The rugged, rocky coastlines and chilly waters of Maine are home to some of the most charismatic marine mammals found in North America: seals.
These sleek, curious creatures are a common sight on Maine’s shores, islands, and in its harbors, and certainly no strangers to us here on the Blue Hill Peninsula. The seal population plays an important role in the coastal ecosystem and has become a symbol of the region’s rich marine biodiversity. It’s exactly why we assist on marine mammal rescues and also why we are studying the impact of PFAS chemicals on seals over the past 30 years, which is a study funded by a competitive grant that we won from NOAA. Click HERE to learn more about this study and why it matters.
So we thought we’d provide a short look at the different types of seals you can encounter off the coast of Maine, their habits, and where you’re most likely to spot them.
1. Harbor Seal (Phoca vitulina)
Harbor seals, also known as common seals, are the most frequently seen seal species in Maine. These seals have a rounded head with no external ear flaps, large expressive eyes, and a coat that ranges in color from silver-gray to brown, often spotted or mottled.
- Size: Adults average 5-6 feet in length and weigh between 180-285 pounds.
- Habitat: Harbor seals haul out on rocky ledges, sandbars, and remote beaches. They are particularly common around Mount Desert Island, Penobscot Bay, and Casco Bay.
- Behavior: These seals are often seen resting during low tide or swimming close to shore. They are shy and tend to slip into the water if approached too closely.
- Fun Fact: Harbor seals give birth to their pups in late spring to early summer. Pups can swim within hours of birth!
2. Gray Seal (Halichoerus grypus)
Gray seals are larger than harbor seals and have a more elongated snout, which gives them a “horse-headed” appearance. Their coat is darker, ranging from dark gray to brownish-black, with lighter blotches.
- Size: Males can reach up to 10 feet and weigh over 800 pounds, while females are smaller, averaging 6.5 feet and 400 pounds.
- Habitat: Once rare, gray seals have made a significant comeback in the Gulf of Maine. They are commonly found on remote islands, especially around Muskeget Island and the outer islands near Acadia National Park.
- Behavior: Gray seals are more social than harbor seals and can be seen in large groups, especially during the breeding season in winter.
- Fun Fact: Gray seal pups are born with a fluffy white coat and nurse for about 3 weeks, gaining up to 3 pounds per day.
3. Harp Seal (Pagophilus groenlandicus)
Harp seals are less common off Maine’s coast but occasionally make appearances, especially during winter months. They are known for their distinctive black “harp-shaped” markings on their backs.
- Size: Adults grow to about 5-6 feet long and weigh between 265-300 pounds.
- Habitat: Native to the Arctic and North Atlantic, harp seals sometimes migrate as far south as the Gulf of Maine.
- Behavior: These seals prefer pack ice but can be seen on open water or ice floes during their migration.
- Fun Fact: Harp seals have excellent vision underwater, helping them navigate the dark, icy waters of their northern habitat.
4. Hooded Seal (Cystophora cristata)
The hooded seal is a rare visitor to Maine’s waters, usually spotted only occasionally. Males are known for their inflatable nasal cavity, or “hood,” which they can blow up like a balloon.
- Size: Males can grow up to 8.5 feet long and weigh over 900 pounds; females are smaller.
- Habitat: Typically found in the North Atlantic, especially around Greenland and Iceland, some wander into Maine waters during their extensive migrations.
- Behavior: Solitary and elusive, hooded seals are deep divers and can stay submerged for over 30 minutes.
- Fun Fact: Hooded seal pups, called “bluebacks” due to their blue-gray fur, grow extremely quickly, weaning after just 4 days—the shortest lactation period among mammals.
Protecting Maine’s Seals
All seal species in U.S. waters are protected under the Marine Mammal Protection Act, which prohibits the harassment, hunting, capturing, or killing of marine mammals. As seal populations recover, especially gray seals, it’s essential for boaters, beachgoers, and wildlife watchers to respect their space. If you see a seal resting on a beach or rock, admire it from a distance—getting too close can stress the animal and may even be dangerous.
As mentioned above, we can help any seal that you believe could be in danger or under stress in the Blue Hill Peninsula coastal region. Please contact us directly if you believe you are seeing an animal in this situation. You can also contact us if you see a dead seal.
Best Places to Spot Seals in Maine
- Monhegan Island
- Boothbay Harbor
- Bar Harbor and Acadia National Park
- Seal Island National Wildlife Refuge
- Casco Bay Islands
- But truly, just keep your eyes open anywhere along the coast of Maine!
Guided boat tours often include seal watching as part of their experience, offering a great way to see these marine mammals in their natural habitat.
“Having only known West coast sea lions before moving up to Maine, getting to know seals on the east coast has been amazing,” said Dr. Charlie Rolsky, Executive Director of the Shaw Institute. “Not only are these animals critical to our ecosystems but they’re also top tiered predators that we consider to be sentinels or indicators of environmental health.”
Seals are a vital part of Maine’s marine ecosystem and a delight to observe in the wild. Whether you’re kayaking along the coast, hiking seaside cliffs, or taking a whale-watching cruise, keep an eye out for these graceful swimmers. Each species tells a story of adaptation and survival in the cold, nutrient-rich waters of the Gulf of Maine. And with continued conservation efforts, we can ensure that these marine icons remain a beloved part of Maine’s coastal heritage for generations to come.
Photo at top and gallery below courtesy of Karl Ramsdell
SEALS BY THE LENS OF KARL RAMSDELL
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