P. vitulina concolor(DeKay, 1842) P. vitulina mellonae(Doutt, 1942) P. vitulina richardii(Gray, 1864) P. vitulina stejnegeri(J. A. Allen, 1902) P. vitulina vitulina(Linnaeus, 1758)
Range ofPhoca vitulina
Theharbor (orharbour)seal (Phoca vitulina), also known as thecommon seal, is atrue seal found along temperate and Arctic marine coastlines of theNorthern Hemisphere. The most widely distributed species ofpinniped (walruses, eared seals, and true seals), they are found in coastal waters of the northernAtlantic andPacific oceans,Baltic andNorth seas.
Harbor seals are brown, silvery white, tan, or gray, with distinctive V-shaped nostrils. An adult can attain a length of 1.85 m (6.1 ft) and a mass of up to 168 kg (370 lb).Blubber under the seal's skin helps to maintain body temperature. Females outlive males (30–35 years versus 20–25 years). Harbor seals stick to familiar resting spots or haulout sites, generally rocky areas (although ice, sand, and mud may also be used) where they are protected from adverse weather conditions and predation, near a foraging area. Males may fight over mates under water and on land. Females bear a single pup after a nine-month gestation, which they care for alone. Pups can weigh up to 16 kg (35 lb) and are able to swim and dive within hours of birth. They develop quickly on their mothers' fat-rich milk, and are weaned after four to six weeks.
The global population of harbor seals is 350,000–500,000, but the freshwater subspeciesUngava seal in Northern Quebec is endangered.[1] Once a common practice,sealing is now illegal in many nations within the animal's range.
Skull of a harbor sealSkeleton of a harbor seal in the Seal Museum inIceland
Individual harbor seals possess a unique pattern of spots, either dark on a light background or light on a dark. They vary in colour from brownish black to tan or grey; underparts are generally lighter. The body and flippers are short, heads are rounded. Nostrils appear distinctively V-shaped. As with other true seals, there is nopinna (ear flap). An ear canal may be visible behind the eye. Including the head and flippers, they may reach an adult length of 1.85 m (6.1 ft) and a weight of 55 to 168 kg (120 to 370 lb).[3] Females are generally smaller than males.
There are an estimated 350,000–500,000 harbor seals worldwide.[1] While the population is not threatened as a whole, theGreenland,Hokkaidō andBaltic Sea populations are exceptions. Local populations have been reduced or eliminated through disease (especially thephocine distemper virus) and conflict withhumans, both unintentionally and intentionally. Killing seals perceived to threatenfisheries is legal inNorway, andCanada, but commercial hunting is illegal. Seals are also taken in subsistence hunting and accidentally asbycatch (mainly in bottomset nets). Along the Norwegian coast, bycatch accounted for 48% of pup mortality.[4] Killing or taking seals has been illegal in the United Kingdom since 1 March 2021.[5]
The California population of subspeciesP. v. richardii amounted to about 25,000 individuals as of 1984. Pacific harbor seals or California harbor seals are found along the entire Pacific Coast shoreline of the state. They prefer to remain relatively close to shore in subtidal andintertidal zones, and have not been seen beyond theChannel Islands as apelagic form; moreover, they often venture into bays and estuaries and even swim up coastal rivers. They feed in shallowlittoral waters onherring,flounder,hake,anchovy,codfish, andsculpin.[6]
Breeding occurs in California from March to May, with pupping between April and May, depending on local populations. As top-level feeders in thekelp forest, harbor seals enhance species diversity and productivity. They are preyed upon bykiller whales (orcas) andwhite sharks. Haul out sites in California include urban beaches and from time to time they can be seen having a nap on the beach in all of San Francisco Bay, which would include the conurbation ofRichmond,Oakland, andSan Francisco, theGreater Los Angeles area, which would includeSanta Barbara, the city ofLos Angeles itself, andLong Beach, and all ofSan Diego Bay, most famously beaches nearLa Jolla.[7][8][9][10][11][12]
Considerable scientific inquiry has been carried out bythe Marine Mammal Center and other research organizations beginning in the 1980s regarding the incidence and transmission of diseases in harbor seals in the wild, including analysis of phocineherpesvirus.[13] InSan Francisco Bay, some harbor seals are fully or partially reddish in color, possibly caused by an accumulation of trace elements such as iron or selenium in the ocean, or a change in the hair follicles.[14]
Although some of the largest harbor seal pupping areas are found in California, they are also found north along the Pacific Coast in Oregon, Washington, British Columbia and Alaska. Large populations move with the season south along the west coast of Canada and may winter on the islands in Washington and Oregon. Pupping is known to occur in both Washington and Oregon as of 2020. People are advised to stay at least 50m away from harbor seals that have hauled out on land, especially the pups, as mothers will abandon them when there is excessive human activity nearby.[15]
A Harbor Seal nursery on ice in front of The Grand Pacific Glacier in Glacier Bay National Park, Alaska
