Arctocephalus forsteri | |
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Male | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Clade: | Pinnipedia |
Family: | Otariidae |
Genus: | Arctocephalus |
Species: | A. forsteri |
Binomial name | |
Arctocephalus forsteri Lesson, 1828 | |
Distribution of the New Zealand fur seal |
Arctocephalus forsteri (common names include the Australasian fur seal, [3] South Australian fur seal, [4] New Zealand fur seal, [5] Antipodean fur seal, or long-nosed fur seal) is a species of fur seal found mainly around southern Australia and New Zealand. [1] The name New Zealand fur seal is used by English speakers in New Zealand; kekeno is used in the Māori language. [6] [7] As of 2014 [update] , the common name long-nosed fur seal has been proposed for the population of seals inhabiting Australia. [1]
Although the Australian and New Zealand populations show some genetic differences, their morphologies are very similar, and thus they remain classed as a single species. After the arrival of humans in New Zealand, and particularly after the arrival of Europeans in Australia and New Zealand, hunting reduced the population to near-extinction. [1]
Males have been reported as large as 160 kg (350 lb); their average weight is about 126 kg (278 lb). [1] [8] Males can be 2 m (6 ft 7 in) long. Females are between 30 and 50 kg (66-110 lbs) on average, and can be as long as 1.5 m (4 ft 11 in). Newborn pups are 3.3–3.9 kg (7.3-8.6 lbs) on average, and between 40 and 55 cm (1.3-1.8 ft) long. At 290 days old males are about 14.1 kg (31 lb), and females are about 12.6 kg (28 lb). [1] Like other otariids, they have external ears and hind flippers that rotate forward, which visibly distinguish them from true seals. [6] They have a pointy nose with long pale whiskers. [6] Fur seals are covered by two layers of fur. The coat is grey-brown on their back, and lighter on their belly. [6] Some have white tips on longer upper hairs, which can give them a silver-like appearance. [6]
So called "Upland Seals" once found on Antipodes Islands and Macquarie Island have been claimed as a distinct subspecies with thicker furs by scientists although it is unclear whether these seals were genetically distinct. [9]
The species occurs in Australia and New Zealand. It is found in the coastal waters and on the offshore islands of southern Australia, from the south-west corner of Western Australia to just east of Kangaroo Island in South Australia, and also in southern Tasmania and the subantarctic Macquarie Island. Small populations are forming in Bass Strait and coastal waters of Victoria and New South Wales as far as the mid-north coast. Before the arrival of humans in New Zealand, the species bred around all the New Zealand mainland and its subantarctic islands. There are now established and expanding colonies around the entire South Island, on Stewart Island and all of the New Zealand subantarctic islands. There are also newly established breeding colonies on the North Island. [1]
The species can "porpoise" out of the water when travelling quickly at sea. [1] They can dive deeper and longer than any other fur seal. [6] Females can dive for about 9 minutes and to a depth of about 312 metres, and can dive deeper and longer in autumn and winter. Males can dive for about 15 minutes to a depth of about 380 metres. [1] On average, the species typically only dives for 1–2 minutes. [6] When they dive for food they dive deeper during the day but shallower at night, because during the day their prey typically migrates to deeper depths and migrates back up during the night (diel vertical migration). [6]
Lactating females alter their dive patterns in order to regularly care for their young. Dives are shorter, from around 9 minutes down to 5 minutes. Several longer trips may be taken at first to find patches of prey. The shorter dives then utilise these patches. Due to the differences in diving pattern between males and females, there is very little inter-sexual competition for food sources. Males typically forage over continental shelf breaks in deeper water, while females typically utilise the continental shelf as foraging grounds. It is believed that differences in diving abilities and depths could be the cause of some sexual dimorphism between males and females. [10]
Diving behaviour by the pups begins in the months leading up to weaning, when the pups are nursing less. The pups begin to dive from the age of 6–10 months, yet weaning is known to occur between the ages of 8 and 11 months, so the young pups do not have much time to learn to forage. The pups need to progressively develop nocturnal diving skills while they still have their mothers' milk to fall back on if dives are unsuccessful. Age, physiological development, and experience are important factors for success in hunting and contribute to the development of the pups' diving ability and behaviour. This transitional period, when young pups are becoming nutritionally independent while their foraging efficiency is rather low, is a time of high risk, and mortality can be very high. Based on scat samples, it has been found that the pups start by eating cephalopods and eventually making their way to fish, but this may just be a result of prey availability during different times of the year. [11]
