Sharks near Cape Cod
There are diverse shark populations in the coastal waters of Cape Cod, a peninsula in the US state of Massachusetts extending into the Atlantic Ocean. The region has become a focal point for shark research and public interest due to a significant increase in sightings, particularly of great white sharks (Carcharodon carcharias), driven by ecological shifts, notably the recovery of gray seal populations following the Marine Mammal Protection Act of 1972.[1][2]
Geography and habitat
Cape Cod, located in southeastern Massachusetts, is surrounded by Cape Cod Bay to the north, Nantucket Sound to the south, and the Atlantic Ocean to the east. Its nutrient-rich waters, influenced by the Gulf Stream and Labrador Current, support a diverse marine ecosystem with abundant prey like gray seals (Halichoerus grypus), Atlantic mackerel (Scomber scombrus), and other fish species.[3] The Outer Cape, including towns like Provincetown, Truro, Wellfleet, and Chatham, is a hotspot for shark activity due to shallow, sandy-bottomed waters and dense seal colonies, particularly at locations like Head of the Meadow Beach and Monomoy Island.[4][5] Seasonal water temperature changes (ranging from 10 °C to 20 °C) attract migratory sharks in summer and early fall.[4]
Ecological role
Sharks, including dusky and white sharks, are critical apex predators in Cape Cod's marine ecosystems, regulating prey populations like seals and fish to maintain biodiversity and prevent overgrazing of vital habitats such as seagrasses. A 2025 study documented dusky sharks preying on gray seals off Nantucket, indicating their recovery and resumption of a historically significant ecological role.[6] White sharks, recognized as keystone species, further enhance ecosystem stability by controlling seal populations, with their resurgence in Cape Cod waters marking a conservation success.[7] Sharks also facilitate nutrient cycling across ocean regions, boosting productivity. The recovery of species in and around Cape Code, driven by rebounding seal populations, underscores their role in coastal ecosystem dynamics and carbon sequestration, necessitating continued conservation amid climate change and human impacts.[8]
Human interactions
Sightings and Safety
Shark sightings, especially great whites, have increased, with over hundreds of annual reports, peaking June–October.[9] There are shark sightings by air.[10] The Atlantic White Shark Conservancy (AWSC) uses tagging and the Sharktivity app for real-time monitoring.[7] Safety measures include purple shark flags, temporary beach closures, and education campaigns.
An estimated 800 white sharks visited the Cape from 2015 to 2018.[11]
Attacks
Shark attacks are rare but have increased since the 2000s due to a rebounding gray seal population attracting great white sharks. In 1936, Joseph Troy Jr., a 16-year-old, died after a great white shark attack in Buzzards Bay off Mattapoisett, and in 2018, Arthur Medici, a 26-year-old, was killed by a great white while boogie boarding at Newcomb Hollow Beach, Wellfleet.[12][13] There have been numerous non-fatal attacks.
Fishing and bycatch
Spiny dogfish are frequent bycatch.[14] Great whites and porbeagles are protected, prohibiting targeted fishing
Research and conservation
AWSC and Massachusetts Division of Marine Fisheries have tagged over 250 great whites since 2009, tracking migrations to and from Cape Cod.[15] The Sharktivity app engages the public, with hundreds of thousands of users.[16] AWSC Shark Center in Chatham, opened in 2017, educates approximately 10,000 visitors annually to counter these misconceptions about sharks.[17]
Cultural impact
The 1975 film Jaws, filmed on Martha's Vineyard, significantly influenced public perceptions of sharks, often amplifying fear by portraying them as vengeful predators.[18]
Species
Several shark species inhabit or visit Cape Cod waters, with varying ecological roles and frequencies of sightings, among others:
- Great White Shark (Carcharodon carcharias): The most prominent species, great whites are apex predators feeding primarily on seals. Their population has increased since the 2000s due to seal population recovery under federal protection. Adults typically measure 11–16 feet and weigh up to 2,000 pounds.
