Seal skins and oil were among the first of New Zealand's natural resources to appear in world markets. The early enterprises of sealers, here as elsewhere, were conducted in secrecy; consequently the records are few. But it seems probable that commercial sealers first hunted in New Zealand waters about 1792. The industry flourished briefly; in less than 30 years the seals were hunted almost to extinction both in New Zealand and in the sub-Antarctic islands. Only in recent years have they been allowed, under legal protection, to increase in numbers and approach their former population strength.
By modern systematists, seals are grouped in the order Pinnipedia, although some biologists would still prefer to regard them as aquatic members of the order Carnivora. Superficially, they are remarkably doglike, and the pups of many species bark as though to claim affinities with the dogs. Seals are, however, considerably modified both internally and externally for life in the sea. Their limbs are paddles, their shape is streamlined, and their blood system, muscles, and skin show many adaptations which help them to dive and swim efficiently. Under water the heart slows to a rate of three to six beats per minute. Some seals, possibly all, have a muscular collar on the diaphragm which constricts their blood system, so that circulation is maintained only in the vessels of the head during a dive; the muscles of viscera and limbs work under anaerobic conditions, and thus all available oxygen is reserved for the brain. Seals have more blood than do land animals of similar size, and so take down considerable stores of oxygen when they dive.
Most seals live in cold water, where food is plentiful; New Zealand is toward the northern edge of the range where seals would be expected, although tropical and subtropical species are known. Living in waters colder than their own bodies, they require insulation to prevent excessive heat loss; hence the thick blubber, hide, and fur which attracted the sealing gangs of the eighteenth and nineteenth centuries. Fur is found only on sub-Antarctic animals, together with comparatively thin blubber; in climates where icing might become a problem seals have a much thinner covering of hair, without the dense under-pelt which furriers value, and insulation is maintained by a much thicker layer of blubber. On the sub-Antarctic islands of New Zealand both fur-yielding and oil-yielding species were found; in New Zealand itself only fur seals were of any commercial importance, although it is possible that sea lions (which yield oil and hides) may also have been taken at one time from the west coast of the South Island.
Biologically, seals are divided into three families of which one (Odobenidae, the walruses) is found only in the Northern Hemisphere. The remaining families, Otariidae, the eared seals (including fur seals and sea lions), and Phocidae, the so-called “true seals”, have a world-wide distribution, with a tendency to congregate in the colder waters of high-latitude seas and polar currents. Three species of seals breed at present in the New Zealand region (including the sub-Antarctic islands): two are eared seals, and the third is the largest of the true or Phocid seals, the sea elephant. Only one species, the New Zealand fur seal Arctocephalus forsteri, breeds north of the forty-eighth parallel in the South Island; the other two are entirely sub-Antarctic in range and are seldom seen even as stragglers on the main islands of New Zealand.
The New Zealand fur seal is peculiar to this country, although very similar to a closely related form inhabiting southern Australia and Tasmania. Little research has been done and the true status, habits, food, and numbers of the New Zealand fur seal are almost unknown. It appears at present to be thriving and increasing. Two small breeding colonies are known in the South Island, and several non-breeding accumulations of animals are reported; larger breeding colonies are known on the Chatham, Snares, and Auckland Islands, and breeding may also occur on Campbell and Macquarie Islands. Population may number from 40,000 to 50,000. Mature bulls are between 6 and 7 ft long. Cows and young bulls seldom exceed 5ft. The fur is grey-brown, with a dense buff, stone-coloured, or reddish under-pelt; nose and flippers are dark brown shading to black. The tiny pointed ears, almost hidden among the head fur, and the forward-pointing hind flippers are diagnostic of the family Otariidae to which this species belongs. The rich fur, sharply pointed muzzle, and swept-back whiskers distinguish it from the sea lion, which it otherwise resembles in shape and character. Fur seals are most characteristically seen on rocky headlands and reefs, where they drape themselves in seemingly comfortless positions for sleep. Quarrelsome and aggressive amongst themselves, they are uneasy in the presence of man and usually move back into the sea when he approaches. In the water their powerful shoulders and foreflippers propel them with speed and great manoeuvrability; the hind feet, which are used much in walking over the rocks, play a lesser role when the animals are swimming.
The sea lion of New Zealand's sub-Antarctic, Hooker's sea lion Phocarctos hookeri, was named after the botanist of Ross's naval survey expedition which first brought specimens back for scientific study. This animal breeds in large colonies at Carnley Harbour and Enderby Island, in the Auckland Islands group. A few breed on Campbell Island, and larger groups of non-breeding adults are reported from the Snares and other sub-Antarctic islands. Sea lions are generally larger and heavier than fur seals; large males measure up to 10 ft and have a characteristic “mane”; mature females range from 5 to 7 ft in length. They lack the dense underpelt which fur seals have; their hide was, however, tanned and used as a strong, supple leather for clothing. Hooker's sea lion is grey or fawn, fading to white; the species is peculiar to the New Zealand area, although closely related to similar animals on other islands in the southern oceans. Little is known of its habits or numbers.
