Arctocephalus forsteri

Geographic Range

New Zealand fur seals ( Arctocephalus forsteri ) are a non-migratory coastal species. Prior to being driven to near extinction, the population was historically found all around the North and South Islands including many offshore islands and sub-Antarctic islands. Today, they are found in New Zealand, around South Island, Big Green Island, Open Bay Islands, West Coast, Cape Foulwind, Cascade Point, Wekakura Point, Three Kings Islands, eastern Bass Strait, the Nelson-northern Marlborough region, Fjordland, New Zealand's sub-Antarctic islands Snares, Campbell, Chatham Islands, Antipodes, Bounty Islands, Stewart Island, the islands of the Foveaux Strait, a small colony at Cape Palliser near Wellington on the North Island and near the continental shelf edge of Otago Peninsula. There is also a population in southern and western Australia, Kangaroo Island, Tasmania and Victorian coastal waters, although the two New Zealand and Australian populations rarely overlap. On Australia’s sub-Antarctic Macquarie Island, a population of young non-breeding males was discovered. They are believed to have originated from New Zealand. The distribution of seals across this range is largely a result of the distribution of their food source. When New Zealand fur seals migrate it’s during the breeding season. However, during the summer, they stay closer to the rookery (70 to 80 km) then they do during the fall and winter seasons (162 to 178 km).

• Biogeographic Regions
• australian australian
  • native native
• oceanic islands oceanic islands
  • native native
• indian ocean
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

The New Zealand fur seals often inhabit rocky coastlines and offshore islands that provide protection from the strong ocean waves. They seem to prefer beaches with large rocks, reefs just off the coast and smooth rocky ledges to gain easy access to the sea. Warmer islands tend to have rock pools that the seals use for cooling. Areas of vegetation that contain tussock and scrub are the usual sanctuaries of breeding seals and their young. Non-breeding colonies are more flexible in their choice of habitat Females are mid-water feeders with the distance and depth depending on the season and the age of their pups. During the breeding season, they will feed just beyond the continental shelf. During the fall and winter seasons, they will venture out for longer periods of time and dive further depths. Adult males feed over the continental slope and the juvenile seals forage in areas specifically containing the migrating lanternfish . Both the adult males and females will forage in shallow waters (0 to 20 m), but most often do benthic dives off the continental slope (females 60 to 80 m and males 100 to 200 m). The longest dive and deepest depth recorded for the females are 9.3 minutes and 312 m, whereas for males they are 14.8 minutes and 380 m.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• saltwater or marine saltwater or marine

• Aquatic Biomes
• reef reef
• coastal coastal

Physical Description

New Zealand fur seals have a pointed nose, long whiskers and ear flaps. The adult coat consists of two layers, a topcoat that is a dark grey-brown on the dorsal side, which gradually lightens to a lighter gray-brown underside, provides a sense of camouflage, and a thick undercoat. Seals dark appearances comes from their deep chestnut undercoat and the dark gray coarse guard hairs of the topcoat. When the fur is wet, it appears darker, but when it is dry the white tipped guard hairs give off a silvery sheen. At five months, the pups shed their black coats for their more adult silvery-grey coats. The bulls have long, thick guard hairs that make up their coarse mane. The females do not develop this mane. New Zealand fur seals are sexually dimorphic. The males are three times the females’ weight and 1.3 times longer. Bulls are massive throughout their neck and shoulders, while females possess an overall slender physique. Even male pups are significantly larger than female pups, which is due the high lipid reserves of female pups, while the male pups consist of more lean muscle tissue. Adult males average 1.5 to 2.5 m long and weigh 120 to 180 kg. Adult females average 1 to 1.5 m long and 30 to 50 kg. The largest male on record weighed 250 kg and the largest female weighed 90 kg. Physically there are no differences between the New Zealand fur seal and the Australian fur seal . Only genetic differences distinguish them.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes shaped differently