- Basking Shark (Cetorhinus maximus): The second-largest fish species, these filter feeders consume plankton. They can grow up to 30 feet but pose no threat to humans.[19][20][21][22]
- Blue Shark (Prionace glauca): A slender, migratory species found in deeper offshore waters, blue sharks are less common near shore but frequent in the open Atlantic. They feed on squid and small fish.[23]
- Porbeagle Shark (Lamna nasus): Cold-water, year-round residents growing to 9.8 feet and 280 pounds, critically endangered[23][24]
- Spiny Dogfish (Squalus acanthias): A small, schooling shark (3–4 feet) abundant in Cape Cod waters, often caught by fishermen.[14] They feed on small fish and invertebrates.
- Shortfin Mako Shark (Isurus oxyrinchus): Aggressive predators reaching 13 feet, feeding on fish and marine mammals, living over 30 years.[23]
- Sand Tiger Shark (Carcharias taurus): Docile, growing to 10.5 feet and 350 pounds, recovering from overfishing due to protections.[23]
- Sandbar Shark (Carcharhinus plumbeus): Coastal sharks up to 8 feet, weighing 100–200 pounds, often in shallow waters.[25]
- Thresher Shark (Alopias spp.): Identified by long, sickle-shaped tails, growing to 20 feet, living ~20 years.
- Dusky Shark (Carcharhinus obscurus): Large, rare in New England[23]
- Tiger Shark (Galeocerdo cuvier): Known for dark juvenile stripes, growing to 14 feet and 1,400 pounds, second to great whites in human attacks.
- Whale Shark (Rhincodon typus): Largest fish, reaching 32.8 feet and 20.6 tons, docile plankton feeders, rarely near shore.[26]
- Hammerhead Shark (Sphyrna spp.): Distinctive hammer-shaped heads, growing to 20 feet and 1,000 pounds.[27]
Strandings on beaches
On February 5, 2025, a 26-foot female basking shark washed up dead on Wellfleet's Mayo Beach, the second such stranding in eight years. Experts found no trauma, with tissue samples under analysis. Cape Cod's coastline likely trapped the shark in the bay, a common issue for migrating marine animals. Basking sharks struggle to escape the bay's tides, often leading to fatal strandings.[22]
References
- ↑ "Cape Cod's Gray Seal and White Shark Problem Is Not Black-and-White". www.nrdc.org. 2018-11-09. Retrieved 2025-08-31.
- ↑ Fisheries, NOAA (2022-06-29). "Cape Cod Seals and Sharks: Shared Traits and Top 10 Facts | NOAA Fisheries". NOAA. Retrieved 2025-08-31.
- ↑ "Cape Cod Bay | Center for Coastal Studies". coastalstudies.org. Retrieved 2025-08-31.
- ↑ 4.0 4.1 "Great White Sharks In Cape Cod - Why Are Sharks Coming". 2022-05-05. Retrieved 2025-08-31.
- ↑ Rousseau, Morgan (2023-06-03). "Cape gets its first 'shark alert' of the 2023 season". Boston.com. Retrieved 2025-08-31.
- ↑ "New Study Reveals Dusky Sharks Preying on Seals for the First Time off the coast of Nantucket — AWSC". Atlantic White Shark Conservancy. 2025-08-27. Retrieved 2025-08-31.
- ↑ 7.0 7.1 "Atlantic White Shark Conservancy". Atlantic White Shark Conservancy. Retrieved 2025-08-31.
