The Ungava seal (P.v. mellonae), also known as the Lacs des Loups Marins harbour seal, lives in a series of land-locked, inter-connected freshwater 'seal' lakes of the Ungava peninsula of northern Quebec, although it is thought that the distribution is now limited to only three lakes (DFO, 2009). The number of Ungava seals is unknown but is probably a few hundred at most (COSEWIC, 2007; DFO, 2009).The eastern Pacific harbour seal (P.v. richardii) population consists of ~235,000 seals, distributed from the Pribilof and Aleutian Islands in Alaska as far south as Baja California. The population in Alaska is estimated at ~180,000 (NOAA, 2011). The harbour seals at Tugidak Island in Alaska has been monitored intensively since the 1970s, and has shown a decline in seals ashore during the 1970s and 1980s, from more than 6,000 to fewer than 1,000, followed by a slight increase in the 1990s to ~1,500 by 2000. Pup production increased from ~150 to ~250 from 1994 to 2000 (Jemison & Kelly, 2001; Jemison et al, 2006). Total harbour seal numbers in Washington and Oregon are estimated at ~22,000, and in California at ~34,000 (NOAA, 2011). The abundance of the western Pacific harbour seal, or Kuril seal (P.v. stejnegeri) is thought to be about 3,000–3,500 in the Kuril Islands, a similar number in the Commander Islands, and about 350 in Hokkaido, northern Japan (Thompson & Härkönen, 2008), where numbers remain low due to by-catch in the salmon fishery and local shooting by fishermen (Wada et al., 1991).

Harbour seals have a rounded head and muzzle, with the adult bod shape resembling a larger version of juveniles. The pattern of harbour seal coats varies widely. The background colour is pale grey in a newly moulted anmal, shading to pale brown or tan as the next moult approaches, and appears spotted or speckled is covered with light or dark rings, spots and blotches. In P.v. vitulina the adults usually appear to be speckled when dry, while the juveniles up to about 3 years have a more homogeneous colour of pale beige when dry. Juveniles sometimes have dark rings around the eyes, giving the apearance of wearing spectacles when dry. The pattern of speckles or spots on a harbour seal's coat is unique to each seal and does not change from year to year, a potentially useful feature in the identification of individuals. A red to orange coloration, caused by the attachment of iron oxides to the external hair shaft, is also found in a number of seals, especially in San Francisco Bay (Allen et al, 1993) and in Walton in Essex.

Legal Status

The eastern Atlantic harbour seal is listed as an Appendix III species under the Bern Convention, and the subpopulations in the Baltic and Wadden Seas are listed as an Appendix II species under the Bonn Convention. The species is also listed as a protected species under Annex II and Annex V of the European Community's Habitats Directive, and several important sites for the harbour seal have been proposed in EC member countries as Special Areas of Conservation under the Directive. The harbour seal on both the east and western coasts of the US is protected under the Marine Mammal Protection Act (MMPA) 1972, as amended. The eastern and Arctic populations of the Western Atlantic harbour seal were added to Canada's Species at Risk list for 1999 with the the status Indeterminate. The harbour seal population in Mexico, about 1,000 to 3,000 individuals, is fully protected under the Ley General de Vida Silvestre NOM-059-ECOL-1994 which forbids the killing, collecting or possession of the species or any part or product obtained from the species.

The Ungava Seal has been assigned the status Vulnerable by the Committee on the Status of Endangered Wildlife in Canada, which describes it as a "unique endemic subspecies of harbour seals with limited range and low numbers, making it vulnerable to human impact and natural catastrophic events". It is thought that a proposed hydroelectric development may have an adverse impact on a large portion of the population's range by reducing the water level of the Lac des Loups Marins. The population currently has minimum legal protection in Canada and none of its habitat is protected. However the Quebec government is considering whether or not to give legal protection to a portion of the habitat. There is some occasional hunting of the seals by the local native peoples for subsistence purposes. The Ungava seal is listed as Data deficient on the IUCN Red List.

