Bearded Seal
(Erignathus barbatus)
IUCN STATUS (2010) - LEAST CONCERN
So named because of their long whiskers, the ice-inhabiting bearded seals are found around Greenland, Hudson Bay, the Arctic Ocean and adjacent seas up to a northern limit of 80-85 ° N (King, 1983; Kelly, 1988). There are two recognized subspecies of bearded seal. The E. barbatus barbatus subspecies is found in the western Laptev Sea, Barents Sea and north Atlantic Ocean as far south as the Gulf of St. Lawrence in the western Atlantic and Iceland / Norway in the eastern Atlantic, individuals occasionally found wandering as far south as Shetlandand the West European continental coast (Bree 2000). The E. barbatus nauticus subspecies inhabits the remainder of the Arctic Ocean, as well as the Bering and Okhotsk Seas, being found as far south as Hokkaido and, very occasionally, China (Rice, 1988).
There is currently no up-to-date overall population estimate for bearded seals. Estimates have been made of 300,000 for E. barbatus barbatus in the early 1970s, and of 450,000 for E. barbatus nauticus in the early 1980s (Burns, 1981).
The dynamics of bearded seal populations have not been reported, probably due to difficulty in surveying this widespread species. The effects of natural events and human-caused activities on the abundance is therefore not known. The bearded seal has long been subjected to hunting by Arctic coastal communities for food, clothing and other subsistence purposes. In recent years up to 7-12 thousand seals are allowed to be killed each year by the Russian government (Burdin, 2009). Bearded seals are also hunted by Alaskan natives but there are no reliable up-to-date figures on the extent of this hunting. Partial data for the United States indicate an annual kill of 6,800 seals in 2000 (Angliss and Outlaw, 2005). However this does not include other areas where bearded seals are an important component of the diet. Local hunting also takes place in Canada (Cleator (1996) estimated that roughly 2,400 bearded seals were taken per year). The hunts in Greenland take about 500-1,000 (Reijnders et al., 1993) seals per year. These figures do not include seals that are lost during hunting because they sink when killed and cannot be retrieved.
The bearded seal is listed as an Appendix III species under the Bern Convention (Kovacs and Lowry, 2008), therefore any exploitation must be regulated to keep the populations out of danger, and indiscriminate means of killing are prohibited. However, the Bern Convention’s applicability to seals in the Arctic is limited. Currently, of the European seal-hunting nations, only Norway is signatory to the Convention, while Russia is not, and Greenland, though part of Denmark, is not committed to the EU legislation.
A major concern at the moment is probably the effects that changes in the Arctic climate may be having on the bearded seal's environment, both through changes in water flow and the transport of nutrients through the Bering Strait, and also the loss of ice habitat caused by such factors as global warming (Kovacs and Lydersen, 2008). In addition there are concerns that oil and gas exploration and extraction in many parts of the species' range, particularly in the Chukchi and Beaufort Seas and the North Sea Route, may cause disturbance to bearded seals as well as possible pollution of the seals, their habitat and their food supply (Wiig et al., 1996; Pagnan, 2000). There is a potential for conflict between bearded seals and commercial fisheries, particularly in the central Bering Sea for species such as clams, tanner crabs and large snails/whelks, which are all components of the bearded seal diet.
The coat of the bearded seal is generally grey to brown and unpatterned. The seal has a noticeably small head in relation to its large size and has square-shaped foreflippers. The bearded seal shares two features with monk seals, which are unusual for phocid seals - they have straight, no-beaded whiskers and they have four teats instead of the usual two (King, 1983).
Bearded seals are usually found singly in seasonally ice-covered waters. During the ice season they prefer to inhabit areas of broken pack ice and drifting ice floes, but are quite versatile and also occur in areas of shorefast ice and thick ice where they are able to maintain breathing holes. Many of the seals move long distances to follow the receding ice in the summer (Kovacs, 2002). They are known, for example, to move from the White and Kara Seas to the northern Barents Sea and from the Bering Sea to the Chukchi Sea. In other areas such as the Laptev, Okhotsk and White Seas they do not follow the ice, but spend the summer in open water, sometimes hauling out on land, preferably on gravel beaches (Burns, 1981). Bearded seals have also been reported as hauling out and swimming in rivers that empty into Hudson Bay (Kelly, 1988; Kovacs, 2002). Young bearded seals in Alaska may be found in open water, not associated with ice, in summer and autumn.
