Maine’s coastal waters might surprise you with their shark diversity. While many people assume these cold Atlantic waters are shark-free, you could actually encounter up to 10 different shark species during your summer swim.
Most pose no threat to humans, but knowing which sharks inhabit Maine waters and how to respond safely can make your ocean experience both informed and enjoyable.
The Gulf of Maine serves as a seasonal home and migration route for various shark species, from massive filter-feeders to swift predators.
Understanding these marine predators helps you appreciate Maine’s rich ecosystem while staying prepared for potential encounters.
Types of Sharks in Maine
Porbeagle Shark
The porbeagle shark (Lamna nasus) represents one of Maine’s most common shark residents during warmer months. These robust sharks typically measure 6-8 feet in length and possess a distinctive white patch at the base of their dorsal fin. You’ll recognize them by their torpedo-shaped body and prominent triangular dorsal fin.
Porbeagles prefer cooler waters, making Maine’s coastal areas ideal habitat from late spring through early fall. They primarily hunt mackerel, herring, and other schooling fish near the surface, occasionally coming close to shore while following prey.
Pro Tip: Porbeagles are curious but generally avoid humans. If you spot one, remain calm and slowly back away while maintaining eye contact.
These sharks pose minimal risk to swimmers, with no recorded attacks on humans in Maine waters. Their diet consists almost exclusively of fish, and they typically avoid areas with heavy human activity. Research from NOAA Fisheries indicates porbeagles are more afraid of humans than we are of them.
Shortfin Mako Shark
Shortfin mako sharks (Isurus oxyrinchus) earn recognition as the ocean’s fastest sharks, capable of reaching speeds up to 45 mph. These sleek predators typically measure 8-12 feet and display a brilliant blue coloration on their backs with white undersides. Their pointed snouts and large eyes make them easily identifiable.
Maine waters attract makos during summer months when they follow warm currents northward. They prefer deeper offshore waters but occasionally venture into shallower areas while pursuing fast-moving prey like tuna and swordfish.
Characteristic | Shortfin Mako | Porbeagle |
|---|---|---|
Speed | 45 mph | 25 mph |
Size | 8-12 feet | 6-8 feet |
Habitat | Offshore | Coastal |
Risk Level | Moderate | Low |
While mako attacks on humans remain rare, their speed and size warrant respect. If you encounter a mako, avoid sudden movements and slowly exit the water. These sharks respond to erratic behavior as potential prey signals.
Blue Shark
Blue sharks (Prionace glauca) showcase stunning indigo coloration that makes them among the most beautiful sharks in Maine waters. These slender sharks typically reach 6-10 feet in length and possess distinctively long pectoral fins that resemble wings.
These highly migratory sharks travel thousands of miles annually, with Maine serving as a summer feeding ground. Blue sharks prefer open ocean environments but sometimes approach coastal areas while following schools of squid and small fish. They’re particularly active during dawn and dusk hours.
Important Note: Blue sharks are naturally curious and may approach swimmers, but they’re generally not aggressive toward humans.
According to Florida Museum research, blue sharks account for very few unprovoked attacks worldwide. Their diet consists primarily of squid, small schooling fish, and occasional seabirds. Most interactions with humans result from the shark’s curiosity rather than predatory behavior.
Great White Shark
Great white sharks (Carcharodon carcharias) generate the most concern among Maine swimmers, though encounters remain extremely rare. These apex predators can reach lengths of 15-20 feet and display the classic white underside with gray upper coloration. Their triangular, serrated teeth and robust build make them unmistakable.
Maine’s waters serve as a nursery area for juvenile great whites, typically measuring 6-10 feet. Adult great whites visit seasonally, following seal populations along the coast. The presence of these magnificent predators indicates a healthy marine ecosystem.
- Stay calm and maintain eye contact if you spot one
- Back away slowly without turning your back
- Avoid areas with high seal activity
- Don’t swim alone in areas with known great white activity
- Exit the water calmly if advised by lifeguards
Great white attacks in Maine waters remain extraordinarily rare, with most incidents involving cases of mistaken identity. These sharks primarily target seals and large fish, showing little interest in humans as prey.