Conservation Status
Harbour seals in many areas remain in the vicinity of their traditional breeding sites all year round. This restricted range means that the viability of local or isolated harbour seal populations can be particularly at risk. A number of isolated populations have already disappeared, e.g. extermination of the Lake Ontario population by the early 1800s and the Faroe population by the mid-1800s, and catastrophic decline of the Sable Island population by the early 2000s (Bowen et al., 2003). The Baltic Sea population is considered to be a remnant of a formerly more widely distributed population (Helander and Bignert, 1992). Harbour seal colonies around Britain have been in decline during the past decade, with populations in Orkney and Shetland declining by as much as 40% over a 5-year period (Lonergan et al., 2007).

Threats

Seal-fisheries interactions

Many of the fish species eaten by harbour seals are also commercially fished, the resulting interactions between the seals and commercial fisheries being a source of mortality. Harbour seals can become entangled and drown in fishing nets and gear, especially by gillnet fisheries (e.g. Bjørge et al., 2002) and salmon trap fisheries (Wada et al., 1991). In several countries, such as Canada, Norway and the United Kingdom, it is legal to shoot harbour seals to protect fisheries or fish farms. Conservation groups are attempting to promote the development and use of humane non-lethal seal deterrence methods, including effective anti-predator nets on fish farms and the movement from open sea cage fish farms to land-based closed loop systems (eg Wilson and Pereira, 2009). An unknown level of illegal killing of harbour seals, mainly by fishing interests, also takes place throughout the species' range.

P.v.richardsi
Photos: Phillip Colla,
Phillip Colla Wildlife Photography

mother and pup

Juvenile

P.v.vitulina
Photos: Sue Wilson, Tara Seal Research

Culls of harbour seals are regularly called for by those who believe that the seals are eating too much fish, despite evidence showing that the simplified view of "fewer seals equals more fish" is misguided given the complexity of the marine food web (Wilson, 2003). Those opposing such culls say that the seals are being made scapegoats, and that overfishing, habitat alteration and marine pollution are the causes of dramatic decreases in fish stocks. Many seal populations are only just now recovering from bounty schemes and organised culling, most of which ended in the 1960s and 1970s (Wilson 2003).

Hunting

Environmental contaminants

There has been considerable concern as to the effects on harbour seals of environmental contaminants such as organochlorines. PCBs and DDTs were believed to be implicated in the near extinction of the harbour seals in the Baltic and the Dutch Wadden Sea (Helander and Bignert, 1992; Reijnders, 1985) and in reproductive failure and death of newborn pups in the estuary of the industrial River Tees in NE England (Wilson, 2001). A landmark experiment demonstrated that captive harbour seals fed fish from the polluted Dutch Wadden Sea suffered reproductve impairment, while seals fed fish from the north-east Atlantic reproduced normally (Reijnders, 1986). There was also a concern that the effects of the 1988 epizootic affecting the eastern Atlantic harbour seal may have been worsened by impairment of the harbour seals' immune systems by pollutants (Hall et al., 1992) and a series of experiments with feeding captive harbour seals on polluted and non-polluted herring demonstrated the levels of pollution in the fish that could cause immune impairment (de Swart et al, 1994).

The risk to harbour seals from oil and hydrocarbon contamination may be locally significant. In 1989 the oil spill from the tanker Exxon Valdez in Prince William Sound, Alaska, affected some of the largest harbour seal haulout sites in the area. It is thought that about a third of the harbour seals using oiled haulout sites were killed, and that pup production and survival were also affected. Not only did the seals become coated with oil and inhale volatile substances, but the oil was also incorporated in seal tissues, abnormal behaviour was experienced, and pathological brain damage occurred.Physical debris is an additional threat to harbour seals, individuals being killed throughout the species' range by entanglement in marine debris, particularly non-biodegradable fishing nets and plastic wrapping bands.

