Meet the Species
Learn about the species that our Marine Mammal Rescue team responds to most frequently.
Seal species seen in the coastal waters of New England include the harbor, gray, harp, and hooded seals, depending on the time of year. It is normal for seal species to be seen on land. Whales, dolphins, and porpoises are also present in New England waters but rarely strand on land. Annually, seals encompass approximately 95% of the SSC Marine Mammal Rescue caseload, and cetaceans (whales, dolphins, porpoises) encompass approximately 5%.
Harbor Seal Phoca vitulina
Harbor Seals are the most commonly seen seal species in our response territory. This is because they are year-round residents of the east coast, and they commonly haul out on land. The distinguishing feature of the harbor seal is a short, blunt dog-like snout. Their coloring varies, but they are generally a light to dark gray with darker spotting. When hauled out on land, they tend to rest in a “banana-like” position, elevating their head and hind flippers. Males are generally larger than females, measuring approximately 5 feet and weighing up to 245 pounds. Females give birth in our area in May-June and pups wean from their mother after 3-4 weeks. Harbor seal pups can swim shortly after birth and can dive for up to 2 minutes when they are just 2-3 days old.
Gray Seal Halichoerus grypus
Gray Seals are the other year-round species in our response territory. The distinguishing feature of the gray seal is its long snout, which is why they are sometimes referred to as “horseheads.” Gray seals are much larger than harbor seals, and male gray seals are significantly larger than females. Males can reach up to 8 feet in length and weigh in at a hefty 800 pounds. Females can reach up to 7 feet and 550 pounds. Females give birth north of New Hampshire in January and February. Pups are born with a creamy white coat that they shed after 2-3 weeks, and they wean from their mother after 2-3 weeks. The coat of an adult female is a silver-gray color with dark spots, and males have a dark gray coat with lighter spots. Gray seals can hold their breath for over an hour.
Hooded Seal Cystophora cristata
Hooded seals are considered ‘ice seals,’ only visiting the area in the winter months, and are the seal species the Marine Mammal Response team receives sightings of most rarely. Male hooded seals are easily distinguished from females and other seals because of the inflatable sac on their head, which extends from the crown of their head to their upper lip. This “hood” is inflated to attract females’ attention during mating season and to establish dominance and display hostility toward other males. Males are larger than females, measuring up to 8.5 feet and weighing up to 800 pounds. Females give birth in March and April on pack ice, and pups are often called “bluebacks” because their coat is blue-gray on the back with a whitish belly. They shed this coat after approximately 14 months when they molt to their adult coat, a gray coat with dark irregular blotches and a dark head. Pups are weaned after only 3-4 days, the shortest weaning period of any mammal, and during these first few days, their body weight nearly doubles.
Harp Seal Pagophilus groenlandicus
Harp seals are the more commonly seen ‘ice seal’ species, and juveniles are seen in this area more commonly than adults. Their distinguishing feature is the dark harp-like shape on the coat of adults. Adult harp seals are approximately 5-6 feet long and weigh around 300 pounds. Females give birth on pack ice in late February to March. Harp seal pups are distinctive for their all-white coat with long wool-like fur called lanugo. They go through a series of molts, and the coat of an older pup will be gray-tan with darker spots before they achieve their adult coloring consisting of a light gray coat with a dark/black face and a dark horseshoe-shaped pattern on their back (less distinct in females). Pups are with their mothers for approximately 12 days, nursing on high-fat milk before weaning. During this time, pups gain about 5 pounds per day and weigh about 80 pounds when they are weaned. Pups lose about half of this body weight during the weeks after weaning because the mother leaves her pup on the ice, where it remains, without eating, for approximately six weeks before retreating to the water to find food!
Atlantic White-Sided Dolphin Lagenorhynchus acutus
Atlantic white-sided dolphins are year-round residents of New England. They have a robust body, short beak, and tall dorsal fin and are distinguished by their distinct color pattern and bi-colored beak. They can grow to be 8.5 feet and weigh up to 500 pounds. Females give birth in June or July, and they lactate for 12-18 months. They are very social and playful, often seen in groups, and often mingle with other cetaceans such as pilot, humpback, and fin whales. Their back, flippers, fluke, and the top of their beak are black, while their belly and lower beak are white. Their sides are gray, and they have a distinct yellow-tan patch on their tail stock. They also have a black stripe from the corner of their mouth to the front of the flipper.
Harbor Porpoise Phocoena phocoena
Harbor porpoises are typically seen in our area from December to April. They are easily distinguished from dolphins because they do not have a distinct beak. They have a short, robust body, a short triangular dorsal fin, and a short blunt beak. Harbor porpoises can grow to 5.5 feet and weigh up to 170 pounds, with females being slightly larger than males. Young harbor porpoises are weaned after 8-12 months. A harbor porpoise has a dark gray back and white belly.
Short-beaked Common Dolphin Delphinus delphis
Short-beaked common dolphins are year-round residents of New England. They have a sleek, robust body, prominent beak, and a tall pointed dorsal fin. They can grow to be 8 feet long and up to 440 pounds. They are found offshore in large social groups and often associate with schools of tuna and feeding flocks of seabirds. Females give birth in May, June, or July, and lactation lasts for about four months. They have a black back and white belly, with a distinct crisscross pattern on their sides. The front/beak area of the crisscross pattern is a yellowish-tan color, and their back/fluke end is gray. They also have a black stripe from the corner of their mouth to the front of the flipper and a black eye patch.