- ↑ Dedman, Simon; Moxley, Jerry H.; Papastamatiou, Yannis P.; Braccini, Matias; Caselle, Jennifer E.; Chapman, Demian D.; Cinner, Joshua Eli; Dillon, Erin M.; Dulvy, Nicholas K.; Dunn, Ruth Elizabeth; Espinoza, Mario; Harborne, Alastair R.; Harvey, Euan S.; Heupel, Michelle R.; Huveneers, Charlie (2024-08-02). "Ecological roles and importance of sharks in the Anthropocene Ocean". Science. 385 (6708): adl2362. Bibcode:2024Sci...385L2362D. doi:10.1126/science.adl2362. PMID 39088608 Check
|pmid=value (help). - ↑ Cristantiello, Ross (2024-05-23). "After recent signs of shark activity, officials issue warning ahead of holiday weekend". Boston.com. Retrieved 2025-08-31.
- ↑ "Cape Cod Bay sees 10 white shark sightings from the air in a single day". Yahoo News. 2025-08-01. Retrieved 2025-08-31.
- ↑ Kus, Mason (2025-04-14). "This U.S. Vacation Spot Has The Largest Concentration Of Great White Sharks, Study Revealed". TheTravel. Retrieved 2025-08-31.
- ↑ Sherman, Casey (2019-05-14). "The Shark Attack That Changed Cape Cod Forever". Boston Magazine. Retrieved 2025-08-31.
- ↑ Pinto, Luís M. "Shark kills 26-year-old bodyboarder in Cape Cod". Surfertoday. Retrieved 2025-08-31.
- ↑ 14.0 14.1 "Can dogfish save Cape Cod fisheries?". Christian Science Monitor. ISSN 0882-7729. Retrieved 2025-08-31.
- ↑ "Atlantic White Shark Conservancy Concludes Successful 2021 Research Season — AWSC". Atlantic White Shark Conservancy. 2021-12-27. Retrieved 2025-08-31.
- ↑ Styler, Jack (2024-07-10). "Inside Sharktivity". The Provincetown Independent. Retrieved 2025-08-31.
- ↑ Savio, Jason. "A fear of great whites? Shark center aims to show fact vs. fiction". Cape Cod Times. Retrieved 2025-08-31.
- ↑ "How Jaws misrepresented the great white". BBC News. 2015-06-08. Retrieved 2025-08-31.
- ↑ Skomal, Gregory B.; Zeeman, Stephen I.; Chisholm, John H.; Summers, Erin L.; Walsh, Harvey J.; McMahon, Kelton W.; Thorrold, Simon R. (2009). "Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean". Current Biology. 19 (12): 1019–1022. Bibcode:2009CBio...19.1019S. doi:10.1016/j.cub.2009.04.019. PMID 19427211. Unknown parameter
|s2cid=ignored (help) - ↑ "Giant Shark Mystery Solved: Unexpected Hideout Found". News.nationalgeographic.com. 28 October 2010. Archived from the original on 10 May 2009. Retrieved 15 August 2012. Unknown parameter
|url-status=ignored (help) - ↑ Thomas, Pete. "Enormous, rarely seen basking shark appears off Cape Cod; 'Holy cow, look at this!'". For The Win. Retrieved 2025-08-31.
- ↑ 22.0 22.1 McCarron, Heather. "Basking shark strands on Wellfleet beach: 2nd one in a decade". Cape Cod Times. Retrieved 2025-08-31.
- ↑ 23.0 23.1 23.2 23.3 23.4 Jacobson, Seth. "Great white sharks confirmed back off MA beaches. What other sharks are out there?". Cape Cod Times. Retrieved 2025-08-31.
- ↑ McCarron, Heather. "Is it legal to take teeth, fins from washashore porbeagle sharks? Here's what we know". Cape Cod Times. Retrieved 2025-08-31.
- ↑ Fisheries, NOAA (2025-05-13). "Sandbar Shark | NOAA Fisheries". NOAA. Retrieved 2025-08-31.
- ↑ "Watch as nearly 30-foot whale shark swims up to boat off Cape Cod". masslive. 2020-08-25. Retrieved 2025-08-31.
- ↑ "Thresher Shark On South Shore, Hammerhead On Cape". CapeCod.com. 2024-08-02. Retrieved 2025-08-31.
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