Raising its head just above the water’s surface, the harbor seal reveals its cute smiling face, a small snout and puppy-like eyes. Resubmerging, the seal swims off gracefully, flipping its pair of hind flippers from side to side while using its fore-flippers (front) to set its course. Adults can swim as fast as 12 mph over a short distance and dive to depths of about 1,500 feet, remaining submerged for 15 to 25 or more minutes. Not equipped with feet, harbor seals are not quite so nimble when they haul out onto an isolated beach, sand bar, rock or a drifting glacier. Out of the water, they move along by bouncing up and down in a caterpillar-like motion. They then lie down in what is described as a “banana” position, with their hind legs and head raised in the air.
Harbor seals routinely haul out for hours at a time, remaining by themselves or in loosely formed groups. It is believed that they may do so to rest, regulate their body temperature and avoid ocean predators. While hauled out, they remain alert and if threatened, they head back into the water.
Aggression between adults can be met with a growl, snort, a wave of their fore-flipper or thrust of their head back and forth toward the intruder. However, fighting among harbor seals is relatively rare except between competing males during the reproductive season.
Each year, from mid to late summer, the seals head out of the water to molt, shedding their hair and growing a new coat. During the process which can last one to two months, they spend most of their time onshore. Females generally molt right after their newborn pups are weaned.
Harbor seals can weigh up to 285 pounds and grow to a length of 5 to 6 feet. Males are slightly larger than females. The seals reach sexual maturity between the ages of 3 to 7 years and have a lifespan of 25 to 30 years. They can sleep underwater for up to 30 minutes!
Each year, the seals tend to return to the same breeding grounds. Mating generally takes place in shallow water, during the spring through early fall. Females carry their developing offspring for ten months and give birth at a haul-out site. They then nurse their newborn with fat-rich milk for about 4 to 6 weeks. The pups weigh about 24 pounds at birth and surprisingly they are born with a natural ability to swim! When just 2 to 3 days old, they can submerge for up to 2 minutes. Like their parents, the pups have well-developed eyes, that allow them to easily follow their mothers in the water, chasing her and sometimes riding on her back. Harbor seal’s eyes are equipped with round lenses and an iris that opens wide underwater. During haul-outs, their pupil closes down to accommodate the brighter light. In deep water, photoreceptor cells enhance their vision. In very murky water, they use their highly sensitive whiskers to detect flow patterns, allowing them to track swimming prey and predators. In 2001, the University of Bonn, Germany, demonstrated that blindfolded harbor seals could tract robotic fish by simply using their whiskers.
Their prey consists of fish, squid, mollusks and crustaceans. After weaning, pups first feed on shrimps and small bottom-dwelling crabs. The seal’s ocean predators consist mainly of sharks and killer whales. In Alaska waters, they also serve as prey for sea lions and polar bears.
These seals are not equipped with ear flaps. Instead, they have small openings on either side of their head that close when they dive. Their hearing underwater is excellent. Using grunts, growls and other sounds, males defend their underwater territory and work to attract a female during mating season. On the surface, they use sounds for the same purpose. Overall, however, they are the least vocal of all other pinnipeds (seals, sea lions, and walruses). Pups produce a call that is easily recognized by their mothers. Their moms also use their sense of smell to find their pup on a crowded breeding beach.
The five subspecies of harbor seals range from (1) the northern European waters and Iceland, (2) Greenland, the eastern Canadian Arctic to the mid-Atlantic. In the (3) Pacific, they range from Alaska to Baja, California and (4) a chain of Russian and Japanese islands. The last of the harbor seals subspecies (5), called Ungava seals, is the only species known to live in freshwater year-round. They inhabit freshwater lakes and rivers in northern Quebec that drain into the Hudson and James Bays.
These fascinating marine animals migrate from the Atlantic Provinces of Canada and Maine to our shores during the colder winter months. They sometimes arrive in Rhode Island’s Narragansett Bay as early as late October, remaining there until early April. In 2016, the state’s governor designated harbor seals as the State’s official marine mammal. In Long Island Sound, they make it into its waters by December and usually return to their home grounds in March.
In the Connecticut River, the harbor seals often swim up into its freshwater, following a shad run. On the Hudson River, a juvenile harbor seal was spotted more than 100 miles upriver. It then took up residence just off the Saugerties Lighthouse for nearly two years. Harbor seals can also be spotted in Chesapeake Bay and on rare occasions, on North Carolina’s Outer Banks.
In many areas along our coast, these puppy-like creatures are an active tourist attraction. The best time to see them at one of their haul-out sites is during a low tide, on a calm day. From land, it is recommended that you maintain a 300-foot distance, viewing them with binoculars and photographing them with a 300 to 500-mm camera lens. From a boat, run it slowly and parallel to the site, avoiding a direct approach that can easily spook them. The 1972 Marine Mammal Protection Act prohibits hunting, capturing, disturbing or harassing seals or any other marine mammal.
However, there are some great opportunities to enjoy harbor seals close-up. They are part of the exhibits at Connecticut’s Maritime Aquarium-Norwalk and Mystic Aquarium and New York Aquarium, Brooklyn, New York.