Last month, a group of beachgoers on the eastern seashore of Nantucket Island in Massachusetts noticed what they initially thought might be a beached whale in the surf. In fact, it was the largest macropredatory shark in the sea: a great white, very much alive but apparently in dire straits.
Liza Phillips, among the people who came across the shark at Low Beach in the coastal community of Siasconset, told the Nantucket Current, “It was so helpless; we were thinking it was going to get back in itself, but it was completely beached. We said we have to step up and try to help. Definitely, there was some adrenaline involved.”
Phillips and a friend did indeed succeed – no small feat, adrenaline-fuelled or not – in pushing the great white into deep-enough water that it could swim off.
Nantucket, a major 19th-century whaling port famously featured in Herman Melville’s Moby-Dick, is part of the so-called Outer Lands, a pseudo-archipelago of necks, islands, and islets along the southern coast of New England. The northern reach of the Outer Lands is formed by the hooked peninsula of Cape Cod, which a study last year determined has become among the world’s most significant seasonal hotspots for great white sharks: A minimum of 800 individuals were recorded off Cape Cod between 2015 and 2018, comparing well with other famed great-white epicentres such as South Africa, Central California, Mexico’s Guadalupe Island, and South Australia.
The spectacular rebound of the Northwest Atlantic white-shark population off the Outer Lands is thought to reflect the legal protection of the species – the catch of which was banned at the federal level in the US in 1997 and by Massachusetts in 2005 – and the regional resurgence (not celebrated by all local commercial fishermen) of the grey seal.
These large “horsehead” seals, once widespread along the New England seacoast but almost hunted out by the mid-20th century, have recovered through conservation efforts, including the US Marine Mammal Protection Act of 1972; a 2017 study suggested 30,000 to 50,000 in southeastern Massachusetts waters. And they happen to be favoured prey of Northwest Atlantic great whites, which the Massachusetts Division of Marine Fisheries notes graduate from a youthful diet of striped bass and other fish to one heavy on the marine mammals – not only pinnipeds, but also dolphins, porpoises, and scavenged whale carcasses – as the sharks get older and bigger.
Research suggests many Northwest Atlantic white sharks undergo seasonal migrations between summer haunts off the New England and Canadian coasts and winter range along the southeastern US seaboard, including into the Gulf of Mexico. As Massachusetts Division of Marine Fisheries scientist and head of the Massachusetts Shark Research Program Greg Skomal told the Nantucket Current last year, Nantucket appears to be “more like a highway” for great whites beelining for prime seal-hunting grounds off Cape Cod’s Outer Cape rather than a primary hangout. That said, sightings along the island’s sandy shores – especially its northernmost reach, the tip of a barrier-beach peninsula called Great Point – have also been on the rise. In July 2023, multiple seal-predation events in the Great Point vicinity (including –you’re forewarned – this rather graphic one) prompted authorities to enact a temporary ban on swimming out of an abundance of caution.
Great whites are the highest-profile sharks cruising Nantucket waters, but not the only ones. A couple of months ago, a dusky shark snacked on a seal off Great Point (which we wrote about earlier this month). This past June, meanwhile, the carcass of a tiger shark – an unusual occurrence for that warm-water species so early in the Northern Hemisphere summer – briefly washed ashore on the island before being swept out to sea again:
An unusual & sad sight on the south shore this week. A tiger shark washed up dead on Tuesday.
— Nantucket Current (@ACKCurrent) June 7, 2024
It is relatively rare to see a tiger shark in the waters around Nantucket, and especially in spring when water temperatures are still low. pic.twitter.com/WpKNVtOYua
Such washups of dead sharks, and the beaching of still-living sharks such as the recent Nantucket great white, aren’t as commonly reported as strandings of marine mammals, sea turtles, and seabirds. A 2022 Fish & Fisheries paper titled “Global Assessment of Shark Strandings” took this comparatively under-studied phenomenon under consideration, examining 3,150 records between 1880 and 2021 to offer some much-needed insights.