Males vocalise through a bark or whimper, either a guttural threat, a low-intensity threat, a full threat, or a submissive call. Females growl and also have a high-pitched pup attraction wail call. [1] Pup-attraction calls allow communication from longer distances. Once together, females use olfactory recognition to confirm the pup as their own. [12] In males, the full neck display is a non-combative posture that functions as a threat to surrounding males by which they are able to assess each other's dominance status. [12]
Females mature between 4 and 6 years old, and males mature between 8 and 10 years old. [1] These seals are polygynous. [1] [6] Males obtain and guard territory in late October before females arrive. [1] Often females mate only once a year, and this usually occurs eight days postpartum for about 13 minutes on average. Females have a delayed implantation of the fertilised egg, so that implantation on the uterine wall does not occur for 3 months. [6] Gestation occurs for 9 months [6] Females are more aggressive near the time of birth, and do not like to be approached right after birth. [8] Females will continue to reproduce until their death which is on average between 14 and 17 years of age. [6]
Females first arrive on the shore between November and January, [1] just a few days before giving birth, and stay close to the birth site for up to ten days. When they are close to labour they become very restless and irritable. When beginning labour, which can last as much as five hours, they lie down and toss their head in the air, straining forward on their fore flippers, lifting their hind quarters, or moving laterally, before slowly lowering their head down, a process they repeat until they finally give birth. In one study, observations of the actual birth, starting from when the pup was first seen, found an average of 2 minutes for a head-first delivery, but an average of 6.5 minutes if the pup came out tail first. Immediately after birth the mother begins frequently sniffing the newborn pup to better identify when she has to find it after a trip out to sea. Pups are fairly mature at birth, and within 60 minutes they start suckling for about 7 minutes. Eventually the suckling can exceed 33 minutes. [8]
The mothers may take from 45 minutes to 3 days before leaving the pups to swim, and 6–12 days to go on longer feeding trips. Even then, the mothers tend to not leave the pups for longer than 2 days. When the pups are about 21 days old they have been seen to congregate into little pods while their mothers are away. When the females return they only feed their own pups, and have been seen to be hostile toward pups that are not their own. [13]
Female seals have been documented to have a gradual increase in trips for feeding throughout lactation. It has been found that mothers who have sons made longer foraging trips then the mothers who had daughters during the lactation period. When observing growth patterns in the male and female pups within two cohorts, it is recognised that the growth patterns are similar, however the males grow faster and are weaned off nursing heavier in some years. [14] Suckling can occur for about 300 days. Pups start to eat solid food just before weaning, [6] and are eventually weaned around September, when they disperse. [8] [6]
Pup mortality has been attributed to both natural factors and human interaction. The biggest natural cause of death for pups is starvation, followed by suffocation in the amnion, stillbirth, trampling, drowning, and predation. [15] Human factors include the handling of pups, tagging, and human presence in general. [15]
Their diet includes cephalopods, fish, and birds. [1] In New Zealand, New Zealand octopus and arrow squid make up most of their cephalopod diet. [16] Individuals located near their southern range limit have been known to eat penguins as part of their diet. [16] Stomach contents have been analysed and shown to include Australian anchovy, barracouta, Paralichthyes flounders, broadgilled hagfish, pouched lamprey, red cod, school shark, and many other species. [17] Further analysis of otoliths from their scat show that for fish prey species, lanternfishes composed the majority of their fish diet, followed by Australian anchovies, ahuru, and hoki. [16] There are different factors that affect their diet, such as season, sex, breeding, surrounding colony, oceanography, and climatic patterns. [17]
Known predators are killer whales, sharks, male New Zealand sea lions, and possibly leopard seals. [1] New Zealand sea lions are also known to target pups as their prey. [18] Several regurgitations by sea lions have been found to contain remains of fur seal pups, some with plastic tags previously attached to female fur seal pups. [18]
Before the arrival of humans, the seals bred around all of New Zealand. Hunting by the first New Zealand settlers, the Māori, reduced their range. Commercial hunting from shortly after the European discovery of New Zealand in the 18th century until the late 19th century reduced the population near to extinction.