Infectious disease

In the spring and summer of 1988 an epidemic of phocine distemper virus (PDV), a morbillivirus closely related to canine distemper virus (CDV), swept through harbour seal populations in the east Atlantic, killing over 18,000 eastern Atlantic harbour seals (Osterhaus and Vedder, 1988). 5378 seals were found dead in the Kattegat-Skagerrak of a total population of about 9100, i.e. a 60% mortality (Härkönen and Heide-Jørgensen, 1990). This dramatic epizootic became one of the best-studied of wildlife disease outbreaks. A second wave of this same virus again killed thousands of seals in 2002 (Jensen et al., 2002).  In both cases the epidemic began at the Danish island of Anholt in the Kattegat, and subsequently spread to adjacent colonies in a step-wise manner infecting seals along the North Sea coasts, with the exception of seals in Norway and the Baltic. The origin of the epidemic may have been a mass migration of harp seals south to western Europe following the collapse of their diet staple capelin in the Barents Sea. Infection with PDV has been shown to be widepsread in harp seals from the Baents Sea and West ice (Markussen and Have, 1992). Harp seals were not seen at Anholt, but were seen at other harbour seal haul-outs in the North Sea. It is thought that grey seals may have been responsble for causing the virus to 'jump' to colonies, eg to the Irish Sea and the west of Ireland, remote from the epidemic source. Grey seals may carry the virus without showing symptoms, and form mixed haul-outs with harbour seals at many sites, including Anholt (Härkönen et al., 2006).

P.v.vitulina mother-pup pairs - left to right: nose-to-nose contact, suckling at water's edge, pup following in water, lone pup approaches mother-pup pair
Photo: Sue Wilson, Tara Seal Research

Pupping and pup development

Harbour seal pups are usually born close to the water's edge. Most pups are born with their adult coat, having shed a grey-white woolly coat before birth. Pups of some subspecies, however, are born with this pre-natal coat and moult it shortly afterwards. 16% of P.v. concolor pups on Sable Island are born with the lanugo coat (Boulva, 1971). Most harbour seal pups are born in the intertidal area, on rocky ledges or beaches subject to daily tidal flooding.

P.v.concolor, Sable Island. Mother play-bites pup's neck
Photo: Sue Wilson, Tara Seal Research

Despite their diving prowess, pups do not apparently actively forage for small prey until after they have stopped suckling and are completely weaned. Their first prey has been found to be small sandeels and gadoid fish of up to about 8cm long at Sable Island (Muelbert and Bowen, 1993) and, similarly in a colony in Ireland, small gadoid fish of average length 8 cm (Wilson et al., 2002). Most pups began feeding, on average 10 days post-weaning, although some pups (about 20%) fasted for about 3 weeks (Muelbert and Bowen, 1993). During the first month postweaning, pups at Sable Island lost an average 4 kg from an initial average of 24 kg at weaning, and apparently took about 4–6 weeks to achieve a positive energy balance (Muelbert et al., 2003).

P.v.concolor, Maine.  Clusters of weaned pups: 4 pups (left), 2 pups haul out together on small ledge (centre), 3 pups haul out together and approach adult male (right).  
Photo: Sue Wilson, Tara Seal Research

The annual moult

The harbour seal moult - for all seals older than pups - follows the pupping season. The moulting season usually lasts about 4–5 weeks, although the time of the moult for individuals may vary according to age, sex and reproductive status (Thompson and Rothery, 1987). During the moult the seals' skin heats up to aid the in the shedding and regrowth of their hair. They therefore spend as much time as possible hauled out during the moult in order to conserve heat and avoid excess energy loss. It is therefore important not to disturb moulting seals, as this may cause them to waste valuable energy as they escape into the water. 

