 80% as fishing pressure increased in the 1970s and 1980s,” said lead author Megan Winton.
“Cape Cod is the only area in the region where researchers can feasibly monitor the population, and our estimates suggest that the Cape is among the larger white shark hotspots worldwide, which is good news from a conservation standpoint.”
Cape cod’s great white population peaks in late summer
In their research, scientists found that the white shark population peaks in late summer and early fall, when ocean temperatures are warmest. That said, though they recorded around 800 sharks total, this doesn’t mean 800 at any given time.
“Their movements are very dynamic,” explained shark researcher Greg Skomal. “They trickle in and out. Some white sharks simply stop by on their way north while others spend more time along the Cape, likely because they have success feeding on seals.”
As water temperatures reach their peak this year, experts anticipate the return of “dozens to hundreds” of white sharks. And though shark attacks are extremely rare, it’s always best to exercise caution. Great white sharks are “very cautious, selective predators,” but mistakes can and do happen.