Today, commercial fisheries are one of the main causes of death in New Zealand fur seals, usually by entanglement and drowning. [1] Monitoring of these pinnipeds in the Kaikōura region found that entanglements with green trawl nets and plastic strapping tape were the most common. [19] A little less than half of the individuals were successfully released with good chances of survival even after significant entanglement wounds. [19] It has been estimated by the Royal Forest and Bird Protection Society that over 10,000 seals could have drowned in nets between 1989 and 1998. [8] They are also known to have been shot by commercial and recreational fishermen, because they are assumed to interfere with fishing gear. How often these shootings occur is unknown, but pressure groups have stated that the conflict between the seals and commercial fisheries is expected to increase. [20] On 21 August 2014, two decomposing animals were found beheaded near Louth Bay in South Australia. The circumstances of their deaths were considered suspicious and an investigation followed their discovery. [21] In 2015, several conservative members of Parliament encouraged public debate around the potential implementation of seal culling in South Australia in response to increasing interactions with South Australian commercial fisheries. As of July 2015 [update] , the killing of long-nosed fur seals remains an illegal act.
Human activity near seal rookeries has been correlated with distress and panic, resulting in indirect deaths of pups. [15] The use of metal cattle ear tags on pups has also been associated with a decrease in pup fitness due to incomplete healing of the tag site. [15]
In Australian Commonwealth waters, Arctocephalus forsteri is protected under the Environment Protection Biodiversity Conservation (EPBC) Act 1999, under which it is listed as a protected marine species. [22] The species is also protected within the jurisdictions of the following Australian states:
State | Listed as | Legislation |
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New South Wales | Vulnerable | Threatened Species Conservation Act 1995 (NSW) [22] |
South Australia | Marine mammal | National Parks and Wildlife Act 1972 (SA) [23] |
Tasmania | Rare | Threatened Species Protection Act 1995 (TAS) [22] |
Victoria | Protected | Wildlife Act 1975 (Vic) [24] |
Western Australia | Other protected fauna | Wildlife Conservation Act 1950 (WA) [22] |
The species received protection by the creation of the 16 million hectare Macquarie Island Marine Park, located on the eastern side of Macquarie island. In 2000, the Tasmanian government extended the Macquarie Island Nature Reserve by 3 nautical miles surrounding the island. [25]
In New Zealand, the species is protected by the Marine Mammals Protection Act 1978 , which works to conserve marine animal species; it specifies that all wild pinnipeds cannot be touched or fed. [1]
Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively long and muscular foreflippers, and the ability to walk on all fours. They are marked by their dense underfur, which made them a long-time object of commercial hunting. Eight species belong to the genus Arctocephalus and are found primarily in the Southern Hemisphere, while a ninth species also sometimes called fur seal, the Northern fur seal, belongs to a different genus and inhabits the North Pacific. The fur seals in Arctocephalus are more closely related to sea lions than they are to the Northern fur seal, but all three groups are more closely related to each other than they are to true seals.
An eared seal, otariid, or otary is any member of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant species in seven genera and are commonly known either as sea lions or fur seals, distinct from true seals (phocids) and the walrus (odobenids). Otariids are adapted to a semiaquatic lifestyle, feeding and migrating in the water, but breeding and resting on land or ice. They reside in subpolar, temperate, and equatorial waters throughout the Pacific and Southern Oceans, the southern Indian, and Atlantic Oceans. They are conspicuously absent in the north Atlantic.
Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. The sea lions have six extant and one extinct species in five genera. Their range extends from the subarctic to tropical waters of the global ocean in both the Northern and Southern Hemispheres, with the notable exception of the northern Atlantic Ocean. They have an average lifespan of 20–30 years. A male California sea lion weighs on average about 300 kg (660 lb) and is about 2.4 m (8 ft) long, while the female sea lion weighs 100 kg (220 lb) and is 1.8 m (6 ft) long. The largest sea lions are Steller's sea lions, which can weigh 1,000 kg (2,200 lb) and grow to a length of 3.0 m (10 ft). Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight at a single feeding. Sea lions can move around 16 knots in water and at their fastest they can reach a speed of about 30 knots. Three species, the Australian sea lion, the Galápagos sea lion and the New Zealand sea lion, are listed as endangered.
Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semi-aquatic, mostly marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae, with 34 extant species and more than 50 extinct species described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the suborder Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.
The Baikal seal, Lake Baikal seal or nerpa is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada,, as well as the Saimaa ringed seal and the Ladoga seal, are also found in fresh water, but these seals are part of species that also have marine populations.
The leopard seal, also referred to as the sea leopard, is the second largest species of seal in the Antarctic. Its only natural predator is the orca. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, fish, and birds, particularly penguins. It is the only species in the genus Hydrurga. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals. The name hydrurga means "water worker" and leptonyx is the Greek for "thin-clawed".
The northern elephant seal is one of two species of elephant seal. It is a member of the family Phocidae. Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. Sexual dimorphism in size is great. Correspondingly, the mating system is highly polygynous; a successful male is able to impregnate up to 50 females in one season.