Thresher Shark
Thresher sharks (Alopias vulpinus) stand out due to their extraordinarily long tail fins, which can equal their body length. These unique sharks typically measure 10-14 feet total length, with nearly half consisting of their distinctive tail. They use this appendage like a whip to stun schools of fish.
Maine waters attract threshers during summer months when they follow schools of mackerel, herring, and bluefish. They prefer deeper waters but occasionally venture into shallower areas while hunting. Their hunting technique involves using their tail to create stunning water strikes.
Key Insight: Thresher sharks are completely harmless to humans, focusing exclusively on small schooling fish with their specialized hunting technique.
These gentle giants pose zero threat to swimmers, with no recorded attacks on humans anywhere in the world. Their small mouths and fish-focused diet make them one of the safest large sharks to encounter. Threshers typically flee when they detect human presence.
Basking Shark
Basking sharks (Cetorhinus maximus) rank as the second-largest fish in the world, reaching lengths up to 40 feet. Despite their massive size, these gentle giants feed exclusively on plankton, small fish, and crustaceans through filter feeding. Their enormous mouths can open up to 3 feet wide.
These magnificent creatures visit Maine waters during summer months, often seen swimming slowly at the surface with their dorsal fins exposed.
They follow plankton blooms and can appear in large groups, creating spectacular wildlife viewing opportunities for New England marine enthusiasts.
Basking sharks present absolutely no danger to humans and often allow close observation. Their docile nature and filter-feeding behavior make them popular with wildlife watchers.
However, their massive size requires respectful distance to avoid accidental contact with their powerful tail.
Species | Size | Diet | Danger Level |
|---|---|---|---|
Basking Shark | Up to 40 feet | Plankton | None |
Great White | 15-20 feet | Seals, large fish | Very Low |
Thresher | 10-14 feet | Small schooling fish | None |
Smooth Dogfish
Smooth dogfish (Mustelus canis) represent Maine’s most common small shark species, typically measuring 2-4 feet in length.
These slender sharks display gray-brown coloration with a smooth skin texture that gives them their name. Their small size and docile nature make them popular subjects for marine research.
These abundant sharks inhabit coastal waters year-round, preferring sandy and muddy bottoms where they hunt crabs, worms, and small fish. Smooth dogfish often form large schools and frequently venture into very shallow water, including tidal pools and estuaries.
Encounters with smooth dogfish pose no threat to humans. Their small mouths and bottom-feeding behavior focus on invertebrates rather than large prey. Many swimmers never realize they’ve shared the water with these harmless sharks, as they typically avoid human activity.
Spiny Dogfish
Spiny dogfish (Squalus acanthias) earn their name from the sharp spines located in front of each dorsal fin. These small sharks typically measure 2-3 feet and display gray coloration with white spots along their sides. They’re among the most abundant sharks in Maine waters.
These hardy sharks tolerate a wide range of temperatures and can be found in Maine waters year-round, though they’re most active during cooler months. They form massive schools that can contain thousands of individuals, creating impressive underwater spectacles.
Common Mistake: Don’t attempt to handle spiny dogfish if you encounter one while swimming. Their defensive spines can cause painful wounds.
While spiny dogfish don’t pose a bite threat to humans, their defensive spines can inflict painful wounds if handled improperly. These sharks typically avoid swimmers and divers, preferring to feed on small fish, squid, and crustaceans in deeper waters.
Greenland Shark
Greenland sharks (Somniosus microcephalus) represent one of nature’s most remarkable species, potentially living over 400 years. These massive sharks can reach 20 feet in length and inhabit the deepest, coldest waters off Maine’s coast. Their slow-moving nature and deep-water habitat make encounters extremely rare.
These ancient predators prefer waters below 40°F and typically inhabit depths exceeding 600 feet. They occasionally venture into shallower waters during winter months but rarely interact with human activities. Their diet includes fish, seals, and even polar bears in their Arctic range.