Reproduction

New Zealand fur seals have a polygynous system, in which the male defends his territory with his harem of 5 to 8 females. As an island-hopper, a male fur seal will choose an island as his breeding site. When they arrive at an island, males will compete with each other to establish their territories a full two weeks before pregnant females come ashore. Successful males with established territories are typically those between 7 and 15 years of age. Both male and female seals that aren’t breeding find other hauling grounds to rest upon during that season. The ideal territory has many shaded areas for the male and his group of females to cool themselves. These sheltered areas near the sea are frequently fought over throughout the breeding season and seldom left unoccupied by the territory holder. Seals appear on the hauling grounds, which allow easy access to and from the sea, around late October and stay until at least early February. As the breeding season progresses and the number of territorial males increases, the size of an individual’s territory decreases. Most communication during the breeding season is aggressive. The males will herd the females to keep them on their territory and away from the other males. The longer the female is on a male’s territory, the higher the chances are that she will mate with him. Each male performs his herding techniques slightly different from the others. Females are allowed to move about the hauling grounds, but the herding territorial males make it difficult by blocking access for up to an hour at times. Smelling is another key part of their mating behaviors. Males will smell the face and perineal regions of females to determine if the female is ready to mate. If the female is not ready to receive the male she displays aggressive behaviors such as growling, snapping and moving away. Females become more aggressive right before and after birth. Around eight days after giving birth, the female again goes into estrous. When the female is in estrous she will show interest in the male who occupies the territory she gave birth in by rubbing up against him and displaying very little aggression. The male detects the female’s sexual readiness by olfaction primarily. Copulation consists of mutual touching, and the male mounting and biting. When the female begins to the resist the male, he soon ejaculates and dismounts the female. The entire copulation can take from 5 to 30 minutes.

• Mating System
• polygynous polygynous

The breeding season for the New Zealand fur seal starts in late October and ends by early February. To increase breeding opportunities, males will remain ashore for as long as possible, surviving off energy reserves. The male will not eat for two to three months of breeding season. Cows typically mate once a year and have a gestation period of nine months. After fertilization the embryo goes through a 2 to 4 month delayed implantation. This allows females to birth and mate in the same breeding season. It also allows her body recovery time between birthing and the development of her next pup. The pups are born between late November and mid-January, with an average length of 40 to 55 cm. These pups are precocial, and can start suckling within 60 minutes. At 9 to 10 months of age the pups are weaned. There is significant weight variation in the pups at birth, which may be explained by the considerable sexual dimorphism between the two sexes. Male pups weigh on average 3.9 to 5.6 kg at birth and females at birth weigh 3.3 to 4.8 kg. At 290 days old the male pups weighed 14.1 kg and the females were 12.6 kg. From birth to 240 days of age the pups gained on average 24 g and 0.86 cm a day, but this rate slowed as they continued to age. Both male and female New Zealand fur seals reach sexual maturity around four to five years of age. Females will deliver their first pup at this time, but males don’t become territorial until 8 to 10 years because their body size does not compete with other males. Seven to eight days after giving birth, the cows will mate with the bull closest to her. Usually this will end up being the bull in whose territory they reside. Females breed anytime throughout the breeding season. However, only females breeding for the first time or females that didn't birth and rear a pup the year before are early season breeders.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous
• delayed implantation delayed implantation

When New Zealand fur seal cows have have pups they protect and nurse it. Six to twelve days after giving birth, cows will leave their pup with other pups and start the feeding/weaning cycle. Mothers will go to sea and feed for three to eight days before returning to their pup and let it suckle for two to seven days. As the pup gets older, the foraging trips the cow takes gradually become longer and her time ashore becomes shorter. Harems occur when multiple females loyal to territorial bulls return to the bull’s territory. When several of the mothers simultaneously leave their pups for longer periods on feeding trips, the pups gather into small groups called pods until each hears the call of its mother and returns to her to suckle. The older the pups get, the more adventurous they become. They swim in water pools, play with the other pups, and mimic battles. The birth mass of the pup is related to the changes in yearly conditions such as place of birth, the mother’s age, her experience, prey abundance, and the mother’s foraging efficiency.

• Parental Investment
• precocial precocial
• female parental care female parental care
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

In the wild, the oldest observed New Zealand fur seals were a 25 year-old female and a 19-year-old male. The average lifespan in the wild is assumed to be 15 years for a male and 12 years for a female. However, the first year is the hardest - during the first 300 days, pup mortality is approximately 40%. The only captive age recorded was 23.1 years.

