2 Types of Seals in Maine
Maine is home to three seal species: Harbor Seals, which are the most abundant year-round residents, Grey Seals, which have increased significantly in recent decades, and Harp Seals, which are rare winter visitors from the Arctic. Harbor Seals dominate Maine's waters with over 1,500 sightings, while Grey Seals account for around 600, and Harp Seals appear only occasionally during cold months. Knowing the differences helps you identify which species you are seeing on the water or on coastal rocks.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated July 2, 2026.
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- species recorded
- July, June, August
- peak months
Verified species, source iNaturalist
2 types of seals recorded in Maine
2 seal species have a verified observation record in Maine, each with at least 10 confirmed sightings. The full list, ranked by how often each is recorded, is below.
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Plus 1 more recorded only rarely (fewer than 10 verified sightings). Counts from verified iNaturalist observations. Photos by iNaturalist observers, reused under the licence each observer chose.
More on seals in Maine:
Real sighting data, source iNaturalist
2,276 verified observations on iNaturalist of seal have been recorded in Maine, most often in July, June, August.
When seal are recorded in Maine
Maine is home to three seal species: Harbor Seals, which are the most abundant year-round residents, Grey Seals, which have increased significantly in recent decades, and Harp Seals, which are rare winter visitors from the Arctic. Harbor Seals dominate Maine's waters with over 1,500 sightings, while Grey Seals account for around 600, and Harp Seals appear only occasionally during cold months. Knowing the differences helps you identify which species you are seeing on the water or on coastal rocks.
What is the most common seal in Maine?
Harbor Seals are by far the most abundant seal species in Maine, with more than 1,500 documented sightings on iNaturalist. These seals range from 5 to 6 feet long and weigh 100 to 250 pounds. Their coloring varies from gray to brown or spotted patterns. Harbor Seals are present year-round, though sightings peak in summer months from June through August when they haul out on rocks and reefs to rest. They prefer rocky coastal areas and estuaries where they can access both the ocean and freshwater feeds.
How do you tell a Harbor Seal from a Grey Seal?
The easiest way to distinguish these two species is size and head shape. Harbor Seals are smaller, typically 5 to 6 feet long, with a rounded head that looks almost cat-like when viewed head-on. Their nostrils are V-shaped and close inward. Grey Seals are larger, reaching 6.5 to 8 feet or more, with a longer, more rectangular face and a prominent nose. Their nostrils are more parallel and open outward. Coloring alone is not reliable, as both species can be gray, brown, or spotted. On the water, observe the head profile: if it looks small and rounded, it is a Harbor Seal. If it looks long and stout, it is likely a Grey Seal.
Grey Seal numbers and range in Maine
Grey Seals have become increasingly common in Maine waters over the past 30 years. iNaturalist records show around 600 sightings, making them the second most documented seal species in the state. Adults typically weigh 250 to 700 pounds, with males considerably larger than females. Grey Seals are found throughout Maine's coastal zone but are more prevalent in the colder, deeper waters of the Gulf of Maine. Summer sightings spike from June through August, coinciding with their haul-out season. Their expansion reflects broader Atlantic population recovery following historical overhunting.
Are Harp Seals present in Maine?
Harp Seals are rare in Maine and appear only as occasional winter visitors from the Arctic. iNaturalist records just 9 sightings, typically occurring between December and March. These seals are smaller than Harbor Seals, weighing 150 to 400 pounds, and are recognizable by their distinctive black harp-shaped or saddle-shaped markings on their silvery-gray backs and white bellies. When they do occur in Maine, they are usually found in the Gulf of Maine or off the coast during ice-on periods in their breeding range. Most Harp Seal sightings in Maine occur in late winter when Arctic ice retreats and young or weaned seals drift southward.
What distinguishes Harp Seals from the other two species?
Harp Seals are unmistakable if you see one clearly. They are smaller than Grey Seals and have fine, elegant features compared to the blockier heads of Harbor and Grey Seals. The harp-shaped black or dark marking on the back is unique to Harp Seals and immediately confirms identification. Their coat is generally lighter and more silvery than Harbor or Grey Seals. Harp Seals also have a sleeker profile in the water. In Maine, seeing a Harp Seal is rare enough that any clear sighting should be documented and reported to state wildlife authorities.
