Sharks are present in Cape Cod waters, forming a natural part of the marine ecosystem. Their presence has become more notable in recent years, particularly during the warmer months, prompting a greater focus on understanding their behavior and ensuring public safety.
Sharks of Cape Cod
The waters surrounding Cape Cod are home to various shark species, with the great white shark (Carcharodon carcharias) being the most prominent. These apex predators can grow to impressive sizes, reaching up to 19.1 feet in length and weighing around 4,400 pounds. While great white sharks are the primary species of concern for beachgoers, other sharks like dogfish, thresher sharks, sand tiger sharks, and basking sharks also inhabit these coastal areas. The porbeagle shark is one of the few species that may reside in Cape Cod waters year-round.
Why Sharks are Drawn to Cape Cod
The increased presence of great white sharks in Cape Cod waters is directly linked to the thriving seal population, their primary food source. Historically, seal populations were severely depleted due to hunting. The Marine Mammal Protection Act in 1972 led to a significant rebound in gray and harbor seal numbers, now estimated at 30,000 to 50,000 individuals in southeastern Massachusetts. This resurgence provides an abundant food supply, drawing great white sharks to areas where seal colonies congregate. The return of these sharks represents a successful ecological recovery, restoring a natural predator-prey balance.
Understanding Shark Encounters
Shark activity on Cape Cod is seasonal, typically from May or June through October or November, with peak presence in late summer and early fall when ocean temperatures are warmest. Great white sharks are most frequently sighted along the Outer Cape beaches, stretching from Monomoy Island in Chatham northwards through Orleans, Eastham, Wellfleet, Truro, and Provincetown. These areas often have higher concentrations of seals, which attract sharks closer to shore. Research indicates sharks spend approximately 47% of their time in waters 15 feet deep or less, making them potentially closer to recreational areas.
Despite increased sightings, human-shark interactions remain rare. Since 2012, there have been three recorded shark bites off Truro and Wellfleet, including one fatality in 2018. The likelihood of a fatal shark attack is considerably lower than other common beach hazards, such as drowning or rip currents. Encounters often occur when sharks mistake humans for their natural prey, such as seals, particularly in areas with poor visibility or near seal activity.
Safety on Cape Cod Beaches
Visitors to Cape Cod beaches can take several steps to minimize risks and ensure a safe experience. Swim only in designated areas with lifeguards and stay close to the shore, making it easier for rescuers to respond. Avoiding isolated swimming and opting to swim, paddle, or surf in groups can also enhance safety.
Awareness of surroundings is important. Avoid areas where seals are present, as these are foraging grounds for sharks. Swimmers should also steer clear of murky or low-visibility waters and areas where schools of fish are visible, as these conditions can attract sharks. Limiting excessive splashing and refraining from wearing shiny jewelry can help prevent inadvertently attracting a shark’s attention, as these might be mistaken for fish scales.
Local authorities and organizations like the Atlantic White Shark Conservancy (AWSC) actively monitor shark activity and provide public safety information. Beachgoers should pay attention to local advisories, flag systems, and lifeguard instructions. A purple flag often indicates a shark sighting, while a red flag signifies unsafe swimming conditions. Utilizing the Sharktivity App, developed by AWSC, allows individuals to track real-time shark sightings and report new observations, contributing to collective awareness. If a shark is sighted, promptly notifying a lifeguard will lead to temporary water closures to ensure public safety.