How to Identify Seal in New Jersey

Harbor Seals are the most frequently sighted seal in New Jersey, accounting for the majority of observations. They measure 4 to 6 feet long and have a distinctly dog-like face with a V-shaped nostrils and no ear flaps. Their coat is gray, brown, or tan with irregular dark spots or rings. Harbor Seals have a robust body and tend to rest on beaches, rocks, and jetties with their rear flippers trailing behind. They are generally smaller and more slender than Grey Seals, and their heads are more rounded.

Grey Seals are larger and bulkier than Harbor Seals, reaching 6 to 8 feet in length. Males are darker and bulkier; females are often lighter. The most distinctive feature is their head shape, which is longer and more horse-like with a straight profile from forehead to nose, giving them a pronounced snout. Their nostrils are more parallel and set further apart than a Harbor Seal. Grey Seals often display more uniform coloring compared to Harbor Seals, though they can still have spots. They appear in New Jersey observations with much lower frequency than Harbor Seals.

Harp Seals are less common in New Jersey than Harbor or Grey Seals, with only 18 sightings on record. They are medium-sized at 5 to 6 feet long. Harp Seals have a smoother, more refined face than Harbor Seals and a gray coat. Juveniles lack the distinctive dark harp-shaped or saddle marking on their back that gives adults their name, but even young Harp Seals have a more elegant profile than stocky Harbor Seals. If you observe a seal in New Jersey that seems unusually pale or refined compared to the more common Harbor Seal, it may be a Harp Seal.

The Hooded Seal is extremely rare in New Jersey, with only one iNaturalist record. Hooded Seals are large animals, up to 8 feet long, and males have an expandable hood of skin on their head that they can inflate. If you spot a Hooded Seal, it would be a significant sighting for the state and worth documenting with a photograph and location details.

Seal nostrils are a quick way to distinguish species. Harbor Seals have V-shaped nostrils that point downward like an upside-down V. Grey Seals have more parallel, slit-like nostrils that sit further apart and point slightly outward. Both sets of nostrils are on the snout's top surface. From a distance this is hard to see, but if you have binoculars or a clear view of a hauled-out seal, the nostril shape and spacing provide reliable identification clues.

Seals lack external ear flaps, or pinnae, which is one way to tell them apart from sea lions. Instead, seals have ear holes that are flush with their head. If you see a marine mammal with visible ear flaps on the sides of its head, it is a sea lion, not a seal. New Jersey seals all lack these external ear flaps.

Harbor Seals typically show irregular dark spots or rings on a gray, tan, or brown base. Grey Seals tend to have more uniform coloring, though they can also display spotting. Harp Seals have a gray coat and may show faint markings. Variation exists within each species, and juveniles sometimes look quite different from adults, so color alone is not a reliable identifier. Head shape, body size, and nostril structure are more dependable field marks.

Size is a useful supporting clue. Harbor Seals are typically the smallest at 4 to 6 feet long. Harp Seals are slightly larger and more refined, at 5 to 6 feet. Grey Seals are the largest and most robust, reaching 6 to 8 feet, with males noticeably bigger and bulkier than females. If you observe a very large, heavy-bodied seal, Grey Seal is the most likely identification. A smaller, more delicate seal is more likely a Harbor Seal or Harp Seal.

From a distance, focus on head shape and body proportions. A long, horse-like head with a straight profile points to Grey Seal. A rounder, more dog-like face suggests Harbor Seal. Use the trunk page to understand when and where each species is most common so you can apply what you observe to the season and location. Peak months for seals in New Jersey are January, February, and March, when all species are more likely to haul out on beaches and visible areas.

For detailed field guides and additional photographs, visit the /wildlife/new-jersey/seal page for habitat and seasonal information. The iNaturalist platform also hosts thousands of seal photographs with species identification and geographic data that can help you refine your eye. Local New Jersey wildlife guides and university extension programs often provide seal identification workshops and resources.