Mating

Mating of harbour seals was first described at a readily visible colony of P. v. vitulina in Shetland (Venables and Venables, 1957). They observed sexual pairing taking place in September, between seals who had already completed their moult. From the beginning of September, as seals were completing their moult, seals became very active, leaping ('porpoising') and 'rifle shot' splashing at the surface, Actual coitus, seen on several occasions, was preceded by the pair 'rolling' over one another, and splashing. The pair then coiled downwards towards the sea bed, each seal blowing a fountain of bubbles. They either floated up again in the tail of the bubble stream and the interaction waned, or the male mounted the female, clasping her in the axillary region,and sometimes mouthing the back of her head. This usually happened underwater, close to the sea bed. Despite these observations, it is considered that the timing of harbour seal mating of P. v. vitulina in September probably does not apply to all populations. Thompson (1988) observed neck scarring in adult males, apparently caused by bites, peaking in July and declining through August to a low in September. He assumed that the neck wounds were due to fighting between males, which apparently occurred in the water offshore. He also assumed the fighting probably coincided with the mating period, which would then have been timed to coincide with the end of lactation in late July and early August. This would be compatible wth the post-lactation mating season in most other phocids. Observations by Allen (1985) of coitus in P.v. richardii in late May and early June, i.e. post-lactation and before the moult, support the theory that this may be the more common pattern and the Shetland pattern less usual. 

Adult males of P.v. richardii and P.v. concolor have been shown to produce an underwater 'roar', whch has different characteristics for different individuals (Hanggi and Schusterman, 1994). It is thought that males of P.v. richardii - hold underwater territories for mating, and that the 'roar' is a challenge from an intruding male, whch will produce an aggressive response (Hayes et al., 2004). Similar behaviour has ben described for P.v. vitulina males in Norway, where males were found to be calling in the deeper channels between haul-out sites used by mothers and pups (Bjørge et al., 1995). The most successful territories for P.v. richardii were held either offshore along the open coast or along the travel corridor to and from the haul-out site  Genetic studies, however, have shown that most males father no more than one pup in a season (Hayes et al., 2006). P.v. vitulina males in the Moray Firth in Scotland began to restrict their range of movements at the time of mid–late lactation, and engaged in diving and acoustic displays. Males differed in the display areas that they used, some staying close inshore and others moving further offshore (Van Parijs et al., 1997).

P.v. vitulina, Shetland. Two juveniles play 'rolling' in shallow water beside haul-out site
Photo: Sue Wilson, Tara Seal Research

P.v. vitulina, Ireland. An adult and a juvenile play at water's edge at haul-out site
Photo: Sue Wilson, Tara Seal Research

Social behaviour

Harbour seals have rich social lives, manifest by play behaviour close to the haul-out site (Wilson, 1974; Wilson and Kleiman, 1974). In the water, seals may play in pairs, 'rolling' by twisting and somersaulting over each other in continuous contact. This resembles pre-coital behaviour described by Venables & Venables (1957), but there is no mounting or detectable sexual element. The tempo of rolling may be fast, with much splashing, and may grade into slower movement, where the seals may hold one another with eyes closed. Rolling occurs in all age groups, including mother-pup, weaned pups, juveniles and adults. Play may also occur at the water's edge in just a few cm of water. Here the head-over-body play signal predominates, and play fighting may occasionally occur. This play behaviour is thought to enhance the social bond between individuals. Another type of play, called 'group play' may also occur as seals haul out. This involves less body contact, but much 'porpoising', 'streaking' (swimming rapidly at the surface, creating much foam), splashing and leaping on and off the rock as another seal approaches. Adults as well as juveniles may engage in play (Wilson, 1974; Renouf and Lawson, 1986). Group play probably enhances the bonding between group members, and the 'boisterous exaggeration' of play locomotor movement may produce vestibular stimulation (Renouf and Lawson, 1986).