Which seal species is best to see in Maine during summer?
Harbor Seals are your best bet for a summer seal encounter in Maine. They haul out on coastal rocks in June, July, and August and are the most commonly observed in these months. They tend to be more tolerant of boats and observers when resting on rocks compared to Grey Seals, though keeping a respectful distance is still essential. Popular places like Acadia National Park, Boothbay Harbor, and Bar Harbor offer regular sightings of Harbor Seals during these peak months. Grey Seals are also present in summer but are somewhat more elusive and less predictable in their hauling behavior.
Do seals breed in Maine?
Both Harbor Seals and Grey Seals breed in Maine, though at different times and in different numbers. Harbor Seals typically breed from May through June, giving birth to pups that are already able to swim. Grey Seal breeding occurs in the fall and winter, roughly from September through February. The peak pupping season for Grey Seals is December through January. Harp Seals breed in the Arctic and do not breed in Maine. The breeding seasons of Harbor and Grey Seals can affect where and when you are likely to find them, with females becoming more protective and defensive during these periods.
What habitats do Maine seals prefer?
All three seal species in Maine favor rocky coastal areas, islands, and offshore reefs for hauling out. Harbor Seals prefer calmer, shallower coastal waters and will haul out on nearly any rocky surface from public rocks to private jetties. Grey Seals are comfortable in rougher, deeper waters and tend to haul out on more exposed rocks and ledges. Both species will use rocky areas near estuaries where freshwater and saltwater meet. In Maine, the rocky coasts from Acadia National Park south through Boothbay Harbor and into Cape Cod provide ideal habitat. Harp Seals, when present, stick to deeper Gulf of Maine waters and are not typically observed on haul-out sites like the other two species.
Can you hear seals in Maine?
Maine seals are generally quiet on land, though they do vocalize underwater and occasionally make grunting or snorting sounds when hauled out. Harbor Seals produce a variety of calls, including growls, snorts, and barks, especially when alarmed or defending space. Grey Seals also grunt and growl and are sometimes observed bellowing at other seals. These sounds are more pronounced during breeding season. Underwater, all three species produce clicks, whistles, and other vocalizations used for communication and navigation. If you are on a boat or shore near a seal haul-out and hear unexpected animal sounds, seals could well be the source.
How do seal populations in Maine compare to the past?
Maine's seal populations have changed dramatically over the past century. Historic overhunting reduced both Harbor and Grey Seals to near extinction by the early 1900s. Legal protections enacted in the 1970s have allowed both species to recover. Harbor Seal populations are now stable at healthy levels, and Grey Seals have expanded their range and abundance far beyond historical norms. This recovery is considered a conservation success but has raised questions about predation on fish stocks and interactions with fisheries. Harp Seal numbers in Maine remain low and sporadic, driven by Arctic ice conditions and food availability in northern waters.
Frequently asked questions
What types of seals live in Maine?+
Harbor Seals are by far the most abundant seal species in Maine, with more than 1,500 documented sightings on iNaturalist. These seals range from 5 to 6 feet long and weigh 100 to 250 pounds. Their coloring varies from gray to brown or spotted patterns. Harbor Seals are present year-round, though sightings peak in summer months from June through August when they haul out on rocks and reefs to rest. They prefer rocky coastal areas and estuaries where they can access both the ocean and freshwater feeds.
How do you tell seals apart in Maine?+
Harbor Seals are by far the most abundant seal species in Maine, with more than 1,500 documented sightings on iNaturalist. These seals range from 5 to 6 feet long and weigh 100 to 250 pounds. Their coloring varies from gray to brown or spotted patterns. Harbor Seals are present year-round, though sightings peak in summer months from June through August when they haul out on rocks and reefs to rest. They prefer rocky coastal areas and estuaries where they can access both the ocean and freshwater feeds.
Which seal is most common in Maine?+
Harbor Seals are by far the most abundant seal species in Maine, with more than 1,500 documented sightings on iNaturalist. These seals range from 5 to 6 feet long and weigh 100 to 250 pounds. Their coloring varies from gray to brown or spotted patterns. Harbor Seals are present year-round, though sightings peak in summer months from June through August when they haul out on rocks and reefs to rest. They prefer rocky coastal areas and estuaries where they can access both the ocean and freshwater feeds.
Keep exploring
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Common questions about seals