As the sun begins to set for the summer, the Delaware beaches begin to attract a different group of visitors arriving from all over the East Coast. They are especially fond of local seafood, enjoy long afternoons on the beach, and frequent frolics in the ocean. But they typically don’t require a rental or transportation. They can be loud if their beach naps are disturbed, but they will generally keep to themselves.
We are speaking about the four species of seals that frequent the area starting in late fall and will extend their stay until late winter and early spring. These marine mammals spend about half their time in the water and the other on land. Delaware has witnessed a growing seal boom over the past few years, and while they offer a unique viewing experience, their time on the shoreline is critical for their survival and at times requires cooperation from people in order to allow them the much-needed rest they seek.
First, let’s take a look at the four different species that will often slink their way on land during their visits. They are the harbor seal, the gray seal, the harp seal, and the hooded seal.
Harbor Seal (Phoca vitulina): The most common species along the Delaware coastline are easily recognizable by their rounded heads and large, dark eyes. Harbor seals’ coat color can range from light gray to brown, often with spots or rings. Known for their adaptability, they are generally solitary and can be found relaxing on beaches and the breakwater walls off Cape Henlopen, sleeping off their meals of fish, squid, and crustaceans.
Harbor seals begin to arrive in Delaware in late fall through early spring, migrating south from the colder waters of the northern Atlantic. Adults are about 6 feet tall and can weigh more than 200 pounds.
Pups weigh about 25 pounds at birth. The first month is critical for them, as pups double their weight feeding off their mother’s nutrient-rich milk, which helps them gain that protective layer of blubber to keep their body temperature regulated. Mothers will often leave the pups to fend for themselves after that first month.
Gray Seal (Halichoerus grypus): Also known as the “horsehead” seal, given its rather elongated snout, is another common Delaware visitor. Gray seals are larger than harbor seals (males reach up to 10 feet and can weigh up to 850 pounds, and females can reach about 7.5 feet and weigh about 550 pounds).
When in the water, grays can be found exploring the coastal waters for fish, crustaceans, squid, and octopus. They will consume about four to six percent of their body weight daily and can dive to 230 feet on average. They can also hold their breath underwater for up to about 30 minutes.
Gray seal pups are born sporting stark white fur (called lanugo) but will quickly shed this for the mottled brown and silver adult fur.
Harp Seal (Pagophilus groenlandicus): Identifiable by the distinct harp-shaped markings on their backs, harp seals are less frequent visitors, as they prefer icier conditions, but will occasionally pop out onto the beaches of Delaware to rest or if injured.
Harp seals can travel vast distances between breeding and feeding grounds where they will commonly dine on smaller fish, krill, and crustaceans.
Young Harp seals nurse only for the first 12 days before embarking on their own. After about a month, they will lose their long white fur coat (that helps them absorb sunlight when on land), and because they have not yet developed hunting strategies, will survive off their fat reserves and could potentially lose about 50 percent of their body weight.
Hooded Seal (Cystophora cristata): The rarest of the four Delaware species, they are named for the large, inflatable sac on the males’ heads (which is essentially a built-in nose balloon and is inflated during courtship). Hooded seals are generally larger than harbor and harp seals but smaller than grays.
Hooded seals are typically solitary and generally prefer the colder Atlantic and Arctic waters but have been spotted as far south as the Caribbean outside breeding season. They are very territorial and can use their “nose balloon” underwater to ward off competition during feeding or mating.
Hooded seal pups have the shortest weaning period of any mammal, typically about 3 to 5 days, but can almost double their weight in that time thanks to their mother’s milk.
Conservation and Observation
All four species of seals are protected under the Marine Mammal Protection Act, which prohibits harassment or harm to these animals. They can typically be found in Delaware waters and on beaches from November through April, and even though this is normal, it is still a rare opportunity to catch sight of a seal in the wild. When contacted, members of MERR (Marine Education Research and Rehabilitation) Institute will help members of the public learn how to be responsible wildlife observers, and to view these amazing and entertaining creatures from a safe distance (at least 150 feet) as well as providing reminders to keep pets on a leash at this time for the protection of both the pet and seal.
If a member of the public encounters a seal resting on the beach or elsewhere, please call MERR immediately at 302.228.5029, and keep a distance of 150 feet. Seals will often spend about half their lives on land and rest is integral to their survival, regardless of its age, as females will often go for weeks without consuming food while they are nursing. Approaching them closely can frighten them and add stress, causing them to retreat into the water without the necessary rest.
MERR provides rescue and response for stranded marine animals that occur throughout the state of Delaware. MERR is a 501(c)(3) organization dedicated to the conservation of marine mammals and sea turtles and their habitat. If you notice a marine mammal or sea turtle in distress in Delaware, please contact MERR’s 24-hour hotline at 302.228.5029.
Rob Rector has served as naturalist and board member for 20 years, is a certified Protected Species Observer, and leads weekly dolphin observation tours that use citizen science to gather information on our local Bottlenose Dolphin populations.