The haul-out group

The functions of the harbour seal haul-out group may be various. A group of seals resting on a haul-out maintains a more effective vigilance than seals hauled out alone. Another function may be as an 'information centre' When seals return to the water, they may follow their neighbour to a successful foraging area. Whatever its functions, it is likely - given the site fidelity of animals over many years, and the relatively small group size  - that individual seals in a group 'know' each other and there may be social bonding to a greater or lesser extent between different individuals of different ages or sexes within a group. Some haul-out groups in some populations are dominated by one age or sex class. Some groups comprise mainly mothers and pups, some mainly adult males and some mainly juveniles (Wilson, 1974a,b; Wilson & Kleiman, 1974; Thompson, 1989; Kovacs, Jonas and Welke, 1990). Within mixed age/sex haul-out groups of P.v. richardii, seals may be segregated by age and sex, and this may be most pronounced during te pupping period, when new mothers tend to be intolerant of the proximity of males and juveniles (Allen et al., 1988). Social cohesion is not readily visible when animals are studied only while they are hauled out and resting (Davis and Renouf, 1987), and - especially in large colonies such as that formerly on Sable Island - stable social units were not evident from the structure of haul-out groups (Godsell, 1988). The reason for this is that most cohesive social interaction between harbour seals occurs either in the water or within the splash zone at the water's edge - once the seal haul out to rest, their position relative to other seals on the beach often seems to be relatively unimportant.     

Foraging and diet

Harbour seals are opportunistic foragers, feeding in coastal shallow waters on locally and seasonally abundant prey, mostly fish, but also shrimps and small cephalopod molluscs. The seals forage mainly close to the seabed, mainly on small groundfish including gadoid fish (such as whiting, pollock, poorcod) flatfish (such as plaice and flounder), sandeels, herring and sprat. They usually select small fish which can be swallowed whole. A 'crittercam' fitted to the back of seals at Sable island revealed foraging tactics of adult males (Bowen et al., 2002). The seals foraged for sandeels by cruising at medium speed 1–2m from the seabed, and caught fish by thrusting their heads towards the bottom nas sandeels appeared, or routing in the sand for several seconds. They also occasionally dug in the sand using their foreflippers. They used similar tactics for foraging for flounders. They sometimes regurgitate underwater and then eat the regurgitated fish again - possibly to eliminate some sand and seawater. They also foraged on sandeel schools by breaking the school into smaller units, or separating individuals at the edge of the school and then pursuing isolated individuals. The foraging tactics can be broadly classified into 'sit-and-wait' ('ambush') and active searching, and varied acording to the visibility, speed and behaviour of the prey. The smallest prey were the least profitable to pursue in terms of energy, which emphasises the struggle experienced by young pups in achieving a positive energy balance during their first 6 weeks post-weaning, since they evidently 'learn' their first foraging skills on the smallest prey. 

Harbour seals are often accused of affecting stocks of valuable commercial fish, such as salmon and cod, and have frequently been shot by fishermen for this reason. The numerous studies of harbour seal diet in many parts of their range (of whch a few are cited here) have generally found salmonids to be a non-existent or negligable part of the diet (Pierce et al., 1997). However, there are exceptions, and salmon are occasionally a small and seasonal part of the diet of harbour seals living in the vicinity of salmon rivers, though rarely away from nets (Pierce et al., 1991). Salmon comprised a total of 4% of the diet by weight of a colony of P.v. richardsii in British Columbia (Olesiuk, 1993) and 9% in a colony of P.v.vitulina in a Loch on the west of Scotland (Boyle, 1990). However, studies of the foraging behaviour of harbour seals in the Moray Firth in Scotland showed that they targeted shoals of sprat and small herring duing the day when they were densely packed near the seabed (Thompson et al. 1991). Adult and juvenile salmonids may therefore only be attractive to seals when moving in relatively large concentrations along the coast and when confined in river estuaries. Even when hauled out near salmon river estuaries, harbour seals have been found to feed routinely on non-salmonid sea fish  (Pierce at al., 1997).

The collapse of the cod fishery in the Skagerrak and Kattegat in the latter half of the 20th century, and this coincided with an increase in the harbour seal population, due to a reduction in human persecution. This led to renewed calls for seal culling. However, analysis of the magnitude of cod-seal interaction concluded that harbour seals have a negligable effect on the commercial cod fishery (Hansen and Harding, 2006).

