Types of Seal in New Hampshire

Harbor Seals dominate the state's seal population. They account for 54 of the 69 recorded sightings on iNaturalist, making them far more likely than Grey or Harp seals. Harbor Seals are mid-sized, typically 5 to 6 feet long, with a compact, stocky build. They range in color from tan or silver to brown or spotted gray, and their head is rounded with forward-facing nostrils arranged in a V-shape. You'll find them hauled out on rocky ledges, sandbars, and coastal islands, especially in the Great Bay and along the Atlantic coast.

Grey Seals are larger than Harbor Seals, reaching 6 to 7 feet in length, with a more elongated snout and a longer, flatter profile. They tend toward silvery gray, light gray, or darker charcoal coloring, sometimes with lighter spots or bands. The most reliable field mark is the head profile: a Grey Seal has a long, straight snout that juts forward, whereas a Harbor Seal's muzzle is rounder. Grey Seals are less common in New Hampshire, with 9 recorded sightings, and they favor rocky offshore areas and kelp zones. Winter is the most likely season to encounter one.

Harp Seals are the rarest of the three, with only 3 recorded sightings. They migrate from Arctic breeding grounds and do not establish year-round populations in New Hampshire. When they do appear, it is almost always during late autumn or winter, when ice retreat forces them southward. Harp Seals are slender and medium-sized, about 5 to 6 feet long, and adults often show distinctive dark-colored heads with silvery bodies. Juveniles are white or pale, which is why they sometimes attract attention on beaches. Spotting one in New Hampshire is a rare event.

February, January, and May are the months with the most seal sightings. January and February coincide with winter hauling-out season when seals congregate on predictable sites for rest and thermoregulation. May shows elevated counts, possibly due to increased survey effort and seasonal movement patterns. December and November also record reasonable numbers. Late summer and autumn (September, October) see fewer sightings. April and June-July have the lowest counts, suggesting seals disperse or move away during the warmer months.

Size is useful but not always reliable without a clear reference. Harbor Seals average 5 to 6 feet, Grey Seals reach 6 to 7 feet or more, and Harp Seals are 5 to 6 feet, overlapping significantly. A young Grey Seal can resemble a large Harbor Seal. The head shape, snout profile, and facial proportions are more dependable identifiers. At a distance or when the animal is in water, coloration and fur pattern can also help. Combine size with head profile, nostril shape, and context (location, season, hauling habit) for confident identification.

Rocky ledges, small offshore islands, and sandbars are preferred haul-out sites. The Great Bay, particularly around Isles of Shoals and coastal rocky areas, hosts the largest concentrations. Salt marshes and estuaries also attract seals, especially during high tide. Seals seek locations that offer safety from predators, access to deep water for escape, and visibility for spotting threats. Public beaches and busy harbors support fewer seals because human activity forces them to more remote sites. The seals that do appear in accessible areas are often young or exploratory individuals.

Seals make a variety of sounds both underwater and above water. Hauled-out seals produce grunts, barks, and occasional roars, especially when stressed or interacting with one another. These vocalizations are typically low-frequency and can carry surprising distances. Underwater, seals emit clicks, whistles, and chirps for communication and echolocation. The sounds are rarely loud enough to hear from shore during casual viewing, but if you approach a haul-out, you may hear warning barks or territorial displays. Audio identification is not practical for most observers.

Calm seas and clear visibility favor seal spotting. High winds and rough water push seals into deeper offshore zones and make them harder to observe. Fog and low light reduce your ability to see and identify seals. Tide cycles also matter: seals typically haul out during mid to high tide when sandbars and rocks are accessible. Sunny days encourage seals to rest ashore for thermoregulation, whereas stormy days send them to deeper water. Early morning and late afternoon offer the best light for spotting and photography. Checking weather and tide forecasts before a seal-viewing trip significantly improves your odds.

Yes. Federal law protects all marine mammals in United States waters, including seals, under the Marine Mammal Protection Act. It is illegal to hunt, harm, or harass seals in New Hampshire. State and federal agencies monitor seal populations and enforce these protections. Violations carry substantial fines and potential imprisonment. This legal protection has allowed seal populations to recover in recent decades. You may view and photograph seals from a distance, but you must never approach, touch, or pursue them. If you encounter a seal on a beach or in distress, contact a local marine wildlife agency rather than attempting to help directly.

Seals have nostrils that open and close but no external ear flaps; their ears are just holes in their head. Sea lions, by contrast, have prominent external ear pinnae, a difference that makes identification straightforward at a glance. New Hampshire has no native sea lions, so this distinction is mainly educational. All three seal species found in New Hampshire have the closed-nostril, no-external-ear design. When you see a seal hauled out in New Hampshire, you will notice the lack of ear flaps immediately once you know what to look for.