Greenland sharks pose virtually no threat to Maine swimmers due to their deep-water habitat and sluggish movement. Most Maine residents will never encounter one, as they prefer the frigid depths far from popular swimming areas. Research from Science Magazine reveals these sharks as among Earth’s longest-living vertebrates.
Sixgill Shark
Sixgill sharks (Hexanchus griseus) represent living fossils, having remained virtually unchanged for 200 million years. These primitive sharks can reach impressive lengths of 15-20 feet and possess six gill slits instead of the typical five found in modern sharks. Their broad heads and powerful builds reflect their ancient lineage.
These deep-water specialists inhabit Maine’s continental shelf and slope waters, typically at depths exceeding 300 feet. They occasionally venture into shallower waters at night while hunting, but daytime encounters near shore remain virtually impossible.
Sixgill sharks present no realistic threat to Maine swimmers due to their deep-water preferences and nocturnal hunting behavior. Their diet consists of fish, squid, crabs, and even other sharks. These magnificent creatures prefer the mysterious depths where few humans venture, making them more legend than reality for most coastal visitors.
Pro Tip: If you’re interested in Maine’s diverse marine life, consider visiting during different seasons when various species are most active.
What to Do During Shark Encounters
Understanding proper response protocols can transform a potentially frightening encounter into a memorable wildlife experience.
Most shark encounters in Maine waters involve harmless species, but following established safety guidelines ensures positive outcomes for both you and the shark.
The key to safe shark encounters lies in remaining calm and avoiding actions that might trigger defensive or investigative behavior. Sharks respond to movement patterns, electrical signals, and vibrations in ways that can either escalate or defuse situations.
Immediate Response Actions
- Remain calm and avoid sudden movements that might attract attention
- Maintain eye contact with the shark while slowly backing toward shore
- Keep your movements smooth and deliberate rather than panicked
- Position yourself vertically in the water to appear larger
- Back away slowly while facing the shark until you can safely exit
Never turn your back on a shark or attempt to swim away rapidly, as this can trigger chase responses in some species. Most sharks in shallow areas are simply passing through or investigating, not hunting.
Prevention Strategies
Avoiding shark encounters altogether represents the safest approach for Maine swimmers. Understanding shark behavior patterns and environmental factors helps you make informed decisions about when and where to swim.
- Avoid swimming during dawn and dusk when many shark species are most active
- Stay away from areas with visible seal populations or fishing activity
- Don’t swim alone, especially in deeper waters or areas with limited visibility
- Avoid wearing shiny jewelry that might resemble fish scales
- Exit the water if you notice unusual fish behavior or bird activity
Pay attention to local conditions and advisories from marine authorities. Areas with recent shark sightings or unusual marine mammal activity warrant extra caution. Many Maine beaches provide current information about marine conditions and wildlife activity.
Understanding Shark Behavior
Most shark species in Maine waters show little interest in humans and actively avoid contact when possible. Understanding their natural behaviors helps distinguish between normal activity and potentially concerning situations.
Key Insight: Sharks are naturally curious animals, and most “aggressive” behavior actually represents investigation rather than predatory intent.
Investigative behavior includes circling, approaching slowly, or bumping with their snouts. This behavior typically occurs when sharks encounter unfamiliar objects or situations. Predatory behavior, which is extremely rare toward humans, involves rapid approaches, aggressive movements, or persistent following.
Remember that Maine’s shark populations play crucial roles in maintaining healthy marine ecosystems. These apex predators help control fish populations and maintain the balance that supports the state’s thriving fishing industry and marine tourism.
Your chances of encountering any shark while swimming in Maine remain remarkably low, with most species preferring deeper waters or specific hunting grounds away from popular beaches.
By understanding these magnificent creatures and following basic safety guidelines, you can enjoy Maine’s beautiful coastal waters with confidence and respect for the diverse marine life that calls these waters home.