Statistics
East Atlantic harbour seals show very little sexual dimorphism, although adult males may be slightly larger and have a slightly broader head than females. A sample of adult male P. v. vitulina in Ireland (caught for tagging) weighed between 73 and 103 kg, while females (some of whom may have been in late pregnancy) weighed 73-94kg (B. McConnell, pers. comm). This is consistent with weights of 88–91kg and 73–77kg for males and females respectively from the Norwegian coast in the summer (Markussen et al, 1989), and 75 and 67kg for males and females respectively in the Kattegat-Skagerrak, although weights fluctuate during the pupping and moulting seasons (Härkönen and Heide-Jørgensen, 1990). Pups are usually born measuring ~70-90cm in length and weighing ~11kg on average (King, 1983; Coltman et al., 1998; Cottrell et al., 2002), although lower average birth weight of 8.7kg is reported from the Kattegat-Skagerrak (Härkönen and Heide-Jørgensen, 1990). Body weight in nursing pups at different ages up to weaning was equal to the birth weight plus 0.5kg x age in days (Markussen et al., 1989). An average weaning weight at 3–4 weeks of 24kg for males, 20kg for females has been reported for Sable Island (Boulva, 1971) and ~20 kg for the Wadden Sea (Drescher, 1979). At 10-12 weeks after weaning, male pups in the Kattegat-Skagerrak weigh ~24 kg and are slightly heavier than females; males continue to gain weight to ~30kg at one year, while females maintain their 5-month-old weight at one year (Härkönen and Heide-Jørgensen, 1990).  Most male harbour seals are thought to reach sexual maturity at 6-7 years of age, females at about 4–5 years (Boulva and McLaren, 1979; Härkönen and Heide-Jørgensen, 1990). The average annual pregnancy rate for females is 92% from sexual maturity until age 36, but the rate may fall after the age of 25 (Härkönen and Heide-Jørgensen, 1990).

Pupping seasons vary for different populations, with mean birth dates ranging from 15 March to Sept 3 (Temte et al., 1991). The range for the east Atlantic P. v. vitulina estimated by these authors was June 16 to July 17; for the west Atlantic P. v. concolor, including Greenland, the mean dates were earlier, from May 02 to July 10. The Ungava seal pupping dates are mid-April to mid-May. For the east Pacific P. v richardsi the dates varied according to latitude, between March 25 and May 07 between Mexico to Washington State, between July 25 and August 13 in British Columbia and from BC to Alaska between June 17 and July 08. Mean pupping for P.v. stejnegeri takes place between May 25 and June 05 (Temte et al., 1991).

A gradually earlier pupping season for P.v.vitulina in the Wadden Sea has been documented since the early 1970s, with the birth date shifting on average by 0.71 days/year between 1974 and 2009. It was deduced that probably the embryonic diapause (period of delayed implantation after mating and fertilistion) has been shortened, possibly because of more small fish available to females during the post-mating period, this being possibly due to overfishing of adult and larger predatory fish (Reijnders et al., 2010).

Watch a Sable Island harbour seal fitted with a 'crittercam' foraging on sandeels 

La Jolla Friends of the Seals video explaining the origins of the seals and the controversy

Video explaining the controversy at La Jolla

Video of harbour seal colony at La Jolla beach (undisturbed)

Video of small harbour seal colony on a beach at Fitzgerald Marine Reserve. Note the greater social activity of seals at the water's edge

Video of harbour seal birth at La Jolla (1). The pup is born at the water's edge. The video shows nosing contacts by the mother just after birth, the pup's high activity level and ability to swim immediately after birth, the mother's chaperoning behaviour, and the hovering of a gull anticipating the afterbirth. Judging by the soundtrack, the human audience may have been rather too close and too loud in its cheering at the moment of birth.

Video of a harbour seal birth at La Jolla (2). This time the pup was born on a dry part of the beach. The amniotic sac is clearly seen. Again, a gull is waitng for the afterbirth.

Video of older harbour seal pup activity at water's edge (probably also at La Jolla).