When hauled out on an ice floe, bearded seals are characteristically seen at the edge of the floe with their head pointing towards the water and downwind. In such as position a seal can move rapidly into the water, can hear and smell what is behind it and see what is in front. Thus this position gives maximum protection aganst polar bear attack (Kingsley and Stirling, 1991).
Pupping and moulting take place on the ice. Most pups are born from mid-March to early May, later in the north than in the south. Pups are often born on small ice floes immediately adjacent to open water, thus making them less vulnerable to polar bear predation than if they are born on fast ice (Kovacs et al., 1996). Pups at Svalbard are born with a mixture of soft, wavy, long ~30mm grey lanugo hair that is actively shedding during the nursing period, and a shorter, stiff-hair coat ~20mm that is not loose. Some, but not all, of the lanugo is moulted in utero (Kovacs et al., 1996). There is often a lighter region down the centre of the back and some white on the snout and crown (King, 1983; see photo above). Kovacs et al (1996) describe a newborn pup entering the water when it was 2h old and swimming with its mother for short periods. Every 3h this pup called to its mother, who then hauled out on to the ice floe and nursed it. A study of four nursing pups (Lydersen et al., 1994) found that they spent about 53% of the time in the water, and were submerged for 42% of that time. Dives averaged ~10m and ~62s, and increased with age. The four pups moved with their mothers over a range of nearly 20km between the head and the mouth of the fjord. The mothers appeared to guide their pups away from drifting pack-ice and into more sheltered waters near the edge of the fast ice (Hammill et al., 1994). The early aquatic ability of the pups may have evolved as a means of escaping predation by polar bears (Kovacs et al., 1996; Kovacs, 2002) and is facilitated by the rapid neonatal loss of the heavy lanugo coat, which has no thermal insulating value when it is wet, but would cause considerable drag in the water.
The pup is nursed for about 18-24 days, although this time may vary. It gains weight very quickly at about 3.3kg/day (Lydersen et al., 1996). Weaning seems to be less abrupt than in most phocid species, with some pups learning to catch small prey while they are still nursing (Lydersen et al., 1996). The mother ovulates towards the end of the nursing period and mates around that time. The adult male has a very audible and musical underwater call during the breeding period and it is thought that this call is a means of signalling his underwater territory and/or his breeding condition. Moulting usually takes place after mating, between March and May according to the location (King, 1983).
Bearded seals are benthic foragers, preferring to feed at the seabed at water depths of less than 100m (Gjertz et al., 2000) although foraging dives of 130-200 m have been reported (Kosygin 1971 cited in Burns, 1981, Kelly, 1988). A study of the stomach content of 78 seals in the Bering Sea in early spring 1981 (Antonelis et al., 1994) found that 86% of stomachs contained fish, including capelin (82%), gadoids (64%), but that they also contained invertebrates including crabs (73%), clams (55%), snails (47%), amphipods (32%) and shrimps (18%). Adult males, females and juveniles all had a similar diet. Their large array of moustachial whiskers may be used in the manner of walruses to sort out the smaller food animals in their diet, which they may then suck up, also similarly to walruses (King, 183). However, they are generalized predators, also able to take pelagic schooling fish such as capelin (Antonelis et al, 1994).
Bearded seals are the largest of the northern phocids, with adults of both sexes measuring 2.1-2.4m and weighing 200-250kg (King, 1983). When pregnant and lactating females appear to be slightly larger and heavier than males (Burns, 1981; Fedoseev, 2000, Gjertz et al., 2000). Pups are on average 1.3m long and 34kg in weight at birth and about 1.47m long and 84kg at weaning (Burns, 1967; Gjertz et al., 2000). Females reach sexual maturity at about 6 years, males at 6-7 years (King, 1983). The life-span is recorded as about 25–30 years (Burns and Frost, 1979).