Historically, the range of the harbor seal extended from the mouth of the St. Lawrence River and Greenland to the sandy beaches of North Carolina, a distance of well over a thousand miles (greater than 1600 km) Evidence of their presence in these areas is consistent with both the fossil record as well as a few landmarks named for them during colonization: Robbin's Reef, off of Bayonne, New Jersey, gets its name from the Dutch wordrobben, meaning "seals". On the border between Canada and the US is an island known asMachias Seal Island, a place where today the harbor seal will occasionally visit but is now a sanctuary for puffins. Over the course of hundreds of years, however, the seal was wiped out steadily by being shot on sight by fishermen and by massive pollution. The evidence for this is found in documents all along the coast of New England which put a bounty on the head of every seal shot, as well as the accounts of harbormasters. New York City, when it was founded in the 1640s, was founded on top of an enormous estuary teeming with life that included the harbor seal. Oil in the 1800s started the process of pollution that was later compounded by even more toxic 20th century chemicals that includedPCB's anddioxin. By the time of the1972 Clean Water Act, New York Harbor was almost dead-almost no living thing could survive in it.[16] Approximately 300 miles to the north,Boston Harbor was equally polluted. Raw sewage had been dumped in the harbor since the late 1800s and the stench of fecal matter in the Charles River was overpowering, as evidenced by the song "Dirty Water" by theStandells, written in 1966. Flatfish, abundant in the area, had enormous tumors in their livers by the 1980s and the harbor seal was long gone, shot to oblivion.[17]
As of 2020, however, the seals have returned. They never were extirpated from Canada and certain pockets of the Maine coast, and thus an important mother population was created from whence the species could reclaim the home of their ancestors. Currently, they are sighted as far south as the barrier islands of North Carolina on a regular basis,[18] with Massachusetts being the southernmost point of known pupping areas along the Atlantic Coast.[19] Harbor seals move south from eastern Canadian waters to breed along the coast ofMaine,Cape Cod, and theSouth Shore in Massachusetts in May and June, and return northward in fall. Others will head south from these areas to "vacation" in warmer waters, particularly young seals unable to compete with adults for food and territory; they do not return north until spring.
One park ranger in New York City, which is dead center of its West Atlantic range, says that "New York is like their Miami resort."[16] This refers to the habit of young seals leaving Cape Cod and even some Arctic waters to inhabit the harbor in winter. In 2018 theNew York Post reported that the harbor is now "cleaner than it has been in 110 years,"[20] and since the first decade of the 21st century, the harbor seal has found the old turf of its ancestors to be a land of plenty and the water to be livable. Within sight of the New York skyline, known colonies of harbor seals are found onHoffman[21] andSwinburne Islands[22] as well as portions ofRed Hook[23] andStaten Island,[24] readily hauling out every from October until very early May. Known favorite foods of the seal are returning in grand numbers to New York Harbor as well as nearby New Jersey, fromRaritan Bay all the way down the entireJersey Shore, with schools ofmossbunker regularly attracting harbor seals, their cousins the grey seals, dolphins and, most recently, whales.[25] Both the northern and southern shores ofLong Island have a reliable population of harbor seals as well as greys, where they will take sand lance as well as some species of crab as part of their diet.
inhabit eastern North America. The validity of this subspecies is questionable, and not supported by genetic evidence. They might be part of the Eastern Atlantic subspecies.[26]
Harbor seals prefer to frequent familiar resting sites. They may spend several days at sea and travel up to 50 km in search of feeding grounds, and will also swim more than a hundred miles upstream into fresh water in largerivers in search of migratory fish likeshad and likelysalmon.[citation needed] Resting sites may be both rugged, rocky coasts, such as those of theHebrides or the shorelines ofNew England, or sandy beaches, like the ones that flankNormandy in Northern France or theOuter Banks of North Carolina.[1] Harbor seals frequently congregate in harbors, bays, sandy intertidal zones,[1] andestuaries in pursuit of prey fish such assalmon,[28]menhaden,anchovy,sea bass,herring,mackerel,cod,whiting andflatfish, and occasionallyshrimp,crabs,mollusks, andsquid. Atlantic subspecies of either Europe or North America also exploit deeper-dwelling fish of the genusAmmodytes as a food source and Pacific subspecies have been recorded occasionally consuming fish of the genusOncorhynchus. Although primarily coastal, dives of over 500 m have been recorded.[29] Harbor seals have been recorded to attack, kill and eat several kinds of ducks.[30]
Harbor seals are solitary, but are gregarious when hauled out and during the breeding season, though they do not form groups as large as some other seals. When not actively feeding, theyhaul to rest. They tend to be coastal, not venturing more than 20 km offshore. The mating system is not known, but thought to bepolygamous. Females give birth once per year, with agestation period around nine months. Females have a mean age at sexual maturity of 3.72 years and a mean age at first parturition of 4.64.[31] Bothcourtship andmating occur under water.[32][31] Researchers have found males gather under water, turn on their backs, put their heads together, and vocalize to attract females ready for breeding.[33] Pregnancy rate of females was 92% from age 3 to age 36, with lowered reproductive success after the age of 25 years.[31]
Birthing of pups occurs annually on shore. The timing of the pupping season varies with location,[34] occurring in February for populations in lower latitudes, and as late as July in the subarctic zone. The mothers are the sole providers of care, with lactation lasting 24 days.[35] The single pups are born well developed, capable of swimming and diving within hours. Suckling for three to four weeks, pups feed on the mother's rich, fatty milk and grow rapidly; born weighing up to 16 kilograms, the pups may double their weight by the time ofweaning.