Elephant seals or sea elephants are very large, oceangoing earless seals in the genus Mirounga. Both species, the northern elephant seal and the southern elephant seal, were hunted to the brink of extinction for oil by the end of the 19th century, but their numbers have since recovered. They are the largest extant carnivorans, weighing up to 4,000 kilograms (8,800 lb). Despite their name, elephant seals are not closely related to elephants, and the large proboscis or trunk that males have was convergently evolved.
The harp seal, also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.
The northern fur seal is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only living species in the genus Callorhinus. A single fossil species, Callorhinus gilmorei, is known from the Pliocene of Japan and western North America.
The Antarctic fur seal is one of eight seals in the genus Arctocephalus, and one of nine fur seals in the subfamily Arctocephalinae. Despite what its name suggests, the Antarctic fur seal is mostly distributed in Subantarctic islands and its scientific name is thought to have come from the German vessel SMS Gazelle, which was the first to collect specimens of this species from Kerguelen Islands.
The subantarctic fur seal is a species of arctocephaline found in the southern parts of the Indian, Pacific, and Atlantic Oceans. It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate specific name tropicalis.
The Guadalupe fur seal is one of eight members of the fur seal genus Arctocephalus. They are the northernmost member of this genus. Sealers reduced the population to just a few dozen by the late 19th century, but the species had recovered to 10,000 in number by the late 1990s. Many individuals can be found on Mexico's Guadalupe Island.
The Juan Fernández fur seal is the second smallest of the fur seals, second only to the Galápagos fur seal. They are found only on the Pacific Coast of South America, more specifically on the Juan Fernández Islands and the Desventuradas Islands. There is still much that is unknown about this species. Scientists still do not know the average life span of this species, or the diet and behavior of males apart from the breeding season.
The Galápagos fur seal is one of eight seals in the genus Arctocephalus and one of nine seals in the subfamily Arctocephalinae. It is the smallest of all of the eared seals. They are endemic to the Galápagos Islands in the eastern Pacific. The total estimated population as of 1970 was said to be about 30,000, although the population has been said to be on the decline since the 1980s due to environmental factors such as pollution, disease, invasive species, and their limited territory. Due to the population having been historically vulnerable to hunting, the Galápagos fur seal has been protected by the Ecuadorian government since 1934
The brown fur seal, also known as the Cape fur seal, South African fur seal and Australian fur seal, is a species of fur seal.
The Australian sea lion, also known as the Australian sea-lion or Australian sealion, is a species of sea lion that is the only endemic pinniped in Australia. It is currently monotypic in the genus Neophoca, with the extinct Pleistocene New Zealand sea lion Neophoca palatina the only known congener. With a population estimated at 14,730 animals, the Wildlife Conservation Act of Western Australia (1950) has listed them as “in need of special protection”. Their Conservation status is listed as endangered. These pinnipeds are specifically known for their abnormal breeding cycles, which are varied between a 5-month breeding cycle and a 17-18 month aseasonal breeding cycle, compared to other pinnipeds which fit into a 12-month reproductive cycle. Females are either silver or fawn with a cream underbelly and males are dark brown with a yellow mane and are bigger than the females.
The South American fur seal breeds on the coasts of Peru, Chile, the Falkland Islands, Argentina, Uruguay and Brazil. The total population is around 250,000. However, population counts are sparse and outdated. Although Uruguay has long been considered to be the largest population of South American fur seals, recent census data indicates that the largest breeding population of A. a. australis are at the Falkland Islands followed by Uruguay. The population of South American fur seals in 1999 was estimated at 390,000, a drop from a 1987 estimate of 500,000 - however a paucity of population data, combined with inconsistent census methods, makes it difficult to interpret global population trends.
The Weddell seal is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing captain James Weddell to the area of the Southern Ocean now known as the Weddell Sea. The life history of this species is well documented since it occupies fast ice environments close to the Antarctic continent and often adjacent to Antarctic bases. It is the only species in the genus Leptonychotes.
The southern elephant seal is one of two species of elephant seals. It is the largest member of the clade Pinnipedia and the order Carnivora, as well as the largest extant marine mammal that is not a cetacean. It gets its name from its massive size and the large proboscis of the adult male, which is used to produce very loud roars, especially during the breeding season. A bull southern elephant seal is about 40% heavier than a male northern elephant seal, which is nearly twice the weight of a male walrus, or 6–7 times heavier than the largest living mostly terrestrial carnivorans, the Kodiak bear and the polar bear.