Arctocephalus forsteri

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New Zealand fur seal
Seal 0906.jpg
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Pinnipedia
Family: Otariidae
Subfamily: Arctocephalinae
Genus: Arctocephalus
Species: A. forsteri
Binomial name
Arctocephalus forsteri
Lesson, 1828
Arctocephalus forsteri distribution.png
Distribution of the New Zealand fur seal

Arctocephalus forsteri, also known as the New Zealand fur seal or southern fur seal, is a species of fur seal found around the south coast of Australia, the coast of the South Island of New Zealand, and some of the small islands to the south and east of there.[1] Male-only colonies are also located on the Cook Strait coast of the North Island near Wellington and vagrants are found as far north as New Caledonia.[citation needed] The English common name New Zealand fur seal is used by English speakers in New Zealand (kekeno is used in the Māori language), and southern fur seal by English speakers in Australia.[citation needed] Although the two populations show some genetic differences, their morphologies are very similar, and thus they remain classed as a single species.[1]

Although the seals look docile, they can move surprisingly quickly and it is advisable never to approach a female with young or get between a seal and the water, cutting off its escape route to the sea.

Physical Characteristics[edit]

The New Zealand fur seal is a fairly large mammal. Males have been reported to be as large as 250 kg in the literature, but the average weight is about 126 kg.[1][2] Males can also grow to be 2 meters long. Females are between 30–50 kg on average, and can grow to be as long as 1.5 meters. Pups are 3.3-3.9 kg on average, and between 40 and 55 cm long. At 290 days old males are about 14.1 kg, and females are about 12.6 kg.[1] They have external ears and hind flippers that rotate forward, which visibly distinguish them from other seals.[3] They have a pointy nose with long pale whiskers.[3] The fur seals are covered by two layers of fur, and their coat is grey-brown on their back, but it is lighter on their belly.[3] Some fur seals have white tips on longer upper hairs, which can give the fur seal a silver like appearance.[3]

Behavioral Characteristics[edit]

Diving[edit]

New Zealand fur seals "porpoise" out of the water when traveling quickly at sea.[1] New Zealand fur seals are the best at diving out of any other fur seal because they can dive deeper and longer.[3] Females can dive for about 9 minutes and to a depth of about 312 meters. But females can dive deeper and longer in autumn and winter. Males can dive for about 15 minutes to a depth of about 380 meters.[1] On average New Zealand fur seals only dive for 1–2 minutes.[3] 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.[3]

Communication[edit]

Males vocalize through a bark or whimper, either a gluttural 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]

Breeding[edit]

Female New Zealand fur seals mature between 4 and 6 years old, and males mature between 8 and 10 years old.[1] These seals are polygynous.[1][3] Males obtain and guard territory in late October before females arrive.[1] Often females only mate once a year, and this usually occurs eight days postpartum for about 13 minutes on average. Females have a delayed implantation of the fertilized egg, so that implantation on the uterine wall does not occur for 3 months.[3] Gestation occurs for 9 months[3] Females are more aggressive near the time of birth, and do not like to be approached right after birth.[2] Female New Zealand fur seals will continue to reproduce until their death which is on average between 14 and 17 years of age.[3]

Parenting[edit]

Pups are born between November and January.[1] Females stay close to the birth site for up to ten days. Pups are fairly mature at birth, and within 60 minutes they start suckling for about 7 minutes. Eventually the suckling can exceed 33 minutes.[2] Suckling can occur for about 300 days. Pups start to eat solid food just before weaning.[3] Pups are eventually weaned around September, and they disperse.[2][3]

Diet[edit]

Their diet includes cephalopods, fish, and birds.[1] Stomach contents have been analyzed and shown to include anchovy, barracuda, flounder, hagfish, lamprey, red cod, school shark, and many other species.[4] There are different factors that affect their diet, such as season, sex, breeding, surrounding colony, oceanography, and climatic patterns.[4]

Predators[edit]

New Zealand fur seals’ 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.[5]

Human Impact[edit]

These seals were widely hunted from shortly after the European discovery of New Zealand until the late 19th century. The population of the New Zealand seal fell to levels under 10% of the original numbers. Today trawls and fisheries are one of the main sources of death in New Zealand fur seals. They cause entanglement and drowning.[1] It has been estimated by the Royal Forest and Bird Protection Society that over 10000 seals could have drowned in nets between 1989 and 1998.[2] They are also known to be shot by commercial and recreational fishermen, because they sometimes interfere with fishing gear. How often these shootings occur is unknown, but the conflict between the seals and commercial fisheries is expected to increase.[6] New Zealand fur seals have recently received protection by the creation of a 16 million hectare Marine Park that is located on the eastern side of Macquarie island in 2000. The Tasmanian government has also extended to Macquarie Island Nature Reserve by 3 nautical miles surrounding the island.[6] New Zealand fur seals are protected by the Marine mammals protection act of 1978, which works to conserve marine animal species.[1]

Gallery[edit]

References[edit]

  1. ^ a b c d e f g h i j k l m n o p Goldsworthy, S. & Gales, N. (IUCN SSC Pinniped Specialist Group) (2008). Arctocephalus forsteri. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 14 January 2009.
  2. ^ a b c d e Harcourt, R.G., (2001). "Advances in New Zealand mammalogy 1990-2000: Pinnipeds" "Journal of The Royal Society of New Zealand", Downloaded October 6, 2011
  3. ^ a b c d e f g h i j k l m Department of Conservation. "New Zealand fur seal/kekeno" Found October 6, 2011
  4. ^ a b Boren, L. (2010) "Diet of New Zealand fur seals (Arctocephalus forsteri): a summary", Downloaded October 6, 2011
  5. ^ Bradshaw, C.J.A., Lalas, C., & McConkey, S. (1998). “New Zealand sea lion predation on New Zealand fur seals” “New Zealand Journal of Marine and Freshwater Research”, Downloaded October 6, 2011
  6. ^ a b MarineBio.org (2011). "New Zealand Fur Seals, Arctocephalus forsteri at MarineBio.org" Found October 6, 2011

Sources[edit]

  • Randall R. Reeves, Brent S. Stewart, Phillip J. Clapham and James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0375411410. 

External links[edit]