Harbor seals must spend a great deal of time on shore whenmolting, which occurs shortly after breeding. This onshore time is important to the life cycle, and can be disturbed when substantial human presence occurs.[36] The timing of onset of molt depends on the age and sex of the animal, with yearlings molting first and adult males last.[37] A female mates again immediately following the weaning of her pup. Harbor seals are sometimes reluctant to haul out in the presence of humans, so shoreline development and access must be carefully studied, and if necessary managed, in known locations of seal haul out.[citation needed]
In comparison to many pinniped species, and in contrast to otariid pinnipeds, harbor seals are generally regarded to be more vocally reticent. However, they do utilize non-harmonic vocalizations to maintain breeding territories and to attract mates during specified times of year,[38] and also during mother and pup interactions.[39]
Annual survival rates were calculated at 0.91 for adult males,[31] and 0.902 for adult females.[40] Maximum age for females was 36 and for males 31 years.[31]
Hoover, also rescued from a Maine harbor. Hoover became famous for his ability to imitate human speech, something not observed in any other mammal.
Popeye, the official seal ofFriday Harbor, Washington, notable for her common sightings up until 2019, when she was presumed to have died. She was identified and named for her cloudy left eye. There is a statue of her in the Port of Friday Harbor.
Freddie, a seal pup commonly spotted along the Thames in central London. Named afterFreddie Mercury due to his bushy whiskers and playfulness. Freddie was known to travel unusually far into London from the Thames Estuary, and was often sighted as far west asHammersmith. On 21 March 2021 he had to be put down after he was violently mauled by an out-of-control dog.[41]
^Newby, T.C. (1978).Pacific Harbor Seal pp 184–191 in D. Haley, ed.Marine Mammals of Eastern North Pacific andArctic Waters, Pacific Search Press, Seattle WA.
^Berta, A.; Churchill, M. (2012). "Pinniped Taxonomy: evidence for species and subspecies".Mammal Review.42 (3):207–234.doi:10.1111/j.1365-2907.2011.00193.x.
^Burns, J.J. (2002). Harbor seal and spotted sealPhoca vitulina andP. largha. In: W.F. Perrin, B. Wursig and J.G.M. Thewissen (eds),Encyclopedia of Marine Mammals Academic Press. pp. 552–560.
^abcdeHärkönen, T.; Heide-Jørgensen, M.-P. (1990-12-01). "Comparative life histories of East Atlantic and other harbour seal populations".Ophelia.32 (3):211–235.doi:10.1080/00785236.1990.10422032.ISSN0078-5326.
^Van Parijs, S.M.; Kovacs, K.M. (2002). "In-air and underwater vocalizations of eastern Canadian harbour seals,Phoca vitulina".Canadian Journal of Zoology.80 (7):1173–1179.doi:10.1139/z02-088.
^Temte, J. L. (1994). Photoperiod control of birth timing in harbour seal (Phoca vitulina).Journal of Zoology (London) 233: 369–384.
^Daryl Boness and W. Don Bowen, "The Evolution of Maternal Care in Pinnipeds", BioScience. 46(9):645-654. 1996.JSTOR1312894
^Patrick Sullivan, Gary Deghi and C.Michael Hogan,Harbor Seal Study for Strawberry Spit, Marin County, California, Earth Metrics file reference 10323, BCDC and County of Marin, January 23, 1989.
^Perry, E. A. & Renouf, D. (1988). "further studies of the role of harbour seal (Phoca vitulina) pup vocalizations in preventing separation of mother-pup pairs".Canadian Journal of Zoology.66 (4):934–938.doi:10.1139/z88-138.
^Manugian, S. C.; Greig, D.; Lee, D.; Becker, B. H.; Allen, S.; Lowry, M. S. & Harvey, J. T. (2017). "Survival probabilities and movements of harbor seals in central California".Marine Mammal Science.33 (1):154–171.Bibcode:2017MMamS..33..154M.doi:10.1111/mms.12350.
van den Toorn, Jaap (1999-09-21)."Harbor seals". Jaap's Marine Mammal Pages. Archived fromthe original on 2006-03-11. Retrieved2006-06-26.
California Wildlife, Volume III,Mammals, edited by David C. Zeiner, William F. Laudenslayer and Kenneth E. Meyer, published by theCalifornia Department of Fish and Game, Apr., 1990.
CRC Handbook ofMarine Mammal Medicine. edited by Leslie A Dierauf, Frances M D Gulland, CRC Press (2001)ISBN0-8493-0839-9
Hewitt, Joan (2002).A Harbor SealPup Grows Up. Carolrhoda Books.ISBN1-57505-166-4
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