Behavior

Outside of the breeding season males will practice comfort behaviors such as scratching, rubbing and grooming for long periods of time. They are able to perform these comfort behaviors with their teeth, wrists of the fore flippers and their nails on their hind flippers. They will even rub up against jagged rocks to get the places on their body they otherwise couldn’t reach. Grooming behaviors are most often seen after the seal hauls themselves on to the shore from the water. When the days are cold, fur seals are found sleeping on land with their flippers tucked under them and their bodies slightly curled up to retain heat. The New Zealand fur seal’s body is built with a high amount fat storage for insulation so cold weather is rarely a problem. On warmer days the fur seals will lay with their body and fins extended for maximum heat loss. In mid-summer the fur seal’s frequency of movement slows down. They will seek out shade, pools of water, or will take dips into the sea. New Zealand fur seals primarily swim, but they move on shore with clumsy, awkward movements. Pups are capable of swimming at birth, but they spend their time practicing and building confidence when their mother is away on feeding trips. During the weaning period they also practice fishing in calm intertidal pools. At nine months, when the pups have reached independence, they will run to hide in the ocean instead of rock crevices. If an adult New Zealand fur seal becomes frightened, he runs to the sea and the entire herd follows. They will swim out a few meters before they will look back to examine the intruder. Pups, on the other hand, are curious and will venture toward shore before the rest of the herd.

• Key Behaviors
• terricolous
• natatorial natatorial
• diurnal diurnal
• motile motile
• nomadic nomadic
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

Males form territories is during the breeding season. At its peak, the territory rarely exceeds 100 square meters. Juvenile seals and non-breeding adults generally stay away from the breeding grounds and choose the less ideal rocky hauling grounds during this season.

Communication and Perception

New Zealand fur seals communicate through posture and physical movement. Territory boundaries and readiness to fight can be recognized through these actions. Status of males can be assessed and established by the full neck display, where the smaller-necked males avoid the confrontation. The full neck posture is described as sitting in an upright, vertical position. The chest is protruding out, head is tilted back and nose is pointed up towards the sky. If the two males are the same size, the full neck display is done for much longer where the male’s chests keep in contact with the other. In order to prolong the display, while maneuvering for an attack position neck waving is conducted. When they carry their neck and head low dipped position, it’s to indicate submission; either after losing a full neck display or to avoid a fight in general. The male seal that has lost the full neck display faces away to appease the winner. The alert posture shows general awareness, where an open-mouth display is used as an aggressive and a submissive display. Young pups have also been seen doing these displays during play-fighting with one another, however as the pups get older, they are more aggressive and skilled.

New Zealand fur seals also produce vocalizations, to give low intensity threatening calls. Territorial males will often bark to demonstrate their status or give a loud, deep, throaty, gruff call known as a choke call. The bark can also show sexual interest, where both males and females will whine or squeal to be more submissive. Male fur seals also whine or squeal to appease the winning male after a fight, while females threaten others by producing a high-pitched raspy growl. When a female needs to locate her pup she uses both vocalization and vision. Once the female leaves the water she holds her body upright, extends and arches her head and neck forward searching, producing a high-pitched, rising screech. The returned call from the pup is also a high-pitched screech, but more monotone. To confirm recognition the female uses her olfactory senses to either accept or reject the pup as they sniff each other’s faces and noses. The seal’s whiskers are useful in sensing, underwater vibrations and therefore locate food.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