That assessment found that the top three shark species reported in stranding events are leopard sharks, brown smoothhounds, and salmon sharks. Whale sharks – the biggest of all fishes – are next on the list. Great whites land at No. 10. The US, New Zealand, the UK, and South Africa account for the majority of reported shark strandings.
Because many beached sharks are already dead – and frequently quite decomposed – the ultimate cause for the situation is often unknown. But the study does pinpoint some significant triggers for shark strandings, including diseases such as meningoencephalitis, the culprit in numerous mass beachings of, for example, salmon and leopard sharks. There are lots of other potential reasons: Among other conditions and situations, sharks may strand because of bodily injury (as from fishing gear or predation), find themselves trapped after the tide ebbs, founder when they pursue prey into shallows and breaking surf, or wash ashore after sudden, drastic changes in aquatic oxygen content or temperature.
One of the Fish & Fisheries paper’s co-authors, Dr. Natascha Wosnick, lead scientist of the Shark Research and Conservation Program at the Bahamas-based Cape Eleuthera Institute, told me by email that the rescued white shark on Nantucket was a juvenile or subadult. Although claspers – the mating-related structures behind the pelvic fins of male sharks – aren’t readily discernible in the clip, it’s difficult to definitely say whether the animal in question is male or female. (Claspers can be quite small in juvenile male sharks.) Female sharks accounted for the majority of the stranding cases analysed in the study for which sex was recorded, but Wosnick said “many records lack this data type, hindering our ability to better understand potential patterns.”
Those recorded strandings paint a pretty grim picture when it comes to survival rates: Only 9.9 percent of stranded sharks – which don’t survive long outside (or mostly outside) water, for multiple reasons – were found alive, and 94 percent of those didn’t survive. The study notes that “delayed mortality” likely resulted for at least some of the small fraction of stranded sharks successfully returned to the ocean, given the majority of live beached individuals are in a moribund state.
“What they did was incredibly brave and may have saved the shark’s life but it was also extremely dangerous.”
That said, Wosnick notes that the Nantucket great white appears “very responsive” in the footage and doesn’t necessarily look sick. “It’s possible that it was chasing prey and ended up in shallow waters,” she notes. “Juveniles often exhibit this kind of learning foraging behaviour, which can lead them into risky situations – this might be one such case. However, it’s impossible to know for sure.
“Typically,” she added, “if an animal is seriously ill, it tends to strand again nearby after being rescued.”
What should you do if you find yourself in this sort of rare situation, encountering a great white or other good-sized shark thrashing in the surf or marooned in the swash? The commendable actions of the folks in the Nantucket case aren’t without risks. “What they did was incredibly brave and may have saved the shark’s life,” Wosnick said, “but it was also extremely dangerous. It’s a difficult balance because, on one hand, we want to encourage people to help in these situations, especially since sharks can die within minutes out of the water. However, with species that large, the risk of being bitten or injured is significant, especially if someone has never handled a shark before. Unfortunately, we can’t recommend that people try to rescue stranded sharks themselves. Instead, it's safer to call the authorities and, in the meantime, try to keep water circulating through the shark’s gills to give it a chance.”
The dearth of shark-focused rescue and rehabilitation programs is another problem area Wosnick and her co-authors identify when it comes to strandings. “It’s important to advocate for governments to establish rescue centers and invest in training,” she said, “so dedicated rescue initiatives can be developed for sharks, similar to those we already have for other marine animals.”
Indeed, the paper notes that available survival stats suggest stranded sharks may be more vulnerable than some other marine animals. And, needless to say, with more than a third of shark species considered at risk of extinction – from overfishing, climate change, and other anthropogenic threats – strandings, both as a cause of mortality and a source of information that might contribute to shark conservation, shouldn’t be overlooked.
Top header image: Shutterstock
Whales and Dolphins
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