Elephant seals or sea elephants (so called from the large, inflatable proboscis of the males during the breeding season) are found throughout the sub-Antarctic islands of the Atlantic, Indian, and Pacific Oceans. In the New Zealand region they breed in large concentrations on Campbell and Macquarie Islands, and in 1949 a small breeding colony was reported to have formed on the Antipodes Islands. The largest bulls of this species reach lengths of 20 ft or more; cows are seldom longer than 10 ft. The hair is coarse and short. Old bulls are often heavily scarred from fighting and lose much of the hair from their neck and face. Their colour is buff or brown, but may vary from silver grey to fawn in younger animals; cows and young bulls are similar in shape and colour, and the distinctive inflatable proboscis of the mature bull appears only in the sixth or seventh year. Like all other Phocids, elephant seals lack external ears. Their hind limbs trail backward both in walking and in swimming; the forelimbs are reduced in comparison with those of the Otariidae, and the animals move by undulating the muscles of the trunk. The species has recently been made the subject of an intensive study by Australian biologists on Macquarie Island (see papers by Carrick and others in CSIRO Wildlife Research 7 (2), 1962).
The breeding habits of the three New Zealand species of seals are very similar. Early in the breeding season, about October or November, the large bulls haul out of the water and take up territories along beaches and rocky shores. Each defends its area against incursion by neighbours and fights off younger bulls which attempt to carve out territories of their own. Three to five weeks later the cows begin to arrive, forming groups or harems of 10 to 15 within the territories. The old bulls defend their harems against the attentions of the younger bulls, rounding up the straying cows and fighting intruders almost continuously throughout the summer, with considerable expenditure of energy. They live only on their reserves of fat during the breeding season which may extend over three months or more.
The cows give birth to their pups shortly after leaving the water, and usually mate within a few days or weeks of parturition. The fertilised egg of the elephant seal (probably also of the other species) remains unattached in the uterus for several weeks before implanting, so that development begins late in summer, and the foetus, with a true gestation period of nine to 10 months, is ready for birth 11 to 12 months after fertilisation. The pup of the elephant seal weighs about 100 lb at birth and measures slightly over 4 ft from nose to tail. Its birth weight doubles in 11 days (the human infant doubles its birth weight in six months), and the mother ceases to feed the pup after three to four weeks. Its downy birth coat is shed rapidly during the first week of life (or may even be lost before it is born), and the pup is ready for the sea at an age of six to eight weeks. Fur seals and sea lions keep their young by them for several months; the pups apparently grow more slowly and take longer to reach independence.
Other species of seals visit New Zealand from time to time; most frequently reported are young sea leopards (Hydrurga leptonyx) and Weddell seals (Leptonychotes weddelli) from the Antarctic. Sea leopards are also seen often about the sub-Antarctic islands.
Seals were first reported in New Zealand by Captain Cook who found in Dusky Sound “great numbers, about the bay, on the small rocks and isles near the sea coast”. In 1792–93, 19 years after Cook's discovery, a party of sealers spent 10 months in the Sound, securing 4,500 seals which they skinned for the China market. Sealing later spread to islands in Foveaux Strait, to Stewart Island, and to the deep harbours of the west coast. During the early period, when southern New Zealand was the centre of interest, most of the sealers came from Australian ports; in 1804 American vessels were first reported in the trade, with the sub-Antarctic islands as their goal. About that year some 60,000 skins were taken from Antipodes Island, and, during the following decade, the Bounty, Auckland, Chatham, Macquarie, and Campbell Islands were in turn visited and divested of their seals. Fur seals were usually the first to be taken, but oiling parties with their trypots and barrels followed closely to make use of the elephant seals and sea lions. After 1813 most of the trade was centred on Macquarie Island, where oiling alone remained profitable; on the South Island and elsewhere in the sub-Antarctic islands only sporadic visits were made to clear up remnants of the stock as a source of profit incidental to other forms of trading.
The hardships of the sealers have been recounted in many authentic records; the occupation was undoubtedly hazardous, and probably with little reward to those who saw it at first hand. Parties left for a season or a year on remote islands were often forgotten or abandoned by accident; one group was left on the bare and waterless Bounty Islands for a year, and parties survived on the Solanders for five years, and on the Snares for seven years, according to contemporary accounts. Sealing ventures continued throughout the nineteenth century, realising only very small quantities of skins and oil, and ceased with the protection of all species early in the present century. Although protection has from time to time been withdrawn from fur seals, to prevent an increase in their numbers, there is little chance of the species becoming economically important in the near future.
by Bernard Stonehouse, B.SC.(LOND.), M.A., D.PHIL.(OXON.), Reader in Zoology, University of Canterbury.