The New Zealand fur seals are opportunistic foragers and will vary their diet according to what is available in the season and their location. They prey on several different cephalopods, fish, and birds throughout the year. The New Zealand fur seals can use their whiskers to feel underwater vibrations to help them to locate their food. Some of the animals they have been found to eat are: small penguins like the rockhopper penguins , short-tailed shearwaters , arrow squid , broad squid , warty squid , Antarctic flying squid , butterfish , New Zealand octopus , krill , lamprey , blind eel , ling , ahuru , crayfish, crab, lanternfish ( Myctophidae , Symbolophonts , Lampanyctodes hectoris , Gymnoscopelus , Electrona ), juvenile red cod , blue cod , flounder , whiptail , kahawai , horse mackerel , redbait , anchovy , ocean jackets , hagfish , spiny dogfish , school shark , sprat , silverside , lightfish , hoki , rattail , tarakihi , opalfish , Graham's gudgeon , barracouta , rostfish , warehou , lemon sole , sole , wary fish , dory , yelloweyed mullet , dwarf cod , Oliver's rattail , yellow weever , silver warehou , Southern blue whiting , javelin fish , deepsea smelt , common roughy , seaperch , and pilchard . Very few of these species are commercially important.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • piscivore piscivore
  • molluscivore molluscivore
  • eats other marine invertebrates

• Animal Foods
• birds
• fish
• mollusks
• aquatic crustaceans
• other marine invertebrates

Predation

Known predators include sharks, orcas , leopard seals , New Zealand sea lions , and humans . The only primary anti-predator adaptation the New Zealand fur seal has acquired through evolution is its coat color that blends into its rocky land surroundings, its ability to swim swiftly through water, and its ability to climb onto shore.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

New Zealand fur seals host bacteria such as Mycobacteria tuberculosis and Campylobacter jejuni along with a few parasites. Lungworms such as Parafilaroides normani and Otostrongylus spp. also have been found along with respiratory mites ( Orthohalaracne ). New Zealand fur seals may also have blubber-cysts, which are the larvae of the cestode, Phyllobothrium enclosed in a cyst. Hookworms ( Uncinaria spp.) and large roundworms such as Contracaecum , Psuedoterranova , Phocascaris and Anisakis are the most common parasites found in fur seals. Large amounts of these roundworms have been known to cause stomach ulcers.

Economic Importance for Humans: Positive

New Zealand fur seals were a popular source of food and clothing to the Polynesian culture. When the European sealers arrived in the 19th century, they nearly caused the extinction of fur seals. Today, New Zealand fur seals also have become a popular modern day tourist attraction. To increase the profit of tourism, the tourist operations have created swim-with-seal programs.

• Positive Impacts
• food food
• body parts are source of valuable material
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

New Zealand fur seals cause negligible economic harm to humans. They often get caught in fishery nets and squid trawls, which could cause a negative economic impact. As seal populations grow, collisions with motor vehicles are on the rise.

Conservation Status

New Zealand fur seals are listed as a low risk on the IUCN Red List, because they were once harvested by the native Polynesian culture and European sealers in the 1900s. In 1972, fur seals were given national protection. Trawling nets have been a source of drowning and entanglement to more than 10,000 New Zealand fur seals from 1989 to 1998. Hence, environmental groups are advocating for the creation of a trawl net that will not catch marine mammals. Environmentalists are also advising fish farms to build seal-proof barriers or away from fur seal habitats. Tourism also causes disturbances for the seals. They will often abandon those areas for quieter island shores. New Zealand fur seals are now protected by laws in Australia and New Zealand. All marine mammals of New Zealand are protected by the Marine Mammals Protection Act of 1978. In 2004, the Department of Conservation established a 5-year Conservation Plan. The Australian Commonwealth Government and the State Government each have their own jurisdiction over all marine animals that are within 4.8 km of the coast. New Zealand fur seals are protected by the Marine Mammal Sanctuary that was created in the Auckland Islands and by UNESCO in 1998 when they granted the New Zealand’s subantarctic islands “World Heritage” status. In 1999 a Conservation Action Plan was published for all Australian seals. On the eastern side of Macquarie Island in 2000, a 16 million hectare Marine Park was established. The Tasmanian government then encompassed all of Tasmania’s waters and 5.6 km adjoining Tasmania into the Macquarie Island Nature Reserve. These parks, reserves, laws, conservation plans and environmentalist groups successfully protect New Zealand fur seals. Since conservation efforts went into effect, seal population numbers have been on the rise.

Additional Links

Encyclopedia of Life

Contributors

Dorothy Landgren (author), Radford University, Karen Powers (editor), Radford University, Kiersten Newtoff (editor), Radford University, Melissa Whistleman (editor), Radford University, Laura Podzikowski (editor), Special Projects.

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